我在 mongo 中有这样的数据:

"trd" : ISODate("2003-12-08T00:00:00Z")

现在，我正在像这样从 Mongo 获取数据作为 BsonDocument:

 var builder = Builders<BsonDocument>.Filter;
            var filter = builder.Eq("wsid", id);
            var mongoListBatch = _client.GetManyByFilter(filter, "directory");
            JsonWriterSettings settings = new JsonWriterSettings();
            settings.OutputMode = JsonOutputMode.Strict;

            var lists = mongoListBatch.ToJson(settings);

问题是我希望在 json 中得到像这样的 DateTime 对象:

 "transactiedatum": "23-02-1993"

但是，我得到:

 "transactiedatum": {
          "$date": 1070841600000
        }

首先，它的unix时间格式，其次，json结构有变化。我该如何处理？

最佳答案

我们遇到了类似的问题。这听起来很复杂，但没什么大不了的。

所以，首先，这是 github 上 Mongo C# 驱动器的链接: MongoC#Driver

对你来说，这里有两个重要的链接:

1. Bson Extension Methods
2. JsonWriter
3. JsonWriterContext

我们想要实现的是我们不希望 Json 字符串中的表示是 unix 时间戳格式，所以我们将这些类以不同的名称复制到我们的项目中，所以，这里是所有的类:

扩展类:

using System;
using System.IO;
using MongoDB.Bson.IO;
using MongoDB.Bson.Serialization;
using MongoDB.Bson;

    namespace Fishing.MongoDB.Serializers
    {
        public static class MyJsonWriterSettings
        {

            /// <summary>
            /// Serializes an object to a BSON byte array.
            /// </summary>
            /// <typeparam name="TNominalType">The nominal type of the object.</typeparam>
            /// <param name="obj">The object.</param>
            /// <param name="serializer">The serializer.</param>
            /// <param name="writerSettings">The writer settings.</param>
            /// <param name="configurator">The serialization context configurator.</param>
            /// <param name="args">The serialization args.</param>
            /// <returns>A BSON byte array.</returns>
            public static byte[] ToBson<TNominalType>(
                this TNominalType obj,
                IBsonSerializer<TNominalType> serializer = null,
                BsonBinaryWriterSettings writerSettings = null,
                Action<BsonSerializationContext.Builder> configurator = null,
                BsonSerializationArgs args = default(BsonSerializationArgs)
                )
            {
                return ToBson(obj, typeof(TNominalType), writerSettings, serializer, configurator, args);
            }

            /// <summary>
            /// Serializes an object to a BSON byte array.
            /// </summary>
            /// <param name="obj">The object.</param>
            /// <param name="nominalType">The nominal type of the object..</param>
            /// <param name="writerSettings">The writer settings.</param>
            /// <param name="serializer">The serializer.</param>
            /// <param name="configurator">The serialization context configurator.</param>
            /// <param name="args">The serialization args.</param>
            /// <returns>A BSON byte array.</returns>
            /// <exception cref="System.ArgumentNullException">nominalType</exception>
            /// <exception cref="System.ArgumentException">serializer</exception>
            public static byte[] ToBson(
                this object obj,
                Type nominalType,
                BsonBinaryWriterSettings writerSettings = null,
                IBsonSerializer serializer = null,
                Action<BsonSerializationContext.Builder> configurator = null,
                BsonSerializationArgs args = default(BsonSerializationArgs))
            {
                if (nominalType == null)
                {
                    throw new ArgumentNullException("nominalType");
                }

                if (serializer == null)
                {
                    serializer = BsonSerializer.LookupSerializer(nominalType);
                }
                if (serializer.ValueType != nominalType)
                {
                    var message = string.Format("Serializer type {0} value type does not match document types {1}.", serializer.GetType().FullName, nominalType.FullName);
                    throw new ArgumentException(message, "serializer");
                }

                using (var memoryStream = new MemoryStream())
                {
                    using (var bsonWriter = new BsonBinaryWriter(memoryStream, writerSettings ?? BsonBinaryWriterSettings.Defaults))
                    {
                        var context = BsonSerializationContext.CreateRoot(bsonWriter, configurator);
                        args.NominalType = nominalType;
                        serializer.Serialize(context, args, obj);
                    }
                    return memoryStream.ToArray();
                }
            }

            /// <summary>
            /// Serializes an object to a BsonDocument.
            /// </summary>
            /// <typeparam name="TNominalType">The nominal type of the object.</typeparam>
            /// <param name="obj">The object.</param>
            /// <param name="serializer">The serializer.</param>
            /// <param name="configurator">The serialization context configurator.</param>
            /// <param name="args">The serialization args.</param>
            /// <returns>A BsonDocument.</returns>
            public static BsonDocument ToBsonDocument<TNominalType>(
                this TNominalType obj,
                IBsonSerializer<TNominalType> serializer = null,
                Action<BsonSerializationContext.Builder> configurator = null,
                BsonSerializationArgs args = default(BsonSerializationArgs))
            {
                return ToBsonDocument(obj, typeof(TNominalType), serializer, configurator, args);
            }

            /// <summary>
            /// Serializes an object to a BsonDocument.
            /// </summary>
            /// <param name="obj">The object.</param>
            /// <param name="nominalType">The nominal type of the object.</param>
            /// <param name="serializer">The serializer.</param>
            /// <param name="configurator">The serialization context configurator.</param>
            /// <param name="args">The serialization args.</param>
            /// <returns>A BsonDocument.</returns>
            /// <exception cref="System.ArgumentNullException">nominalType</exception>
            /// <exception cref="System.ArgumentException">serializer</exception>
            public static BsonDocument ToBsonDocument(
                this object obj,
                Type nominalType,
                IBsonSerializer serializer = null,
                Action<BsonSerializationContext.Builder> configurator = null,
                BsonSerializationArgs args = default(BsonSerializationArgs))
            {
                if (nominalType == null)
                {
                    throw new ArgumentNullException("nominalType");
                }

                if (obj == null)
                {
                    return null;
                }

                if (serializer == null)
                {
                    var bsonDocument = obj as BsonDocument;
                    if (bsonDocument != null)
                    {
                        return bsonDocument; // it's already a BsonDocument
                    }

                    var convertibleToBsonDocument = obj as IConvertibleToBsonDocument;
                    if (convertibleToBsonDocument != null)
                    {
                        return convertibleToBsonDocument.ToBsonDocument(); // use the provided ToBsonDocument method
                    }

                    serializer = BsonSerializer.LookupSerializer(nominalType);
                }
                if (serializer.ValueType != nominalType)
                {
                    var message = string.Format("Serializer type {0} value type does not match document types {1}.", serializer.GetType().FullName, nominalType.FullName);
                    throw new ArgumentException(message, "serializer");
                }

                // otherwise serialize into a new BsonDocument
                var document = new BsonDocument();
                using (var bsonWriter = new BsonDocumentWriter(document))
                {
                    var context = BsonSerializationContext.CreateRoot(bsonWriter, configurator);
                    args.NominalType = nominalType;
                    serializer.Serialize(context, args, obj);
                }
                return document;
            }

            /// <summary>
            /// Serializes an object to a JSON string.
            /// </summary>
            /// <typeparam name="TNominalType">The nominal type of the object.</typeparam>
            /// <param name="obj">The object.</param>
            /// <param name="writerSettings">The JsonWriter settings.</param>
            /// <param name="serializer">The serializer.</param>
            /// <param name="configurator">The serializastion context configurator.</param>
            /// <param name="args">The serialization args.</param>
            /// <returns>
            /// A JSON string.
            /// </returns>
            public static string ToMyJson<TNominalType>(
                this TNominalType obj,
                JsonWriterSettings writerSettings = null,
                IBsonSerializer<TNominalType> serializer = null,
                Action<BsonSerializationContext.Builder> configurator = null,
                BsonSerializationArgs args = default(BsonSerializationArgs))
            {
                return ToMyJson(obj, typeof(TNominalType), writerSettings, serializer, configurator, args);
            }

            /// <summary>
            /// Serializes an object to a JSON string.
            /// </summary>
            /// <param name="obj">The object.</param>
            /// <param name="nominalType">The nominal type of the objectt.</param>
            /// <param name="writerSettings">The JsonWriter settings.</param>
            /// <param name="serializer">The serializer.</param>
            /// <param name="configurator">The serialization context configurator.</param>
            /// <param name="args">The serialization args.</param>
            /// <returns>
            /// A JSON string.
            /// </returns>
            /// <exception cref="System.ArgumentNullException">nominalType</exception>
            /// <exception cref="System.ArgumentException">serializer</exception>
            public static string ToMyJson(
                this object obj,
                Type nominalType,
                JsonWriterSettings writerSettings = null,
                IBsonSerializer serializer = null,
                Action<BsonSerializationContext.Builder> configurator = null,
                BsonSerializationArgs args = default(BsonSerializationArgs))
            {
                if (nominalType == null)
                {
                    throw new ArgumentNullException("nominalType");
                }

                if (serializer == null)
                {
                    serializer = BsonSerializer.LookupSerializer(nominalType);
                }
                if (serializer.ValueType != nominalType)
                {
                    var message = string.Format("Serializer type {0} value type does not match document types {1}.", serializer.GetType().FullName, nominalType.FullName);
                    throw new ArgumentException(message, "serializer");
                }

                using (var stringWriter = new StringWriter())
                {
                    using (var bsonWriter = new JsonWriterMine(stringWriter, writerSettings ?? JsonWriterSettings.Defaults))
                    {
                        var context = BsonSerializationContext.CreateRoot(bsonWriter, configurator);
                        args.NominalType = nominalType;
                        serializer.Serialize(context, args, obj);
                    }
                    return stringWriter.ToString();
                }
            }
        }
    }

所以基本上，将整个类从 github 复制到您自己的类中，并将 2 个方法的名称:ToJson() 更改为您的方法之一。在这里你可以看到我的是 ToJsonMine()。

现在，到第二节课你需要:

JsonWriter

using MongoDB.Bson.IO;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using MongoDB.Bson;

namespace Fishing.MongoDB.Serializers
{
    public class JsonWriterMine : BsonWriter
    {

        // private fields
        private TextWriter _textWriter;
        private JsonWriterSettings _jsonWriterSettings; // same value as in base class just declared as derived class
        private InternalJsonWriterContext _context;

        // constructors
        /// <summary>
        /// Initializes a new instance of the JsonWriter class.
        /// </summary>
        /// <param name="writer">A TextWriter.</param>
        public JsonWriterMine(TextWriter writer)
            : this(writer, JsonWriterSettings.Defaults)
        {
        }

        /// <summary>
        /// Initializes a new instance of the JsonWriter class.
        /// </summary>
        /// <param name="writer">A TextWriter.</param>
        /// <param name="settings">Optional JsonWriter settings.</param>
        public JsonWriterMine(TextWriter writer, JsonWriterSettings settings)
            : base(settings)
        {
            if (writer == null)
            {
                throw new ArgumentNullException("writer");
            }

            _textWriter = writer;
            _jsonWriterSettings = settings; // already frozen by base class
            _context = new InternalJsonWriterContext(null, ContextType.TopLevel, "");
            State = BsonWriterState.Initial;
        }

 /// <summary>
    /// Writes a BSON DateTime to the writer.
    /// </summary>
    /// <param name="value">The number of milliseconds since the Unix epoch.</param>
    public override void WriteDateTime(long value)
    {
        if (Disposed) { throw new ObjectDisposedException("JsonWriter"); }
        if (State != BsonWriterState.Value && State != BsonWriterState.Initial)
        {
            ThrowInvalidState("WriteDateTime", BsonWriterState.Value, BsonWriterState.Initial);
        }

        WriteNameHelper(Name);
        switch (_jsonWriterSettings.OutputMode)
        {
            case JsonOutputMode.Strict:
                var utcDateTimeFirst = BsonUtils.ToDateTimeFromMillisecondsSinceEpoch(value);
                _textWriter.Write($"\"{utcDateTimeFirst.ToString("yyyy-MM-ddTHH:mm:ss.FFFZ")}\"");
                break;

            case JsonOutputMode.Shell:
            default:
                // use ISODate for values that fall within .NET's DateTime range, and "new Date" for all others
                if (value >= BsonConstants.DateTimeMinValueMillisecondsSinceEpoch &&
                    value <= BsonConstants.DateTimeMaxValueMillisecondsSinceEpoch)
                {
                    var utcDateTime = BsonUtils.ToDateTimeFromMillisecondsSinceEpoch(value);
                    _textWriter.Write("ISODate(\"{0}\")", utcDateTime.ToString("yyyy-MM-ddTHH:mm:ss.FFFZ"));
                }
                else
                {
                    _textWriter.Write("new Date({0})", value);
                }
                break;
        }

        State = GetNextState();
    }

    }
}

这就是魔法发生的地方。将整个类 JsonWriter 从 GitHub 复制到你自己的并给它一个新名称(扩展 BsonWriter nad 实现所有方法)。现在，您可以在这里操作您希望如何序列化日期。相应地更改 WriteDateTime(long value)。如您所见，在 case JsonOutputMode.Strict: 中，我将其更改为返回一个按我需要的方式格式化的 DateTime 对象。

最后，由于 MongoSerializer 具有名为 JsonWriterContext 的内部类，您需要创建自己的类并在 JsonWriter 中使用它(第 2 步)。

这是我的样子(你可以完整复制它):

using MongoDB.Bson.IO;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Fishing.MongoDB.Serializers
{
    public class InternalJsonWriterContext
    {
        // private fields
        private InternalJsonWriterContext _parentContext;
        private ContextType _contextType;
        private string _indentation;
        private bool _hasElements = false;

        // constructors
        internal InternalJsonWriterContext(InternalJsonWriterContext parentContext, ContextType contextType, string indentChars)
        {
            _parentContext = parentContext;
            _contextType = contextType;
            _indentation = (parentContext == null) ? indentChars : parentContext.Indentation + indentChars;
        }

        // internal properties
        internal InternalJsonWriterContext ParentContext
        {
            get { return _parentContext; }
        }

        internal ContextType ContextType
        {
            get { return _contextType; }
        }

        internal string Indentation
        {
            get { return _indentation; }
        }

        internal bool HasElements
        {
            get { return _hasElements; }
            set { _hasElements = value; }
        }
    }
}

在你拥有一切之后，你将在 MongoCursorJsonConverter(第一步)中看到，在第二个 ToJsonMine() 方法中，我有这一行:

 using (var bsonWriter = new JsonWriterMine(stringWriter, writerSettings ?? JsonWriterSettings.Defaults))

您只需将其替换为您在第 2 步中创建的自己的自定义类，它就会非常有效。

最后，您只需调用:

var lists = mongoListBatch.ToJson(settings);

它会序列化你在 WriteDate(long value)

关于c# - Mongo C# 驱动 toJson() DateTime，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46847042/