KinSlayerUY的自定义属性为我工作得很好，但我有复杂类型的问题。它们在属性代码中被映射为实体，因此不能被映射为ComplexType。

因此，我扩展了代码以允许这样做:

public static void OnModelCreating(DbModelBuilder modelBuilder)
    {
        foreach (Type classType in from t in Assembly.GetAssembly(typeof(DecimalPrecisionAttribute)).GetTypes()
                                   where t.IsClass && t.Namespace == "FA.f1rstval.Data"
                                   select t)
        {
            foreach (var propAttr in classType.GetProperties(BindingFlags.Public | BindingFlags.Instance).Where(p => p.GetCustomAttribute<DecimalPrecisionAttribute>() != null).Select(
                   p => new { prop = p, attr = p.GetCustomAttribute<DecimalPrecisionAttribute>(true) }))
            {

                ParameterExpression param = ParameterExpression.Parameter(classType, "c");
                Expression property = Expression.Property(param, propAttr.prop.Name);
                LambdaExpression lambdaExpression = Expression.Lambda(property, true,
                                                                         new ParameterExpression[] { param });
                DecimalPropertyConfiguration decimalConfig;
                int MethodNum;
                if (propAttr.prop.PropertyType.IsGenericType && propAttr.prop.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
                {
                    MethodNum = 7;
                }
                else
                {
                    MethodNum = 6;
                }

                //check if complextype
                if (classType.GetCustomAttribute<ComplexTypeAttribute>() != null)
                {
                    var complexConfig = modelBuilder.GetType().GetMethod("ComplexType").MakeGenericMethod(classType).Invoke(modelBuilder, null);
                    MethodInfo methodInfo = complexConfig.GetType().GetMethods().Where(p => p.Name == "Property").ToList()[MethodNum];
                    decimalConfig = methodInfo.Invoke(complexConfig, new[] { lambdaExpression }) as DecimalPropertyConfiguration;
                }
                else
                {
                    var entityConfig = modelBuilder.GetType().GetMethod("Entity").MakeGenericMethod(classType).Invoke(modelBuilder, null);
                    MethodInfo methodInfo = entityConfig.GetType().GetMethods().Where(p => p.Name == "Property").ToList()[MethodNum];
                    decimalConfig = methodInfo.Invoke(entityConfig, new[] { lambdaExpression }) as DecimalPropertyConfiguration;
                }

                decimalConfig.HasPrecision(propAttr.attr.Precision, propAttr.attr.Scale);
            }
        }
    }

实体框架6 (Alpha, rc1)有一些叫做自定义约定的东西。设置十进制精度。

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Properties<decimal>().Configure(config => config.HasPrecision(18, 4));
}

参考:

http://entityframework.codeplex.com/wikipage?title=Custom%20Conventions http://weblogs.asp.net/scottgu/archive/2012/12/11/entity-framework-6-alpha2-now-available.aspx

在EF6

modelBuilder.Properties()
    .Where(x => x.GetCustomAttributes(false).OfType<DecimalPrecisionAttribute>().Any())
    .Configure(c => {
        var attr = (DecimalPrecisionAttribute)c.ClrPropertyInfo.GetCustomAttributes(typeof (DecimalPrecisionAttribute), true).FirstOrDefault();

        c.HasPrecision(attr.Precision, attr.Scale);
    });

[Column(TypeName = "decimal(18,2)")]

这将与EF Core代码首次迁移一起工作，如下所述。

你总是可以告诉EF在OnModelCreating函数中的Context类中使用约定来做到这一点，如下所示:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    // <... other configurations ...>
    // modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
    // modelBuilder.Conventions.Remove<ManyToManyCascadeDeleteConvention>();
    // modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();

    // Configure Decimal to always have a precision of 18 and a scale of 4
    modelBuilder.Conventions.Remove<DecimalPropertyConvention>();
    modelBuilder.Conventions.Add(new DecimalPropertyConvention(18, 4));

    base.OnModelCreating(modelBuilder);
}

这只适用于Code First EF fyi，并适用于映射到db的所有十进制类型。

如果你想在EF6中设置所有小数的精度，你可以替换DbModelBuilder中使用的默认DecimalPropertyConvention约定:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Conventions.Remove<DecimalPropertyConvention>();
    modelBuilder.Conventions.Add(new DecimalPropertyConvention(38, 18));
}

EF6中的默认DecimalPropertyConvention将十进制属性映射为十进制(18,2)列。

如果你只想让单个属性具有指定的精度，那么你可以在DbModelBuilder中为实体的属性设置精度:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<MyEntity>().Property(e => e.Value).HasPrecision(38, 18);
}

或者，为指定精度的实体添加一个EntityTypeConfiguration<>:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Configurations.Add(new MyEntityConfiguration());
}

internal class MyEntityConfiguration : EntityTypeConfiguration<MyEntity>
{
    internal MyEntityConfiguration()
    {
        this.Property(e => e.Value).HasPrecision(38, 18);
    }
}