代码之家 › 专栏 › 技术社区 › Sander Rijken

确保DateTime属性返回DateTimeKind.Utc

.net-4.0 linq-to-entities entity-framework

Sander Rijken · 技术社区 · 15 年前

Kind == DateTimeKind.Utc

如果可能使用t4,请描述如何更改属性。当前,属性生成为:

[EdmScalarPropertyAttribute(EntityKeyProperty=false, IsNullable=false)]
[DataMemberAttribute()]
public global::System.DateTime Created
{
    get
    {
        return _created;
    }
    internal set
    {
        OnCreatedChanging(value);
        ReportPropertyChanging("Created");
        _created = StructuralObject.SetValidValue(value);
        ReportPropertyChanged("Created");
        OnCreatedChanged();
    }
}
private global::System.DateTime _created;
partial void OnCreatedChanging(global::System.DateTime value);
partial void OnCreatedChanged();

3 回复 | 直到 15 年前

aarondcoleman 13 年前

在我们的案例中,始终指定DateTimeKind是不切实际的,如前所述:

DateTime utcDateTime = DateTime.SpecifyKind(databaseDateTime, DateTimeKind.Utc);

http://www.aaroncoleman.net/post/2011/06/16/Forcing-Entity-Framework-to-mark-DateTime-fields-at-UTC.aspx

简言之:

1) 为.edmx模型创建.tt文件

2) 打开.tt文件并找到“WritePrimitiveTypeProperty”方法。

ReportPropertyChanging 和 ReportPropertyChanged

<#+ if( ((PrimitiveType)primitiveProperty.TypeUsage.EdmType).PrimitiveTypeKind == PrimitiveTypeKind.DateTime)
            {
#>
        if(<#=code.FieldName(primitiveProperty)#> == new DateTime())
        {
            <#=code.FieldName(primitiveProperty)#> = StructuralObject.SetValidValue(value<#=OptionalNullableParameterForSetValidValue(primitiveProperty, code)#>);
<#+ 
            if(ef.IsNullable(primitiveProperty))
            {  
#>              
            if(value != null)
                <#=code.FieldName(primitiveProperty)#> = DateTime.SpecifyKind(<#=code.FieldName(primitiveProperty)#>.Value, DateTimeKind.Utc);
<#+             } 
            else
            {#>
            <#=code.FieldName(primitiveProperty)#> = DateTime.SpecifyKind(<#=code.FieldName(primitiveProperty)#>, DateTimeKind.Utc);                
<#+ 
            } 
#>
        }
        else
        {
            <#=code.FieldName(primitiveProperty)#> = StructuralObject.SetValidValue(value<#=OptionalNullableParameterForSetValidValue(primitiveProperty, code)#>);
        }
<#+ 
        }
        else
        {
#>
    <#=code.FieldName(primitiveProperty)#> = StructuralObject.SetValidValue(value<#=OptionalNullableParameterForSetValidValue(primitiveProperty, code)#>);
<#+ 
        }
#>

Community CDub 7 年前

我使用了与Michael相同的方法(参见其他博客文章: https://stackoverflow.com/a/9386364/1069313 )直到那时,我才深入一点,使用反射搜索DateTime和DateTime?

public static void ReadAllDateTimeValuesAsUtc(this DbContext context)
{
        ((IObjectContextAdapter)context).ObjectContext.ObjectMaterialized += ReadAllDateTimeValuesAsUtc;
}

private static void ReadAllDateTimeValuesAsUtc(object sender, ObjectMaterializedEventArgs e)
{
    //Extract all DateTime properties of the object type
    var properties = e.Entity.GetType().GetProperties()
        .Where(property => property.PropertyType == typeof (DateTime) ||
                           property.PropertyType == typeof (DateTime?)).ToList();
    //Set all DaetTimeKinds to Utc
    properties.ForEach(property => SpecifyUtcKind(property, e.Entity));
}

private static void SpecifyUtcKind(PropertyInfo property, object value)
{
    //Get the datetime value
    var datetime = property.GetValue(value, null);

    //set DateTimeKind to Utc
    if (property.PropertyType == typeof(DateTime))
    {
        datetime = DateTime.SpecifyKind((DateTime) datetime, DateTimeKind.Utc);
    }
    else if(property.PropertyType == typeof(DateTime?))
    {
        var nullable = (DateTime?) datetime;
        if(!nullable.HasValue) return;
        datetime = (DateTime?)DateTime.SpecifyKind(nullable.Value, DateTimeKind.Utc);
    }
    else
    {
        return;
    }

    //And set the Utc DateTime value
    property.SetValue(value, datetime, null);
}

然后我转到我的WebsiteReadModelContext的构造函数,它是一个DbContext对象,并调用ReadAllDateTimeValuesAsUtc方法

public WebsiteReadModelContext()
{
      this.ReadAllDateTimeValuesAsUtc();
}

John Farrell 15 年前

是的,可以使用自定义T4模板。

尝试POCO方法可能更容易;

对于EF1: http://code.msdn.microsoft.com/EFPocoAdapter/Release/ProjectReleases.aspx?ReleaseId=1580

对于EF4: http://thedatafarm.com/blog/data-access/agile-entity-framework-4-repository-part-1-model-and-poco-classes/