我正在试验这种代码优先的方法,但我现在发现类型System的属性。Decimal被映射到Decimal(18,0)类型的sql列。
如何设置数据库列的精度?
我正在试验这种代码优先的方法,但我现在发现类型System的属性。Decimal被映射到Decimal(18,0)类型的sql列。
如何设置数据库列的精度?
当前回答
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);
});
其他回答
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);
}
}
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);
}
}
}
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。
您可以在实体数据模型的MSDN方面找到更多信息。 http://msdn.microsoft.com/en-us/library/ee382834.aspx 完整的建议。
这就是我正在寻找的,适用于普通的MVC项目(没有。net核心)
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<YOUR_CLASS_NAME>().Property(x => x.YOUR_DECIAML_PROP).HasPrecision(18, 6);
base.OnModelCreating(modelBuilder);
}
}
包管理器控制台
add-migration changeDecimalPrecision
生成的迁移
public override void Up()
{
AlterColumn("dbo.YOUR_CLASS_NAME", "YOUR_DECIAML_PROP", c => c.Decimal(nullable: false, precision: 18, scale: 6));
}