EF 7為DateTime列設置初始默認值

c# entity-framework-core

我需要能夠設置DateTime列的初始值。

當我指定“getutcdate()或DateTime.UtcNow時

entity.Property(e => e.ShipDate).DefaultValue("getutcdate()")
entity.Property(e => e.ShipDate).DefaultValue(DateTime.UtcNow)

然後運行dnx . ef migration add InitialMigration EF使用以下命令生成遷移快照:

b.Property<DateTime?>("ShipDate")
  .Required()
  .Annotation("Relational:ColumnDefaultValue", "getutcdate()")
  .Annotation("Relational:ColumnDefaultValueType", "System.String");

當我使用DateTime.UtcNow ...

b.Property<DateTime?>("ShipDate")
  .Annotation("Relational:ColumnDefaultValue", "635754129448768827")
  .Annotation("Relational:ColumnDefaultValueType", "System.DateTime");

和初始遷移:

ShipDate = table.Column(
  type: "datetime2", 
  nullable: false, 
  defaultValue: "getutcdate()"),

當我使用DateTime.UtcNow ...

ShipDate = table.Column(
  type: "datetime2", 
  nullable: true, 
  defaultValue: new DateTime(2015, 8, 17, 12, 55, 44, 876, DateTimeKind.Unspecified)),

看起來它必須工作,但是當我將數據插入表中時,列的默認值是創建時間戳的“即時”。

我錯過了什麼嗎?

另外,既然如此,如何在EF7中指定IDENTITY SEED?

謝謝

更新生成sql腳本後,我得到兩個選項:

如果使用“getutcdate()”:

[ShipDate] datetime2 DEFAULT 'getutcdate()',

由於引號不起作用

或者如果使用DateTime.utcNow:

[ShipDate] datetime2 DEFAULT '2015-08-17 12:55:44.8760000'

這解釋了我得到的靜態價值。

我想我可以用這個來管理。這是一個錯誤還是有正確的方法嗎?謝謝

一般承認的答案

您想要設置默認值SQL,而不是常量值:

entity.Property(e => e.ShipDate).HasDefaultValueSql("getutcdate()");

熱門答案

使用EF Core屬性的更靈活的解決方案:

在你的DbContext中:

protected override void OnModelCreating(ModelBuilder builder)
{
    base.OnModelCreating(builder);
    // Add your customizations after calling base.OnModelCreating(builder);
    CustomDataTypeAttributeConvention.Apply(builder);
    DecimalPrecisionAttributeConvention.Apply(builder);
    SqlDefaultValueAttributeConvention.Apply(builder);
}

並創建這些類:

public static class SqlDefaultValueAttributeConvention
{
    public static void Apply(ModelBuilder builder)
    {
        ConventionBehaviors
            .SetSqlValueForPropertiesWithAttribute<SqlDefaultValueAttribute>(builder, x => x.DefaultValue);
    }
}

public static class DecimalPrecisionAttributeConvention
{
    public static void Apply(ModelBuilder builder)
    {
        ConventionBehaviors
            .SetTypeForPropertiesWithAttribute<DecimalPrecisionAttribute>(builder,
                x => $"decimal({x.Precision}, {x.Scale})");
    }
}

public class CustomDataTypeAttributeConvention
{
    public static void Apply(ModelBuilder builder)
    {
        ConventionBehaviors
            .SetTypeForPropertiesWithAttribute<DataTypeAttribute>(builder,
                x => x.CustomDataType);
    }
}

public static class ConventionBehaviors
{
    public static void SetTypeForPropertiesWithAttribute<TAttribute>(ModelBuilder builder, Func<TAttribute, string> lambda) where TAttribute : class
    {
        SetPropertyValue<TAttribute>(builder).ForEach((x) => {
            x.Item1.Relational().ColumnType = lambda(x.Item2);
        });
    }

    public static void SetSqlValueForPropertiesWithAttribute<TAttribute>(ModelBuilder builder, Func<TAttribute, string> lambda) where TAttribute : class
    {
        SetPropertyValue<TAttribute>(builder).ForEach((x) =>
        {
            x.Item1.Relational().DefaultValueSql = lambda(x.Item2);
        });
    }

    private static List<Tuple<IMutableProperty, TAttribute>> SetPropertyValue<TAttribute>(ModelBuilder builder) where TAttribute : class
    {
        var propsToModify = new List<Tuple<IMutableProperty, TAttribute>>();
        foreach (var entity in builder.Model.GetEntityTypes())
        {
            var properties = entity.GetProperties();
            foreach (var property in properties)
            {
                var attribute = property.PropertyInfo
                    .GetCustomAttributes(typeof(TAttribute), false)
                    .FirstOrDefault() as TAttribute;
                if (attribute != null)
                {
                    propsToModify.Add(new Tuple<IMutableProperty, TAttribute>(property, attribute));
                }
            }
        }
        return propsToModify;
    }
}

和自定義屬性:

/// <summary>
/// Set a default value defined on the sql server
/// </summary>
[AttributeUsage(AttributeTargets.Property, Inherited = false, AllowMultiple = false)]
public class SqlDefaultValueAttribute : Attribute
{
    /// <summary>
    /// Default value to apply
    /// </summary>
    public string DefaultValue { get; set; }

    /// <summary>
    /// Set a default value defined on the sql server
    /// </summary>
    /// <param name="value">Default value to apply</param>
    public SqlDefaultValueAttribute(string value)
    {
        DefaultValue = value;
    }
}

/// <summary>
/// Set the decimal precision of a decimal sql data type
/// </summary>
[AttributeUsage(AttributeTargets.Property, Inherited = false, AllowMultiple = false)]
public class DecimalPrecisionAttribute : Attribute
{
    /// <summary>
    /// Specify the precision - the number of digits both left and right of the decimal
    /// </summary>
    public int Precision { get; set; }

    /// <summary>
    /// Specify the scale - the number of digits to the right of the decimal
    /// </summary>
    public int Scale { get; set; }

    /// <summary>
    /// Set the decimal precision of a decimal sql data type
    /// </summary>
    /// <param name="precision">Specify the precision - the number of digits both left and right of the decimal</param>
    /// <param name="scale">Specify the scale - the number of digits to the right of the decimal</param>
    public DecimalPrecisionAttribute(int precision, int scale)
    {
        Precision = precision;
        Scale = scale;
    }

    public DecimalPrecisionAttribute(int[] values)
    {
        Precision = values[0];
        Scale = values[1];
    }
}

然後,您將能夠使用這些屬性中的任何屬性裝飾您的表屬性(或自己製作自定義屬性):

[DecimalPrecision(18, 9)] [SqlDefaultValue("getutcdate()")] [DecimalPrecision(18, 9)] [SqlDefaultValue("getutcdate()")] [DataType("decimal(18,9)")]



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