从数据库加载时，DateTime.Kind 设置为未指定，而不是 UTC [英] DateTime.Kind set to unspecified, not UTC, upon loading from database

问题描述

当我创建一个 Buyin 对象时，来自 ASP.NET MVC 控制器的响应，(return Json(response, JsonRequestBehavior.AllowGet);，如下所示:

买入":{身份证":95，玩家会话 ID":88，玩家 ID":45，"玩家姓名": "艾伦",金额":888，"BuyinType": "信用",描述":空，授权":真实，"SignPath": "~/Signs/Buyins\95.png",付款":空，创建日期":/日期(1477242738042)/"},

如果我在

但是 Kind 设置为 Unspecified 所以我认为这是导致问题的原因.

目前我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，有没有办法告诉服务器加载日期，Kind 设置为 UTC 我认为这是问题所在?

使用实体框架保存和加载数据库.

接受答案后更新

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

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

解决方案

假设您使用的是 EF6 并且想要设置从数据库到Utc.

有人问过类似的问题，答案往往建议与 ObjectContext.ObjectMaterialized 事件，但它不会为使用投影的查询触发.

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

为了做到这一点，我们需要一个自定义的 DbDataReader 实现来拦截 GetDateTime 方法.不幸的是，实现 DbDataReader 派生类需要大量样板代码.幸运的是，我已经创建了一个基类作为我对 Dynamic 的回答转换以避免 C# 语法错误，它只是将每个方法委托给底层的 DbDataReader 实例，所以我将从那里开始:

抽象类 DelegatingDbDataReader : DbDataReader{只读 DbDataReader 源；public DelegatingDbDataReader(DbDataReader 源){this.source = 来源；}公共覆盖对象 this[string name] { get { return source[name];} }公共覆盖对象 this[int ordinal] { get { return source[ordinal];} }公共覆盖 int Depth { get { return source.Depth;} }公共覆盖 int FieldCount { get { return source.FieldCount;} }public override bool HasRows { get { return source.HasRows; }} }公共覆盖 bool IsClosed { get { return source.IsClosed;} }公共覆盖 int RecordsAffected { get { return source.RecordsAffected;} }public override bool GetBoolean(int ordinal) { return source.GetBoolean(ordinal);}公共覆盖字节 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);}公共覆盖字符 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);}公共覆盖字符串 GetDataTypeName(int ordinal) { return source.GetDataTypeName(ordinal);}公共覆盖 DateTime GetDateTime(int ordinal) { return source.GetDateTime(ordinal);}公共覆盖十进制 GetDecimal(int ordinal) { return source.GetDecimal(ordinal);}公共覆盖双 GetDouble(int ordinal) { return source.GetDouble(ordinal);}公共覆盖 IEnumerator GetEnumerator() { return source.GetEnumerator();}公共覆盖类型 GetFieldType(int ordinal) { return source.GetFieldType(ordinal);}公共覆盖浮动 GetFloat(int ordinal) { return source.GetFloat(ordinal);}公共覆盖 Guid GetGuid(int ordinal) { return source.GetGuid(ordinal);}public override short GetInt16(int ordinal) { return source.GetInt16(ordinal);}公共覆盖 int GetInt32(int ordinal) { return source.GetInt32(ordinal);}公共覆盖长 GetInt64(int ordinal) { return source.GetInt64(ordinal);}公共覆盖字符串 GetName(int ordinal) { return source.GetName(ordinal);}public override int GetOrdinal(string name) { return source.GetOrdinal(name);}公共覆盖字符串 GetString(int ordinal) { return source.GetString(ordinal);}公共覆盖对象 GetValue(int ordinal) { return source.GetValue(ordinal);}公共覆盖 int GetValues(object[] values) { return source.GetValues(values);}public override bool IsDBNull(int ordinal) { return source.IsDBNull(ordinal);}公共覆盖 bool NextResult() { return source.NextResult();}public override bool Read() { return source.Read();}public override void Close() { source.Close();}public override T GetFieldValue(int ordinal) { return source.GetFieldValue(ordinal);}公共覆盖任务 TGetFieldValueAsync<T>(int ordinal, CancellationTokenCancellationToken) { return source.GetFieldValueAsync<T>(ordinal, cancelToken);}公共覆盖类型 GetProviderSpecificFieldType(int ordinal) { return source.GetProviderSpecificFieldType(ordinal);}公共覆盖对象 GetProviderSpecificValue(int ordinal) { return source.GetProviderSpecificValue(ordinal);}公共覆盖 int GetProviderSpecificValues(object[] values) { return source.GetProviderSpecificValues(values);}公共覆盖数据表 GetSchemaTable() { return source.GetSchemaTable();}公共覆盖流 GetStream(int ordinal) { return source.GetStream(ordinal);}公共覆盖 TextReader GetTextReader(int ordinal) { return source.GetTextReader(ordinal);}公共覆盖任务IsDBNullAsync(int ordinal, CancellationTokenCancellationToken) { return source.IsDBNullAsync(ordinal, cancelToken);}公共覆盖任务ReadAsync(CancellationToken cancelationToken) { return source.ReadAsync(cancellationToken);}公共覆盖 int VisibleFieldCount { get { return source.VisibleFieldCount;} }}

并在其上构建我们需要的实际类:

class UtcDateTimeConvertingDbDataReader : DelegatingDbDataReader{公共 UtcDateTimeConvertingDbDataReader(DbDataReader source) : base(source) { }公共覆盖 DateTime GetDateTime(int ordinal){返回 DateTime.SpecifyKind(base.GetDateTime(ordinal), DateTimeKind.Utc);}}

一旦我们有了它，我们需要使用 EF 拦截将它插入到 EF 基础设施中.

我们将首先创建一个自定义的 DbCommandInterceptor 派生类:

class UtcDateTimeConvertingDbCommandInterceptor : DbCommandInterceptor{public override void ReaderExecuted(DbCommand command, DbCommandInterceptionContextinterceptionContext){base.ReaderExecuted(命令，interceptionContext)；if (!(interceptionContext.Result is UtcDateTimeConvertingDbDataReader)&&拦截Context.Result != null&&拦截Context.Exception == null)拦截上下文.结果 = 新的 UtcDateTimeConvertingDbDataReader(interceptionContext.Result);}}

注册它(例如从你的 DbContext 派生类静态构造函数):

公共类 YourDbContext : DbContext{静态 YourDbContext(){DbInterception.Add(new UtcDateTimeConvertingDbCommandInterceptor());}//...}

我们就完成了.

现在来自数据库的每个 DateTime 值都会将 Kind 属性设置为 Utc.

When I create a Buyin object the response from the ASP.NET MVC controller, (return Json(response, JsonRequestBehavior.AllowGet);, looks like this:

"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)/"
    },

If I convert that on Epoch Converter I get this time: GMT: Sun, 23 Oct 2016 17:12:18.042 GMT

Looking in the database the stored datetime seems to be correct:

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

When the response is sent out the Kind is set to UTC.

Now I call a controller to get all my data and all of the dates have several hours added to it:

 {
    "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

However when I request this object I can see that the actual object has the correct date set:

But the Kind is set to Unspecified so I think this is causing the problem.

For the moment I don't have not set any globalization settings.

So basically my question is: When ASP.NET MVC loads the dates from the database is there a way to tell the server to load the dates with Kind set to UTC as I think that is the problem?

The database is saved and loaded using Entity Framework.

Update after the accepted answer

The accepted answer was great however my date values was already stored in the Database as UTC dates so I modified GetDateTime to this:

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();
}

解决方案

Assuming you are using EF6 and you want to set the Kind property of any DateTime value retrieved from the database to Utc.

Similar questions have been asked, and the answers tend to suggest hooking into the ObjectContext.ObjectMaterialized event, but it didn't fire for queries that use projection.

The solution I'm going to propose works for both entity and projection queries, by performing the conversion at the DbDataReader level (which is used by this type of queries).

In order to do that, we need a custom DbDataReader implementation that intercepts the GetDateTime method. Unfortunately implementing DbDataReader derived class requires a lot of boilerplate code. Luckily I already created a base class form my answer to Dynamic Translate to avoid C# syntax errors which simply delegates each method to the underlying DbDataReader instance, so I'll just take it from there:

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; } }
}

and build the actual class that we need on top of it:

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

Once we have that, we need to plug it into EF infrastructure using EF interception.

We'll start by creating a custom DbCommandInterceptor derived class:

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

register it (for instance from your DbContext derived class static constructor):

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

and we are done.

Now every DateTime value coming from the database will have Kind property set to Utc.

这篇关于从数据库加载时，DateTime.Kind 设置为未指定，而不是 UTC的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！