草庐IT

c# - ADO EF - TPH 中派生类型之间的错误映射关联

coder 2024-05-28 原文

背景

我正在使用 .NET Framework 3.5 SP1 在 Visual Studio 2008 SP1 中使用 ADO Entity Framework 编写数据访问库。我正在尝试在两个都派生自抽象类型的实体之间创建关联。我使用 Table Per Hierarchy 表示两个实体继承层次结构(TPH) 这意味着只有两个表 - 每个实体继承层次结构一个。

注意 您可以使用 Table Per Type (TPT) 来避免这个问题，但它有它自己的缺点。参见 here和 here在继承持久性模型之间进行选择时了解更多详细信息。

这是实体模型的设计器 View 的屏幕截图:

这是数据库架构的屏幕截图:

假设

当您在 ADO Entity Framework Designer 中创建使用 Visual Studio 2008 SP1 和 .NET Framework 3.5 SP1 使用 TPH 建模的派生类型之间的关联时，您可能会收到以下消息“错误 3034:映射了具有不同键的两个实体到同一行。确保这两个映射片段不会将具有重叠键的两组实体映射到同一组行。”

基于我所拥有的read online ，为了解决这个问题，你必须像这样在外键上的关联中添加一个条件:

<Condition ColumnName="Endpoint1" IsNull="false" />

这是对 PersonPersonToPerson1 关联进行此编辑的屏幕截图:

约束

  • 每个层次结构的基类(即节点和链接)必须是抽象的。
  • 来自两个派生类型之间关联的导航属性必须可以通过链接类型(例如 PersonToPerson 和 PersonToLocation)区分。这意味着您无法在 Link 和 Node 抽象基类之间创建关联。

问题:

当我如上所述创建实体模型并按照上述假设将条件添加到 AssociationMappings 时，我在构建/验证模型时收到“错误 3023”。

Error   1   Error 3023: Problem in Mapping Fragments starting at lines 146, 153, 159, 186, 195, 204, 213: Column Link.Endpoint1 has no default value and is not nullable. A column value is required to store entity data.
An Entity with Key (PK) will not round-trip when:
((PK is NOT in 'LinkSet' EntitySet OR PK does NOT play Role 'PersonToPerson' in AssociationSet 'PersonPersonToPerson1') AND (PK is in 'LinkSet' EntitySet OR PK plays Role 'PersonToPerson' in AssociationSet 'PersonPersonToPerson1' OR PK plays Role 'PersonToPerson' in AssociationSet 'PersonPersonToPerson'))
C:\Documents and Settings\Demo\My Documents\Visual Studio 2008\Projects\GraphExample2.BusinessEntities\GraphExample2.BusinessEntities\GraphModel.edmx   147 15  GraphExample2.BusinessEntities

Entity Framework 在上述场景中遇到的问题是有两个属性被映射到相同的外键。例如，Endpoint1 的列和外键映射到 PersonToLocation 派生类型中的 Person 属性，并映射到 PersonToPerson 派生类型中的 Leader 属性。

我不明白为什么这是个问题。由于 Leader/Follower 属性仅在 PersonToPerson 派生类型中——而不是任何其他派生类型或基类型——并且 Person/Location 属性也是如此，为什么 TypeDiscriminator 字段不足以让 EF 确定哪个设置给定行属于？

在我看来，如果您正在处理 TypeDiscriminator = 1 的对象，则将 Endpoint1 放在 Leader 中，将 Endpoint2 放在 Follower 中。同样，如果您正在处理 TypeDiscriminator = 2 的对象，则将 Endpoint1 放在 Person 中，将 Endpoint2 放在 Location 中。

问题:

如何解决错误 3023 以允许这些关联发生？

或

如何在我上面描述的 ADO Entity Framework 中创建关联类型？

引用资料:

代码

SQL:

USE [GraphExample2]
GO
/****** Object:  Table [dbo].[Node]    Script Date: 02/17/2009 14:36:13 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Node](
    [NodeID] [int] NOT NULL,
    [NodeTypeDiscriminator] [int] NOT NULL,
    [Name] [varchar](255) NOT NULL,
    [Description] [varchar](1023) NULL,
 CONSTRAINT [PK_Node] PRIMARY KEY CLUSTERED 
(
    [NodeID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
/****** Object:  Table [dbo].[Link]    Script Date: 02/17/2009 14:36:12 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Link](
    [LinkID] [int] NOT NULL,
    [LinkTypeDiscriminator] [int] NOT NULL,
    [Endpoint1] [int] NOT NULL,
    [Endpoint2] [int] NOT NULL,
    [Name] [varchar](255) NULL,
    [Description] [varchar](1023) NULL,
 CONSTRAINT [PK_Link] PRIMARY KEY CLUSTERED 
(
    [LinkID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
/****** Object:  ForeignKey [FK_Link_Node_Endpoint1]    Script Date: 02/17/2009 14:36:12 ******/
ALTER TABLE [dbo].[Link]  WITH CHECK ADD  CONSTRAINT [FK_Link_Node_Endpoint1] FOREIGN KEY([Endpoint1])
REFERENCES [dbo].[Node] ([NodeID])
GO
ALTER TABLE [dbo].[Link] CHECK CONSTRAINT [FK_Link_Node_Endpoint1]
GO
/****** Object:  ForeignKey [FK_Link_Node_Endpoint2]    Script Date: 02/17/2009 14:36:12 ******/
ALTER TABLE [dbo].[Link]  WITH CHECK ADD  CONSTRAINT [FK_Link_Node_Endpoint2] FOREIGN KEY([Endpoint2])
REFERENCES [dbo].[Node] ([NodeID])
GO
ALTER TABLE [dbo].[Link] CHECK CONSTRAINT [FK_Link_Node_Endpoint2]
GO

EDMX:

<?xml version="1.0" encoding="utf-8"?>
<edmx:Edmx Version="1.0" xmlns:edmx="http://schemas.microsoft.com/ado/2007/06/edmx">
  <!-- EF Runtime content -->
  <edmx:Runtime>
    <!-- SSDL content -->
    <edmx:StorageModels>
      <Schema Namespace="GraphModel.Store" Alias="Self" Provider="System.Data.SqlClient" ProviderManifestToken="2005" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" xmlns="http://schemas.microsoft.com/ado/2006/04/edm/ssdl">
        <EntityContainer Name="GraphModelStoreContainer">
          <EntitySet Name="Link" EntityType="GraphModel.Store.Link" store:Type="Tables" Schema="dbo" />
          <EntitySet Name="Node" EntityType="GraphModel.Store.Node" store:Type="Tables" Schema="dbo" />
          <AssociationSet Name="FK_Link_Node_Endpoint1" Association="GraphModel.Store.FK_Link_Node_Endpoint1">
            <End Role="Node" EntitySet="Node" />
            <End Role="Link" EntitySet="Link" />
          </AssociationSet>
          <AssociationSet Name="FK_Link_Node_Endpoint2" Association="GraphModel.Store.FK_Link_Node_Endpoint2">
            <End Role="Node" EntitySet="Node" />
            <End Role="Link" EntitySet="Link" />
          </AssociationSet>
        </EntityContainer>
        <EntityType Name="Link">
          <Key>
            <PropertyRef Name="LinkID" />
          </Key>
          <Property Name="LinkID" Type="int" Nullable="false" />
          <Property Name="LinkTypeDiscriminator" Type="int" Nullable="false" />
          <Property Name="Endpoint1" Type="int" Nullable="false" />
          <Property Name="Endpoint2" Type="int" Nullable="false" />
          <Property Name="Name" Type="varchar" MaxLength="255" />
          <Property Name="Description" Type="varchar" MaxLength="1023" />
        </EntityType>
        <EntityType Name="Node">
          <Key>
            <PropertyRef Name="NodeID" />
          </Key>
          <Property Name="NodeID" Type="int" Nullable="false" />
          <Property Name="NodeTypeDiscriminator" Type="int" Nullable="false" />
          <Property Name="Name" Type="varchar" Nullable="false" MaxLength="255" />
          <Property Name="Description" Type="varchar" MaxLength="1023" />
        </EntityType>
        <Association Name="FK_Link_Node_Endpoint1">
          <End Role="Node" Type="GraphModel.Store.Node" Multiplicity="1" />
          <End Role="Link" Type="GraphModel.Store.Link" Multiplicity="*" />
          <ReferentialConstraint>
            <Principal Role="Node">
              <PropertyRef Name="NodeID" />
            </Principal>
            <Dependent Role="Link">
              <PropertyRef Name="Endpoint1" />
            </Dependent>
          </ReferentialConstraint>
        </Association>
        <Association Name="FK_Link_Node_Endpoint2">
          <End Role="Node" Type="GraphModel.Store.Node" Multiplicity="1" />
          <End Role="Link" Type="GraphModel.Store.Link" Multiplicity="*" />
          <ReferentialConstraint>
            <Principal Role="Node">
              <PropertyRef Name="NodeID" />
            </Principal>
            <Dependent Role="Link">
              <PropertyRef Name="Endpoint2" />
            </Dependent>
          </ReferentialConstraint>
        </Association>
      </Schema>
    </edmx:StorageModels>
    <!-- CSDL content -->
    <edmx:ConceptualModels>
      <Schema xmlns="http://schemas.microsoft.com/ado/2006/04/edm" Namespace="GraphModel" Alias="Self">
        <EntityContainer Name="GraphModelContainer" >
          <EntitySet Name="NodeSet" EntityType="GraphModel.Node" />
          <EntitySet Name="LinkSet" EntityType="GraphModel.Link" />
          <AssociationSet Name="PersonPersonToPerson" Association="GraphModel.PersonPersonToPerson">
            <End Role="Person" EntitySet="NodeSet" />
            <End Role="PersonToPerson" EntitySet="LinkSet" />
          </AssociationSet>
          <AssociationSet Name="PersonPersonToPerson1" Association="GraphModel.PersonPersonToPerson1">
            <End Role="Person" EntitySet="NodeSet" />
            <End Role="PersonToPerson" EntitySet="LinkSet" />
          </AssociationSet>
          <AssociationSet Name="Person_PersonToLocation" Association="GraphModel.Person_PersonToLocation">
            <End Role="Person" EntitySet="NodeSet" />
            <End Role="PersonToLocation" EntitySet="LinkSet" />
          </AssociationSet>
          <AssociationSet Name="Location_PersonToLocation" Association="GraphModel.Location_PersonToLocation">
            <End Role="Location" EntitySet="NodeSet" />
            <End Role="PersonToLocation" EntitySet="LinkSet" />
          </AssociationSet>
        </EntityContainer>
        <EntityType Name="Node" Abstract="true">
          <Key>
            <PropertyRef Name="NodeId" />
          </Key>
          <Property Name="NodeId" Type="Int32" Nullable="false" />
          <Property Name="Name" Type="String" Nullable="false" />
          <Property Name="Description" Type="String" Nullable="true" />
        </EntityType>
        <EntityType Name="Person" BaseType="GraphModel.Node" >
          <NavigationProperty Name="Leaders" Relationship="GraphModel.PersonPersonToPerson" FromRole="Person" ToRole="PersonToPerson" />
          <NavigationProperty Name="Followers" Relationship="GraphModel.PersonPersonToPerson1" FromRole="Person" ToRole="PersonToPerson" />
          <NavigationProperty Name="Locations" Relationship="GraphModel.Person_PersonToLocation" FromRole="Person" ToRole="PersonToLocation" />
        </EntityType>
        <EntityType Name="Location" BaseType="GraphModel.Node" >
          <NavigationProperty Name="Visitors" Relationship="GraphModel.Location_PersonToLocation" FromRole="Location" ToRole="PersonToLocation" />
        </EntityType>
        <EntityType Name="Link" Abstract="true">
          <Key>
            <PropertyRef Name="LinkId" />
          </Key>
          <Property Name="LinkId" Type="Int32" Nullable="false" />
          <Property Name="Name" Type="String" Nullable="true" />
          <Property Name="Description" Type="String" Nullable="true" />
        </EntityType>
        <EntityType Name="PersonToPerson" BaseType="GraphModel.Link" >
          <NavigationProperty Name="Leader" Relationship="GraphModel.PersonPersonToPerson" FromRole="PersonToPerson" ToRole="Person" />
          <NavigationProperty Name="Follower" Relationship="GraphModel.PersonPersonToPerson1" FromRole="PersonToPerson" ToRole="Person" />
        </EntityType>
        <EntityType Name="PersonToLocation" BaseType="GraphModel.Link" >
          <NavigationProperty Name="Person" Relationship="GraphModel.Person_PersonToLocation" FromRole="PersonToLocation" ToRole="Person" />
          <NavigationProperty Name="Location" Relationship="GraphModel.Location_PersonToLocation" FromRole="PersonToLocation" ToRole="Location" />
        </EntityType>
        <Association Name="PersonPersonToPerson">
          <End Type="GraphModel.Person" Role="Person" Multiplicity="1" />
          <End Type="GraphModel.PersonToPerson" Role="PersonToPerson" Multiplicity="*" />
        </Association>
        <Association Name="PersonPersonToPerson1">
          <End Type="GraphModel.Person" Role="Person" Multiplicity="1" />
          <End Type="GraphModel.PersonToPerson" Role="PersonToPerson" Multiplicity="*" />
        </Association>
        <Association Name="Person_PersonToLocation">
          <End Type="GraphModel.Person" Role="Person" Multiplicity="1" />
          <End Type="GraphModel.PersonToLocation" Role="PersonToLocation" Multiplicity="*" />
        </Association>
        <Association Name="Location_PersonToLocation">
          <End Type="GraphModel.Location" Role="Location" Multiplicity="1" />
          <End Type="GraphModel.PersonToLocation" Role="PersonToLocation" Multiplicity="*" />
        </Association>
      </Schema>
    </edmx:ConceptualModels>
    <!-- C-S mapping content -->
    <edmx:Mappings>
      <Mapping xmlns="urn:schemas-microsoft-com:windows:storage:mapping:CS" Space="C-S">
        <Alias Key="Model" Value="GraphModel" />
        <Alias Key="Target" Value="GraphModel.Store" />
        <EntityContainerMapping CdmEntityContainer="GraphModelContainer" StorageEntityContainer="GraphModelStoreContainer">
          <EntitySetMapping Name="LinkSet">
            <EntityTypeMapping TypeName="IsTypeOf(GraphModel.Link)">
              <MappingFragment StoreEntitySet="Link">
                <ScalarProperty Name="Description" ColumnName="Description" />
                <ScalarProperty Name="Name" ColumnName="Name" />
                <ScalarProperty Name="LinkId" ColumnName="LinkID" />
              </MappingFragment>
            </EntityTypeMapping>
            <EntityTypeMapping TypeName="IsTypeOf(GraphModel.PersonToPerson)">
              <MappingFragment StoreEntitySet="Link" >
                <ScalarProperty Name="LinkId" ColumnName="LinkID" />
                <Condition ColumnName="LinkTypeDiscriminator" Value="1" />
              </MappingFragment>
            </EntityTypeMapping>
            <EntityTypeMapping TypeName="IsTypeOf(GraphModel.PersonToLocation)">
              <MappingFragment StoreEntitySet="Link" >
                <ScalarProperty Name="LinkId" ColumnName="LinkID" />
                <Condition ColumnName="LinkTypeDiscriminator" Value="2" />
              </MappingFragment>
            </EntityTypeMapping>
          </EntitySetMapping>
          <EntitySetMapping Name="NodeSet">
            <EntityTypeMapping TypeName="IsTypeOf(GraphModel.Node)">
              <MappingFragment StoreEntitySet="Node">
                <ScalarProperty Name="Description" ColumnName="Description" />
                <ScalarProperty Name="Name" ColumnName="Name" />
                <ScalarProperty Name="NodeId" ColumnName="NodeID" />
              </MappingFragment>
            </EntityTypeMapping>
            <EntityTypeMapping TypeName="IsTypeOf(GraphModel.Person)">
              <MappingFragment StoreEntitySet="Node" >
                <ScalarProperty Name="NodeId" ColumnName="NodeID" />
                <Condition ColumnName="NodeTypeDiscriminator" Value="1" />
              </MappingFragment>
            </EntityTypeMapping>
            <EntityTypeMapping TypeName="IsTypeOf(GraphModel.Location)">
              <MappingFragment StoreEntitySet="Node" >
                <ScalarProperty Name="NodeId" ColumnName="NodeID" />
                <Condition ColumnName="NodeTypeDiscriminator" Value="2" />
              </MappingFragment>
            </EntityTypeMapping>
          </EntitySetMapping>
          <AssociationSetMapping Name="PersonPersonToPerson1" TypeName="GraphModel.PersonPersonToPerson1" StoreEntitySet="Link">
            <EndProperty Name="Person">
              <ScalarProperty Name="NodeId" ColumnName="Endpoint1" />
            </EndProperty>
            <EndProperty Name="PersonToPerson">
              <ScalarProperty Name="LinkId" ColumnName="LinkID" />
            </EndProperty>
            <Condition ColumnName="Endpoint1" IsNull="false" />
          </AssociationSetMapping>
          <AssociationSetMapping Name="PersonPersonToPerson" TypeName="GraphModel.PersonPersonToPerson" StoreEntitySet="Link">
            <EndProperty Name="Person">
              <ScalarProperty Name="NodeId" ColumnName="Endpoint2" />
            </EndProperty>
            <EndProperty Name="PersonToPerson">
              <ScalarProperty Name="LinkId" ColumnName="LinkID" />
            </EndProperty>
            <Condition ColumnName="Endpoint2" IsNull="false" />
          </AssociationSetMapping>
          <AssociationSetMapping Name="Person_PersonToLocation" TypeName="GraphModel.Person_PersonToLocation" StoreEntitySet="Link">
            <EndProperty Name="Person">
              <ScalarProperty Name="NodeId" ColumnName="Endpoint1" />
            </EndProperty>
            <EndProperty Name="PersonToLocation">
              <ScalarProperty Name="LinkId" ColumnName="LinkID" />
            </EndProperty>
            <Condition ColumnName="Endpoint1" IsNull="false" />
          </AssociationSetMapping>
          <AssociationSetMapping Name="Location_PersonToLocation" TypeName="GraphModel.Location_PersonToLocation" StoreEntitySet="Link">
            <EndProperty Name="Location">
              <ScalarProperty Name="NodeId" ColumnName="Endpoint2" />
            </EndProperty>
            <EndProperty Name="PersonToLocation">
              <ScalarProperty Name="LinkId" ColumnName="LinkID" />
            </EndProperty>
            <Condition ColumnName="Endpoint2" IsNull="false" />
          </AssociationSetMapping>
        </EntityContainerMapping>
      </Mapping>
    </edmx:Mappings>
  </edmx:Runtime>
  <!-- EF Designer content (DO NOT EDIT MANUALLY BELOW HERE) -->
  <edmx:Designer xmlns="http://schemas.microsoft.com/ado/2007/06/edmx">
    <edmx:Connection>
      <DesignerInfoPropertySet>
        <DesignerProperty Name="MetadataArtifactProcessing" Value="EmbedInOutputAssembly" />
      </DesignerInfoPropertySet>
    </edmx:Connection>
    <edmx:Options>
      <DesignerInfoPropertySet>
        <DesignerProperty Name="ValidateOnBuild" Value="true" />
      </DesignerInfoPropertySet>
    </edmx:Options>
    <!-- Diagram content (shape and connector positions) -->
    <edmx:Diagrams>
      <Diagram Name="GraphModel" ZoomLevel="114" >
        <EntityTypeShape EntityType="GraphModel.Node" Width="1.5" PointX="5.875" PointY="1.375" Height="1.427958984375" />
        <EntityTypeShape EntityType="GraphModel.Person" Width="1.5" PointX="5.875" PointY="3.25" Height="1.4279589843749996" />
        <EntityTypeShape EntityType="GraphModel.Location" Width="1.5" PointX="7.75" PointY="4.625" Height="1.0992643229166665" />
        <InheritanceConnector EntityType="GraphModel.Location">
          <ConnectorPoint PointX="7.375" PointY="2.0889794921875" />
          <ConnectorPoint PointX="8.5" PointY="2.0889794921875" />
          <ConnectorPoint PointX="8.5" PointY="4.625" />
        </InheritanceConnector>
        <EntityTypeShape EntityType="GraphModel.Link" Width="1.5" PointX="2.875" PointY="1.375" Height="1.427958984375" />
        <EntityTypeShape EntityType="GraphModel.PersonToPerson" Width="1.75" PointX="2.625" PointY="3.125" Height="0.9349169921875" />
        <InheritanceConnector EntityType="GraphModel.PersonToPerson">
          <ConnectorPoint PointX="3.625" PointY="2.802958984375" />
          <ConnectorPoint PointX="3.625" PointY="3.125" />
        </InheritanceConnector>
        <InheritanceConnector EntityType="GraphModel.Person">
          <ConnectorPoint PointX="6.625" PointY="2.802958984375" />
          <ConnectorPoint PointX="6.625" PointY="3.25" />
        </InheritanceConnector>
        <EntityTypeShape EntityType="GraphModel.PersonToLocation" Width="1.875" PointX="0.75" PointY="4.625" Height="1.2636116536458326" />
        <InheritanceConnector EntityType="GraphModel.PersonToLocation">
          <ConnectorPoint PointX="2.875" PointY="2.0889794921875" />
          <ConnectorPoint PointX="1.65625" PointY="2.0889794921875" />
          <ConnectorPoint PointX="1.65625" PointY="4.625" />
        </InheritanceConnector>
        <AssociationConnector Association="GraphModel.PersonPersonToPerson">
          <ConnectorPoint PointX="5.875" PointY="3.8193058268229163" />
          <ConnectorPoint PointX="4.375" PointY="3.8193058268229163" />
        </AssociationConnector>
        <AssociationConnector Association="GraphModel.PersonPersonToPerson1">
          <ConnectorPoint PointX="5.875" PointY="3.4721529134114579" />
          <ConnectorPoint PointX="4.375" PointY="3.4721529134114579" />
        </AssociationConnector>
        <AssociationConnector Association="GraphModel.Person_PersonToLocation">
          <ConnectorPoint PointX="6.625" PointY="4.677958984375" />
          <ConnectorPoint PointX="6.625" PointY="5.1875" />
          <ConnectorPoint PointX="2.625" PointY="5.1875" />
        </AssociationConnector>
        <AssociationConnector Association="GraphModel.Location_PersonToLocation">
          <ConnectorPoint PointX="7.75" PointY="5.4791666666666661" />
          <ConnectorPoint PointX="2.625" PointY="5.4791666666666661" />
        </AssociationConnector>
      </Diagram>
    </edmx:Diagrams>
  </edmx:Designer>
</edmx:Edmx>

最佳答案

可能的解决方法

  1. 为派生类型之间的每个关联创建一个单独的列，并使每个列都可为空
  2. 在每个新列和主键表之间创建一个外键。
  3. 将实体模型中的每个关联映射到特定的唯一列和外键，以便每个列和外键仅使用一次。

问题

这是一个非常不受欢迎的解决方案，因为它激增了您需要的列数。

  • 更多列 - 为派生类型之间的每个关联添加一列会导致列数激增。
  • 空列 对于 TPH，这意味着您的表中将有很多空列。
  • SQL JOIN - 从 TPH 切换到 TPT 以避免空列的数量导致 EF 必须非常频繁地使用 JOIN(几乎每次您处理任何派生类型)。
  • 重构 如果您将来添加派生类型，您不仅需要更新实体模型 (*.edmx) 及其映射，还必须通过以下方式更改数据库架构添加额外的列!

例子

对于上面的链接/节点示例，生成的数据库架构如下所示:

代码

SQL:

USE [GraphExample2]
GO
/****** Object:  Table [dbo].[Node]    Script Date: 02/26/2009 15:45:53 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Node](
    [NodeID] [int] IDENTITY(1,1) NOT NULL,
    [NodeTypeDiscriminator] [int] NOT NULL,
    [Name] [varchar](255) NOT NULL,
    [Description] [varchar](1023) NULL,
 CONSTRAINT [PK_Node] PRIMARY KEY CLUSTERED 
(
    [NodeID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
/****** Object:  Table [dbo].[Link]    Script Date: 02/26/2009 15:45:53 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Link](
    [LinkID] [int] IDENTITY(1,1) NOT NULL,
    [LinkTypeDiscriminator] [int] NOT NULL,
    [LeaderID] [int] NULL,
    [FollowerID] [int] NULL,
    [PersonID] [int] NULL,
    [LocationID] [int] NULL,
    [Name] [varchar](255) NULL,
    [Description] [varchar](1023) NULL,
 CONSTRAINT [PK_Link] PRIMARY KEY CLUSTERED 
(
    [LinkID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
/****** Object:  ForeignKey [FK_Link_Node_Follower]    Script Date: 02/26/2009 15:45:53 ******/
ALTER TABLE [dbo].[Link]  WITH CHECK ADD  CONSTRAINT [FK_Link_Node_Follower] FOREIGN KEY([FollowerID])
REFERENCES [dbo].[Node] ([NodeID])
GO
ALTER TABLE [dbo].[Link] CHECK CONSTRAINT [FK_Link_Node_Follower]
GO
/****** Object:  ForeignKey [FK_Link_Node_Leader]    Script Date: 02/26/2009 15:45:53 ******/
ALTER TABLE [dbo].[Link]  WITH CHECK ADD  CONSTRAINT [FK_Link_Node_Leader] FOREIGN KEY([LeaderID])
REFERENCES [dbo].[Node] ([NodeID])
GO
ALTER TABLE [dbo].[Link] CHECK CONSTRAINT [FK_Link_Node_Leader]
GO
/****** Object:  ForeignKey [FK_Link_Node_Location]    Script Date: 02/26/2009 15:45:53 ******/
ALTER TABLE [dbo].[Link]  WITH CHECK ADD  CONSTRAINT [FK_Link_Node_Location] FOREIGN KEY([LocationID])
REFERENCES [dbo].[Node] ([NodeID])
GO
ALTER TABLE [dbo].[Link] CHECK CONSTRAINT [FK_Link_Node_Location]
GO
/****** Object:  ForeignKey [FK_Link_Node_Person]    Script Date: 02/26/2009 15:45:53 ******/
ALTER TABLE [dbo].[Link]  WITH CHECK ADD  CONSTRAINT [FK_Link_Node_Person] FOREIGN KEY([PersonID])
REFERENCES [dbo].[Node] ([NodeID])
GO
ALTER TABLE [dbo].[Link] CHECK CONSTRAINT [FK_Link_Node_Person]
GO

EDMX:

<?xml version="1.0" encoding="utf-8"?>
  <edmx:Edmx Version="1.0" xmlns:edmx="http://schemas.microsoft.com/ado/2007/06/edmx">
    <!-- EF Runtime content -->
    <edmx:Runtime>
      <!-- SSDL content -->
      <edmx:StorageModels>
        <Schema Namespace="GraphModel.Store" Alias="Self" Provider="System.Data.SqlClient" ProviderManifestToken="2005" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" xmlns="http://schemas.microsoft.com/ado/2006/04/edm/ssdl">
          <EntityContainer Name="GraphModelStoreContainer">
            <EntitySet Name="Link" EntityType="GraphModel.Store.Link" store:Type="Tables" Schema="dbo" />
            <EntitySet Name="Node" EntityType="GraphModel.Store.Node" store:Type="Tables" Schema="dbo" />
            <AssociationSet Name="FK_Link_Node_Follower" Association="GraphModel.Store.FK_Link_Node_Follower">
              <End Role="Node" EntitySet="Node" />
              <End Role="Link" EntitySet="Link" />
            </AssociationSet>
            <AssociationSet Name="FK_Link_Node_Leader" Association="GraphModel.Store.FK_Link_Node_Leader">
              <End Role="Node" EntitySet="Node" />
              <End Role="Link" EntitySet="Link" />
            </AssociationSet>
            <AssociationSet Name="FK_Link_Node_Location" Association="GraphModel.Store.FK_Link_Node_Location">
              <End Role="Node" EntitySet="Node" />
              <End Role="Link" EntitySet="Link" />
            </AssociationSet>
            <AssociationSet Name="FK_Link_Node_Person" Association="GraphModel.Store.FK_Link_Node_Person">
              <End Role="Node" EntitySet="Node" />
              <End Role="Link" EntitySet="Link" />
            </AssociationSet>
          </EntityContainer>
          <EntityType Name="Link">
            <Key>
              <PropertyRef Name="LinkID" />
            </Key>
            <Property Name="LinkID" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
            <Property Name="LinkTypeDiscriminator" Type="int" Nullable="false" />
            <Property Name="LeaderID" Type="int" />
            <Property Name="FollowerID" Type="int" />
            <Property Name="PersonID" Type="int" />
            <Property Name="LocationID" Type="int" />
            <Property Name="Name" Type="varchar" MaxLength="255" />
            <Property Name="Description" Type="varchar" MaxLength="1023" />
          </EntityType>
          <EntityType Name="Node">
            <Key>
              <PropertyRef Name="NodeID" />
            </Key>
            <Property Name="NodeID" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
            <Property Name="NodeTypeDiscriminator" Type="int" Nullable="false" />
            <Property Name="Name" Type="varchar" Nullable="false" MaxLength="255" />
            <Property Name="Description" Type="varchar" MaxLength="1023" />
          </EntityType>
          <Association Name="FK_Link_Node_Follower">
            <End Role="Node" Type="GraphModel.Store.Node" Multiplicity="0..1" />
            <End Role="Link" Type="GraphModel.Store.Link" Multiplicity="*" />
            <ReferentialConstraint>
              <Principal Role="Node">
                <PropertyRef Name="NodeID" />
              </Principal>
              <Dependent Role="Link">
                <PropertyRef Name="FollowerID" />
              </Dependent>
            </ReferentialConstraint>
          </Association>
          <Association Name="FK_Link_Node_Leader">
            <End Role="Node" Type="GraphModel.Store.Node" Multiplicity="0..1" />
            <End Role="Link" Type="GraphModel.Store.Link" Multiplicity="*" />
            <ReferentialConstraint>
              <Principal Role="Node">
                <PropertyRef Name="NodeID" />
              </Principal>
              <Dependent Role="Link">
                <PropertyRef Name="LeaderID" />
              </Dependent>
            </ReferentialConstraint>
          </Association>
          <Association Name="FK_Link_Node_Location">
            <End Role="Node" Type="GraphModel.Store.Node" Multiplicity="0..1" />
            <End Role="Link" Type="GraphModel.Store.Link" Multiplicity="*" />
            <ReferentialConstraint>
              <Principal Role="Node">
                <PropertyRef Name="NodeID" />
              </Principal>
              <Dependent Role="Link">
                <PropertyRef Name="LocationID" />
              </Dependent>
            </ReferentialConstraint>
          </Association>
          <Association Name="FK_Link_Node_Person">
            <End Role="Node" Type="GraphModel.Store.Node" Multiplicity="0..1" />
            <End Role="Link" Type="GraphModel.Store.Link" Multiplicity="*" />
            <ReferentialConstraint>
              <Principal Role="Node">
                <PropertyRef Name="NodeID" />
              </Principal>
              <Dependent Role="Link">
                <PropertyRef Name="PersonID" />
              </Dependent>
            </ReferentialConstraint>
          </Association>
        </Schema>
      </edmx:StorageModels>
      <!-- CSDL content -->
      <edmx:ConceptualModels>
        <Schema xmlns="http://schemas.microsoft.com/ado/2006/04/edm" Namespace="GraphModel" Alias="Self">
          <EntityContainer Name="GraphModelContainer" >
            <EntitySet Name="NodeSet" EntityType="GraphModel.Node" />
            <EntitySet Name="LinkSet" EntityType="GraphModel.Link" />
            <AssociationSet Name="PersonPersonToPerson_Leader" Association="GraphModel.PersonPersonToPerson_Leader">
              <End Role="Person" EntitySet="NodeSet" />
              <End Role="PersonToPerson" EntitySet="LinkSet" />
            </AssociationSet>
            <AssociationSet Name="PersonPersonToPerson_Follower" Association="GraphModel.PersonPersonToPerson_Follower">
              <End Role="Person" EntitySet="NodeSet" />
              <End Role="PersonToPerson" EntitySet="LinkSet" />
            </AssociationSet>
            <AssociationSet Name="Person_PersonToLocation" Association="GraphModel.Person_PersonToLocation">
              <End Role="Person" EntitySet="NodeSet" />
              <End Role="PersonToLocation" EntitySet="LinkSet" />
            </AssociationSet>
            <AssociationSet Name="Location_PersonToLocation" Association="GraphModel.Location_PersonToLocation">
              <End Role="Location" EntitySet="NodeSet" />
              <End Role="PersonToLocation" EntitySet="LinkSet" />
            </AssociationSet>
          </EntityContainer>
          <EntityType Name="Node" Abstract="true">
            <Key>
              <PropertyRef Name="NodeId" />
            </Key>
            <Property Name="NodeId" Type="Int32" Nullable="false" />
            <Property Name="Name" Type="String" Nullable="false" />
            <Property Name="Description" Type="String" Nullable="true" />
          </EntityType>
          <EntityType Name="Person" BaseType="GraphModel.Node" >
            <NavigationProperty Name="Leaders" Relationship="GraphModel.PersonPersonToPerson_Leader" FromRole="Person" ToRole="PersonToPerson" />
            <NavigationProperty Name="Followers" Relationship="GraphModel.PersonPersonToPerson_Follower" FromRole="Person" ToRole="PersonToPerson" />
            <NavigationProperty Name="Locations" Relationship="GraphModel.Person_PersonToLocation" FromRole="Person" ToRole="PersonToLocation" />
          </EntityType>
          <EntityType Name="Location" BaseType="GraphModel.Node" >
            <NavigationProperty Name="Visitors" Relationship="GraphModel.Location_PersonToLocation" FromRole="Location" ToRole="PersonToLocation" />
          </EntityType>
          <EntityType Name="Link" Abstract="true">
            <Key>
              <PropertyRef Name="LinkId" />
            </Key>
            <Property Name="LinkId" Type="Int32" Nullable="false" />
            <Property Name="Name" Type="String" Nullable="true" />
            <Property Name="Description" Type="String" Nullable="true" />
          </EntityType>
          <EntityType Name="PersonToPerson" BaseType="GraphModel.Link" >
            <NavigationProperty Name="Leader" Relationship="GraphModel.PersonPersonToPerson_Leader" FromRole="PersonToPerson" ToRole="Person" />
            <NavigationProperty Name="Follower" Relationship="GraphModel.PersonPersonToPerson_Follower" FromRole="PersonToPerson" ToRole="Person" />
          </EntityType>
          <EntityType Name="PersonToLocation" BaseType="GraphModel.Link" >
            <NavigationProperty Name="Person" Relationship="GraphModel.Person_PersonToLocation" FromRole="PersonToLocation" ToRole="Person" />
            <NavigationProperty Name="Location" Relationship="GraphModel.Location_PersonToLocation" FromRole="PersonToLocation" ToRole="Location" />
          </EntityType>
          <Association Name="PersonPersonToPerson_Leader">
            <End Type="GraphModel.Person" Role="Person" Multiplicity="1" />
            <End Type="GraphModel.PersonToPerson" Role="PersonToPerson" Multiplicity="*" />
          </Association>
          <Association Name="PersonPersonToPerson_Follower">
            <End Type="GraphModel.Person" Role="Person" Multiplicity="1" />
            <End Type="GraphModel.PersonToPerson" Role="PersonToPerson" Multiplicity="*" />
          </Association>
          <Association Name="Person_PersonToLocation">
            <End Type="GraphModel.Person" Role="Person" Multiplicity="1" />
            <End Type="GraphModel.PersonToLocation" Role="PersonToLocation" Multiplicity="*" />
          </Association>
          <Association Name="Location_PersonToLocation">
            <End Type="GraphModel.Location" Role="Location" Multiplicity="1" />
            <End Type="GraphModel.PersonToLocation" Role="PersonToLocation" Multiplicity="*" />
          </Association>
        </Schema>
      </edmx:ConceptualModels>
      <!-- C-S mapping content -->
      <edmx:Mappings>
        <Mapping xmlns="urn:schemas-microsoft-com:windows:storage:mapping:CS" Space="C-S">
          <Alias Key="Model" Value="GraphModel" />
          <Alias Key="Target" Value="GraphModel.Store" />
          <EntityContainerMapping CdmEntityContainer="GraphModelContainer" StorageEntityContainer="GraphModelStoreContainer">
            <EntitySetMapping Name="LinkSet">
              <EntityTypeMapping TypeName="IsTypeOf(GraphModel.Link)">
                <MappingFragment StoreEntitySet="Link">
                  <ScalarProperty Name="Description" ColumnName="Description" />
                  <ScalarProperty Name="Name" ColumnName="Name" />
                  <ScalarProperty Name="LinkId" ColumnName="LinkID" />
                </MappingFragment>
              </EntityTypeMapping>
              <EntityTypeMapping TypeName="IsTypeOf(GraphModel.PersonToPerson)">
                <MappingFragment StoreEntitySet="Link" >
                  <ScalarProperty Name="LinkId" ColumnName="LinkID" />
                  <Condition ColumnName="LinkTypeDiscriminator" Value="1" />
                </MappingFragment>
              </EntityTypeMapping>
              <EntityTypeMapping TypeName="IsTypeOf(GraphModel.PersonToLocation)">
                <MappingFragment StoreEntitySet="Link" >
                  <ScalarProperty Name="LinkId" ColumnName="LinkID" />
                  <Condition ColumnName="LinkTypeDiscriminator" Value="2" />
                </MappingFragment>
              </EntityTypeMapping>
            </EntitySetMapping>
            <EntitySetMapping Name="NodeSet">
              <EntityTypeMapping TypeName="IsTypeOf(GraphModel.Node)">
                <MappingFragment StoreEntitySet="Node">
                  <ScalarProperty Name="Description" ColumnName="Description" />
                  <ScalarProperty Name="Name" ColumnName="Name" />
                  <ScalarProperty Name="NodeId" ColumnName="NodeID" />
                </MappingFragment>
              </EntityTypeMapping>
              <EntityTypeMapping TypeName="IsTypeOf(GraphModel.Person)">
                <MappingFragment StoreEntitySet="Node" >
                  <ScalarProperty Name="NodeId" ColumnName="NodeID" />
                  <Condition ColumnName="NodeTypeDiscriminator" Value="1" />
                </MappingFragment>
              </EntityTypeMapping>
              <EntityTypeMapping TypeName="IsTypeOf(GraphModel.Location)">
                <MappingFragment StoreEntitySet="Node" >
                  <ScalarProperty Name="NodeId" ColumnName="NodeID" />
                  <Condition ColumnName="NodeTypeDiscriminator" Value="2" />
                </MappingFragment>
              </EntityTypeMapping>
            </EntitySetMapping>
            <AssociationSetMapping Name="PersonPersonToPerson_Follower" TypeName="GraphModel.PersonPersonToPerson_Follower" StoreEntitySet="Link">
              <EndProperty Name="Person">
                <ScalarProperty Name="NodeId" ColumnName="FollowerID" />
              </EndProperty>
              <EndProperty Name="PersonToPerson">
                <ScalarProperty Name="LinkId" ColumnName="LinkID" />
              </EndProperty>
            </AssociationSetMapping>
            <AssociationSetMapping Name="PersonPersonToPerson_Leader" TypeName="GraphModel.PersonPersonToPerson_Leader" StoreEntitySet="Link">
              <EndProperty Name="Person">
                <ScalarProperty Name="NodeId" ColumnName="LeaderID" />
              </EndProperty>
              <EndProperty Name="PersonToPerson">
                <ScalarProperty Name="LinkId" ColumnName="LinkID" />
              </EndProperty>
            </AssociationSetMapping>
            <AssociationSetMapping Name="Person_PersonToLocation" TypeName="GraphModel.Person_PersonToLocation" StoreEntitySet="Link">
              <EndProperty Name="Person">
                <ScalarProperty Name="NodeId" ColumnName="PersonID" />
              </EndProperty>
              <EndProperty Name="PersonToLocation">
                <ScalarProperty Name="LinkId" ColumnName="LinkID" />
              </EndProperty>
            </AssociationSetMapping>
            <AssociationSetMapping Name="Location_PersonToLocation" TypeName="GraphModel.Location_PersonToLocation" StoreEntitySet="Link">
              <EndProperty Name="Location">
                <ScalarProperty Name="NodeId" ColumnName="LocationID" />
              </EndProperty>
              <EndProperty Name="PersonToLocation">
                <ScalarProperty Name="LinkId" ColumnName="LinkID" />
              </EndProperty>
            </AssociationSetMapping>
          </EntityContainerMapping>
        </Mapping>
      </edmx:Mappings>
    </edmx:Runtime>
    <!-- EF Designer content (DO NOT EDIT MANUALLY BELOW HERE) -->
    <edmx:Designer xmlns="http://schemas.microsoft.com/ado/2007/06/edmx">
      <edmx:Connection>
        <DesignerInfoPropertySet>
          <DesignerProperty Name="MetadataArtifactProcessing" Value="EmbedInOutputAssembly" />
        </DesignerInfoPropertySet>
      </edmx:Connection>
      <edmx:Options>
        <DesignerInfoPropertySet>
          <DesignerProperty Name="ValidateOnBuild" Value="true" />
        </DesignerInfoPropertySet>
      </edmx:Options>
      <!-- Diagram content (shape and connector positions) -->
      <edmx:Diagrams>
        <Diagram Name="GraphModel" ZoomLevel="114" >
          <EntityTypeShape EntityType="GraphModel.Node" Width="1.5" PointX="5.875" PointY="1.375" Height="1.427958984375" />
          <EntityTypeShape EntityType="GraphModel.Person" Width="1.5" PointX="5.875" PointY="3.25" Height="1.4279589843749996" />
          <EntityTypeShape EntityType="GraphModel.Location" Width="1.5" PointX="7.75" PointY="4.625" Height="1.0992643229166665" />
          <InheritanceConnector EntityType="GraphModel.Location">
            <ConnectorPoint PointX="7.375" PointY="2.4176741536458342" />
            <ConnectorPoint PointX="8.5" PointY="2.4176741536458342" />
            <ConnectorPoint PointX="8.5" PointY="4.625" />
          </InheritanceConnector>
          <EntityTypeShape EntityType="GraphModel.Link" Width="1.5" PointX="2.875" PointY="1.375" Height="1.427958984375" />
          <EntityTypeShape EntityType="GraphModel.PersonToPerson" Width="1.75" PointX="2.75" PointY="3.25" Height="1.2636116536458326" />
          <InheritanceConnector EntityType="GraphModel.PersonToPerson" ManuallyRouted="false">
            <ConnectorPoint PointX="3.625" PointY="2.802958984375" />
            <ConnectorPoint PointX="3.625" PointY="3.25" />
          </InheritanceConnector>
          <InheritanceConnector EntityType="GraphModel.Person">
            <ConnectorPoint PointX="6.625" PointY="3.4603483072916683" />
            <ConnectorPoint PointX="6.625" PointY="3.25" />
          </InheritanceConnector>
          <EntityTypeShape EntityType="GraphModel.PersonToLocation" Width="1.875" PointX="0.75" PointY="4.625" Height="1.2636116536458326" />
          <InheritanceConnector EntityType="GraphModel.PersonToLocation">
            <ConnectorPoint PointX="2.875" PointY="2.4176741536458342" />
            <ConnectorPoint PointX="1.65625" PointY="2.4176741536458342" />
            <ConnectorPoint PointX="1.65625" PointY="4.625" />
          </InheritanceConnector>
          <AssociationConnector Association="GraphModel.PersonPersonToPerson_Leader">
            <ConnectorPoint PointX="5.875" PointY="3.8818058268229163" />
            <ConnectorPoint PointX="4.5" PointY="3.8818058268229163" />
          </AssociationConnector>
          <AssociationConnector Association="GraphModel.PersonPersonToPerson_Follower">
            <ConnectorPoint PointX="5.875" PointY="3.5034029134114579" />
            <ConnectorPoint PointX="4.5" PointY="3.5034029134114579" />
          </AssociationConnector>
          <AssociationConnector Association="GraphModel.Person_PersonToLocation">
            <ConnectorPoint PointX="6.625" PointY="4.677958984375" />
            <ConnectorPoint PointX="6.625" PointY="5.0078214863281243" />
            <ConnectorPoint PointX="2.625" PointY="5.0078214863281243" />
          </AssociationConnector>
          <AssociationConnector Association="GraphModel.Location_PersonToLocation">
            <ConnectorPoint PointX="7.75" PointY="5.40018798828125" />
            <ConnectorPoint PointX="2.625" PointY="5.40018798828125" />
          </AssociationConnector>
        </Diagram>
      </edmx:Diagrams>
    </edmx:Designer>
  </edmx:Edmx>

关于c# - ADO EF - TPH 中派生类型之间的错误映射关联，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/558462/

中派c#34gtltentity-frameworkorm

有关c# - ADO EF - TPH 中派生类型之间的错误映射关联的更多相关文章

  1. ruby-on-rails - Rails 常用字符串(用于通知和错误信息等) - 2

    大约一年前，我决定确保每个包含非唯一文本的Flash通知都将从模块中的方法中获取文本。我这样做的最初原因是为了避免一遍又一遍地输入相同的字符串。如果我想更改措辞，我可以在一个地方轻松完成，而且一遍又一遍地重复同一件事而出现拼写错误的可能性也会降低。我最终得到的是这样的:moduleMessagesdefformat_error_messages(errors)errors.map{|attribute,message|"Error:#{attribute.to_s.titleize}#{message}."}enddeferror_message_could_not_find(obje

  2. ruby-on-rails - Rails 应用程序之间的通信 - 2

    我构建了两个需要相互通信和发送文件的Rails应用程序。例如，一个Rails应用程序会发送请求以查看其他应用程序数据库中的表。然后另一个应用程序将呈现该表的json并将其发回。我还希望一个应用程序将存储在其公共(public)目录中的文本文件发送到另一个应用程序的公共(public)目录。我从来没有做过这样的事情，所以我什至不知道从哪里开始。任何帮助，将不胜感激。谢谢! 最佳答案 无论Rails是什么，几乎所有Web应用程序都有您的要求，大多数现代Web应用程序都需要相互通信。但是有一个小小的理解需要你坚持下去，网站不应直接访问彼此

  3. ruby - 续集在添加关联时访问many_to_many连接表 - 2

    我正在使用Sequel构建一个愿望list系统。我有一个wishlists和itemstable和一个items_wishlists连接表(该名称是续集选择的名称)。items_wishlists表还有一个用于facebookid的额外列(因此我可以存储opengraph操作)，这是一个NOTNULL列。我还有Wishlist和Item具有续集many_to_many关联的模型已建立。Wishlist类也有:selectmany_to_many关联的选项设置为select:[:items.*,:items_wishlists__facebook_action_id].有没有一种方法可以

  4. ruby - Infinity 和 NaN 的类型是什么？ - 2

    我可以得到Infinity和NaNn=9.0/0#=>Infinityn.class#=>Floatm=0/0.0#=>NaNm.class#=>Float但是当我想直接访问Infinity或NaN时:Infinity#=>uninitializedconstantInfinity(NameError)NaN#=>uninitializedconstantNaN(NameError)什么是Infinity和NaN？它们是对象、关键字还是其他东西？ 最佳答案 您看到打印为Infinity和NaN的只是Float类的两个特殊实例的字符串

  5. ruby - 检查方法参数的类型 - 2

    我不确定传递给方法的对象的类型是否正确。我可能会将一个字符串传递给一个只能处理整数的函数。某种运行时保证怎么样？我看不到比以下更好的选择:defsomeFixNumMangler(input)raise"wrongtype:integerrequired"unlessinput.class==FixNumother_stuffend有更好的选择吗？ 最佳答案 使用Kernel#Integer在使用之前转换输入的方法。当无法以任何合理的方式将输入转换为整数时，它将引发ArgumentError。defmy_method(number)

  6. ruby-on-rails - 迷你测试错误 : "NameError: uninitialized constant" - 2

    我遵循MichaelHartl的“RubyonRails教程:学习Web开发”，并创建了检查用户名和电子邮件长度有效性的测试(名称最多50个字符，电子邮件最多255个字符)。test/helpers/application_helper_test.rb的内容是:require'test_helper'classApplicationHelperTest在运行bundleexecraketest时，所有测试都通过了，但我看到以下消息在最后被标记为错误:ERROR["test_full_title_helper",ApplicationHelperTest,1.820016791]test

  7. ruby-on-rails - 如何在 Rails View 上显示错误消息？ - 2

    我是rails的新手，想在form字段上应用验证。myviewsnew.html.erb.....模拟.rbclassSimulation{:in=>1..25,:message=>'Therowmustbebetween1and25'}end模拟Controller.rbclassSimulationsController我想检查模型类中row字段的整数范围，如果不在范围内则返回错误信息。我可以检查上面代码的范围，但无法返回错误消息提前致谢 最佳答案 关键是您使用的是模型表单，一种显示ActiveRecord模型实例属性的表单。c

  8. 使用 ACL 调用 upload_file 时出现 Ruby S3 "Access Denied"错误 - 2

    我正在尝试编写一个将文件上传到AWS并公开该文件的Ruby脚本。我做了以下事情:s3=Aws::S3::Resource.new(credentials:Aws::Credentials.new(KEY,SECRET),region:'us-west-2')obj=s3.bucket('stg-db').object('key')obj.upload_file(filename)这似乎工作正常，除了该文件不是公开可用的，而且我无法获得它的公共(public)URL。但是当我登录到S3时，我可以正常查看我的文件。为了使其公开可用，我将最后一行更改为obj.upload_file(file

  9. ruby-on-rails - 错误 : Error installing pg: ERROR: Failed to build gem native extension - 2

    我克隆了一个rails仓库，我现在正尝试捆绑安装背景:OSXElCapitanruby2.2.3p173(2015-08-18修订版51636)[x86_64-darwin15]rails-v在您的Gemfile中列出的或native可用的任何gem源中找不到gem'pg(>=0)ruby​​'。运行bundleinstall以安装缺少的gem。bundleinstallFetchinggemmetadatafromhttps://rubygems.org/............Fetchingversionmetadatafromhttps://rubygems.org/...Fe

  10. ruby - ＃之间？ Cooper 的 *Beginning Ruby* 中的错误或异常 - 2

    在Cooper的书BeginningRuby中，第166页有一个我无法重现的示例。classSongincludeComparableattr_accessor:lengthdef(other)@lengthother.lengthenddefinitialize(song_name,length)@song_name=song_name@length=lengthendenda=Song.new('Rockaroundtheclock',143)b=Song.new('BohemianRhapsody',544)c=Song.new('MinuteWaltz',60)a.betwee

随机推荐