在实体框架领域最大长度 [英] Field max length in Entity framework

问题描述

我需要把一个最大长度在我的测试领域使用ASP.NET MVC实体框架我的意见，我无法找到如何获得一个varchar字段的最大长度。

I need to put a max length on my test field on my Views using ASP.NET MVC with the Entity Framework and I can't find how to get the max length of a varchar field.

有没有一种简单的方法来获取，或数据库字段的任何其他财产

Is there an easy way to get that, or any other property of a database field

推荐答案

下面是我如何管理做（与实体扩展方法）：

Here is how i manage to do it (with an extension method on entities) :

public static int? GetMaxLength(this EntityObject entite, string nomPropriete)
    {
        int? result = null;
        using (XEntities contexte = XEntities.GetCurrentContext())
        {
            var queryResult = from meta in contexte.MetadataWorkspace.GetItems(DataSpace.CSpace)
                               .Where(m => m.BuiltInTypeKind == BuiltInTypeKind.EntityType)
                              from p in (meta as EntityType).Properties
                                 .Where(p => p.DeclaringType.Name == entite.GetType().Name
                                     && p.Name == nomPropriete
                                     && p.TypeUsage.EdmType.Name == "String")
                              select p.TypeUsage.Facets["MaxLength"].Value;
            if (queryResult.Count() > 0)
            {
                result = Convert.ToInt32(queryResult.First());
            }
        }
        return result;
    }

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