上一篇咱们实现了几乎所有的数据库访问代码。这一次咱们进一步实现 GraphQL 接口封装。

一、GraphqQL 模式建立

1. 基础模式：

var baseType = graphql.NewObject(graphql.ObjectConfig{
    Name: "Base",
    Fields: graphql.Fields{
        "id":         &graphql.Field{Type: graphql.ID},
        "created_at": &graphql.Field{Type: graphql.DateTime},
        "updated_at": &graphql.Field{Type: graphql.DateTime},
        "deleted_at": &graphql.Field{Type: graphql.DateTime},
    },
    Description: "baseType",
})

2. 基础维度模式：

var baseDimensionType = graphql.NewObject(graphql.ObjectConfig{
    Name: "BaseDimension",
    Fields: graphql.Fields{
        "name":     &graphql.Field{Type: graphql.String},
        "category": &graphql.Field{Type: graphql.String},
        "content":  &graphql.Field{Type: graphql.String},
        "tag":      &graphql.Field{Type: graphql.String},
    },
    Description: "baseDimensionType",
})

3. 账号模式：

var userType = graphql.NewObject(graphql.ObjectConfig{
    Name: "User",
    Fields: graphql.Fields{
        "account":                    &graphql.Field{Type: graphql.String},
        "password":                   &graphql.Field{Type: graphql.String},
        "time_account_change_latest": &graphql.Field{Type: graphql.DateTime},
        "time_login_one":             &graphql.Field{Type: graphql.DateTime},
        "time_login_second":          &graphql.Field{Type: graphql.DateTime},
        "base":                       &graphql.Field{Type: baseType},
        "dimension_readings":         &graphql.Field{Type: graphql.NewList(dimensionReadingType)},
        "dimension_writings":         &graphql.Field{Type: graphql.NewList(dimensionWritingType)},
        "dimension_photos":           &graphql.Field{Type: graphql.NewList(dimensionPhotoType)},
        "eco_comments":               &graphql.Field{Type: graphql.NewList(ecoCommentType)},
        "system_ads":                 &graphql.Field{Type: graphql.NewList(systemAdType)},
        "bind_profiles":              &graphql.Field{Type: graphql.NewList(bindProfileType)},
    },
    Description: "userType",
})

4. 维度模式（例如：阅读金句）：

var dimensionReadingType = graphql.NewObject(graphql.ObjectConfig{
    Name: "DimensionReading",
    Fields: graphql.Fields{
        "author":         &graphql.Field{Type: graphql.String},
        "location":       &graphql.Field{Type: graphql.String},
        "base_dimension": &graphql.Field{Type: baseDimensionType},
        "eco_comments":   &graphql.Field{Type: graphql.NewList(ecoCommentType)},
        "users":          &graphql.Field{Type: graphql.NewList(userType)},
    },
    Description: "dimensionReadingType",
})

5. 生态模式（例如：评论）：

var ecoCommentType = graphql.NewObject(graphql.ObjectConfig{
    Name: "EcoComment",
    Fields: graphql.Fields{
        "data":         &graphql.Field{Type: graphql.String},
        "is_published": &graphql.Field{Type: graphql.Boolean},
        "base":         &graphql.Field{Type: baseType},
    },
    Description: "ecoCommentType",
})

二、GraphQL 端点（Endpoint）建立

1. Endpoint构建，以维度为例（其他的都类似）：

var EndpointGetDimensionReading = &graphql.Field{
    Type: responseDimensionReadingType,
    Args: graphql.FieldConfigArgument{
        "from_id":       &graphql.ArgumentConfig{Type: graphql.NewNonNull(graphql.String)},
        "from_nickname": &graphql.ArgumentConfig{Type: graphql.NewNonNull(graphql.String)},
        "content": &graphql.ArgumentConfig{
            Type:        graphql.NewNonNull(graphql.String),
            Description: "query by cond",
        },
    },
    Resolve: func(p graphql.ResolveParams) (i interface{}, err error) {
        var entities []DimensionReading
        var count int64
        content, contentOk := p.Args["content"].(string)
        fromId, fromIdOk := p.Args["from_id"].(string)
        fromNickname, fromNicknameOK := p.Args["from_nickname"].(string)
        if !contentOk || !fromIdOk || !fromNicknameOK || fromId == "" || fromNickname == "" || content == "" {
            return nil, errors.New("required id,name,content")
        }
        var condGetDetails CondGetDetails
        if !contentOk {
            return nil, errors.New("参数解析失败")
        }
        err = json.Unmarshal([]byte(content), &condGetDetails)
        if err != nil {
            return nil, errors.New("参数解析失败")
        }
        result, err := GetEntities(condGetDetails)
        if err != nil {
            return nil, err
        }
        err = result.Preload(clause.Associations).Find(&entities).Count(&count).Error

        return ResponseCommon{
            Code:    200,
            Content: entities,
            Count:   count,
            Msg: Message{
                Success: "success",
            },
        }, err
    },
}

• 每个接口访问时，除了接口必要的参数数据之外，还附带上额外的用户数据（id 和 nickname），方便以后的审计
• content 是接口必要的参数数据，使用的是前面的文章中设计好的数据结构
• 博客系统的所有接口参数尽量保持一致——这是一个能简化逻辑的约定。

2. GraphQL 的 endpoint 接入到 Gin 框架内：

var queryType = graphql.NewObject(graphql.ObjectConfig{
    Name: "Query",
    Fields: graphql.Fields{
        "dimensionReading": EndpointGetDimensionReading, //获取参展项目列表
    },
})

var Schema, _ = graphql.NewSchema(graphql.SchemaConfig{
    Query: queryType,
    //Mutation: mutationType,
})

func ExecuteQuery(schema graphql.Schema, query string, variables map[string]interface{}, operationName string) *graphql.Result {
    result := graphql.Do(graphql.Params{
        Schema:         schema,
        RequestString:  query,
        VariableValues: variables,
        OperationName:  operationName,
    })
    if len(result.Errors) > 0 {
        log.Printf("errors:%s", result.Errors)
    }
    return result
}

• Gin 框架与 GraphQL 的中间连接代码

func RouterDimension(router *gin.Engine) (interface{}, error) {
    routerDimension := router.Group("/blog/x")
    {
        routerDimension.POST("/v1", func(c *gin.Context) {
            var query Query
            err := c.BindJSON(&query)
            if err != nil {
                log.Println(err)
                c.JSON(http.StatusOK, err)
                return
            }
            result := models.ExecuteQuery(models.Schema, query.Query, query.Variables, query.OperationName) // 此处连接GraphQL
            c.JSON(http.StatusOK, result)
        })
    }
    return routerDimension, nil
}

• Gin 路由相关代码实现。