从数据库加载时,DateTime.Kind设置为未指定,而不是UTC

Question

当我Buyin从ASP.NET MVC控制器创建一个对象的响应时,(return Json(response, JsonRequestBehavior.AllowGet);看起来像这样:

"Buyin": {
        "Id": 95,
        "PlayerSessionId": 88,
        "PlayerId": 45,
        "PlayerName": "Alan",
        "Amount": 888,
        "BuyinType": "Credits",
        "Description": null,
        "Authorized": true,
        "SignPath": "~/Signs/Buyins\\95.png",
        "Payment": null,
        "CreationDate": "/Date(1477242738042)/"
    },

如果我在Epoch Converter上转换它,我会得到这个时间:GMT: Sun, 23 Oct 2016 17:12:18.042 GMT

在数据库中查看存储的日期时间似乎是正确的:

95  NULL    1   1   2016-10-23 17:12:18.043

发送响应时,Kind将设置为UTC.

现在我调用一个控制器来获取我的所有数据,并且所有日期都有几个小时添加到它:

 {
    "Id": 95,
    "PlayerSessionId": 88,
    "PlayerId": 45,
    "PlayerName": "Alan",
    "Amount": 888,
    "BuyinType": "Credits",
    "Description": null,
    "Authorized": true,
    "SignPath": "~/Signs/Buyins\\95.png",
    "Payment": null,
    "CreationDate": "/Date(1477267938043)/"
}

1477267938043 = GMT: Mon, 24 Oct 2016 00:12:18.043 GMT

但是,当我请求此对象时,我可以看到实际对象具有正确的日期设置:

但这Kind是设定的,Unspecified所以我认为这是导致问题的原因.

目前我还没有设置任何全球化设置.

所以基本上我的问题是:当ASP.NET MVC从数据库加载日期时有一种方法告诉服务器加载日期Kind设置UTC为我认为这是问题吗？

使用Entity Framework保存和加载数据库.

在接受的答案后更新

接受的答案很棒但是我的日期值已经作为UTC日期存储在数据库中,所以我修改GetDateTime为:

public override DateTime GetDateTime(int ordinal)
{
    var date = base.GetDateTime(ordinal);
    var utcDate = DateTime.SpecifyKind(date, DateTimeKind.Utc);
    return utcDate;
    //return base.GetDateTime(ordinal).ToUniversalTime();
}

Answer 1

假设您正在使用EF6,并且您想要将从数据库检索到的Kind任何DateTime值的属性设置为Utc.

已经提出了类似的问题,答案倾向于暗示ObjectContext.ObjectMaterialized事件,但它并没有触发使用投影的查询.

我将提出的解决方案适用于实体和投影查询,通过在DbDataReader级别执行转换(由此类查询使用).

为了做到这一点,我们需要一个DbDataReader截取GetDateTime方法的自定义实现.不幸的是,实现DbDataReader派生类需要大量的样板代码.幸运的是,我已经创建了一个基类来形成我对Dynamic Translate的回答,以避免C#语法错误,它只是将每个方法委托给底层DbDataReader实例,所以我将从那里开始:

abstract class DelegatingDbDataReader : DbDataReader
{
    readonly DbDataReader source;
    public DelegatingDbDataReader(DbDataReader source)
    {
        this.source = source;
    }
    public override object this[string name] { get { return source[name]; } }
    public override object this[int ordinal] { get { return source[ordinal]; } }
    public override int Depth { get { return source.Depth; } }
    public override int FieldCount { get { return source.FieldCount; } }
    public override bool HasRows { get { return source.HasRows; } }
    public override bool IsClosed { get { return source.IsClosed; } }
    public override int RecordsAffected { get { return source.RecordsAffected; } }
    public override bool GetBoolean(int ordinal) { return source.GetBoolean(ordinal); }
    public override byte GetByte(int ordinal) { return source.GetByte(ordinal); }
    public override long GetBytes(int ordinal, long dataOffset, byte[] buffer, int bufferOffset, int length) { return source.GetBytes(ordinal, dataOffset, buffer, bufferOffset, length); }
    public override char GetChar(int ordinal) { return source.GetChar(ordinal); }
    public override long GetChars(int ordinal, long dataOffset, char[] buffer, int bufferOffset, int length) { return source.GetChars(ordinal, dataOffset, buffer, bufferOffset, length); }
    public override string GetDataTypeName(int ordinal) { return source.GetDataTypeName(ordinal); }
    public override DateTime GetDateTime(int ordinal) { return source.GetDateTime(ordinal); }
    public override decimal GetDecimal(int ordinal) { return source.GetDecimal(ordinal); }
    public override double GetDouble(int ordinal) { return source.GetDouble(ordinal); }
    public override IEnumerator GetEnumerator() { return source.GetEnumerator(); }
    public override Type GetFieldType(int ordinal) { return source.GetFieldType(ordinal); }
    public override float GetFloat(int ordinal) { return source.GetFloat(ordinal); }
    public override Guid GetGuid(int ordinal) { return source.GetGuid(ordinal); }
    public override short GetInt16(int ordinal) { return source.GetInt16(ordinal); }
    public override int GetInt32(int ordinal) { return source.GetInt32(ordinal); }
    public override long GetInt64(int ordinal) { return source.GetInt64(ordinal); }
    public override string GetName(int ordinal) { return source.GetName(ordinal); }
    public override int GetOrdinal(string name) { return source.GetOrdinal(name); }
    public override string GetString(int ordinal) { return source.GetString(ordinal); }
    public override object GetValue(int ordinal) { return source.GetValue(ordinal); }
    public override int GetValues(object[] values) { return source.GetValues(values); }
    public override bool IsDBNull(int ordinal) { return source.IsDBNull(ordinal); }
    public override bool NextResult() { return source.NextResult(); }
    public override bool Read() { return source.Read(); }
    public override void Close() { source.Close(); }
    public override T GetFieldValue<T>(int ordinal) { return source.GetFieldValue<T>(ordinal); }
    public override Task<T> GetFieldValueAsync<T>(int ordinal, CancellationToken cancellationToken) { return source.GetFieldValueAsync<T>(ordinal, cancellationToken); }
    public override Type GetProviderSpecificFieldType(int ordinal) { return source.GetProviderSpecificFieldType(ordinal); }
    public override object GetProviderSpecificValue(int ordinal) { return source.GetProviderSpecificValue(ordinal); }
    public override int GetProviderSpecificValues(object[] values) { return source.GetProviderSpecificValues(values); }
    public override DataTable GetSchemaTable() { return source.GetSchemaTable(); }
    public override Stream GetStream(int ordinal) { return source.GetStream(ordinal); }
    public override TextReader GetTextReader(int ordinal) { return source.GetTextReader(ordinal); }
    public override Task<bool> IsDBNullAsync(int ordinal, CancellationToken cancellationToken) { return source.IsDBNullAsync(ordinal, cancellationToken); }
    public override Task<bool> ReadAsync(CancellationToken cancellationToken) { return source.ReadAsync(cancellationToken); }
    public override int VisibleFieldCount { get { return source.VisibleFieldCount; } }
}

并构建我们需要的实际类:

class UtcDateTimeConvertingDbDataReader : DelegatingDbDataReader
{
    public UtcDateTimeConvertingDbDataReader(DbDataReader source) : base(source) { }
    public override DateTime GetDateTime(int ordinal)
    {
        return DateTime.SpecifyKind(base.GetDateTime(ordinal), DateTimeKind.Utc);
    }
}

一旦我们有了这个,我们需要使用EF 拦截将其插入EF基础设施.

我们首先创建一个自定义DbCommandInterceptor派生类:

class UtcDateTimeConvertingDbCommandInterceptor : DbCommandInterceptor
{
    public override void ReaderExecuted(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
        base.ReaderExecuted(command, interceptionContext);
        if (interceptionContext.Result != null && interceptionContext.Exception == null)
            interceptionContext.Result = new UtcDateTimeConvertingDbDataReader(interceptionContext.Result);
    }
}

注册它(例如从你的DbContext派生类静态构造函数):

public class YourDbContext : DbContext
{
    static YourDbContext()
    {
        DbInterception.Add(new UtcDateTimeConvertingDbCommandInterceptor());
    }
    // ...
}

我们完成了.

现在DateTime,来自数据库的每个值都将Kind属性设置为Utc.