实体框架代码优先：如何映射私有字段？
是否可以将表列映射到类字段而不是类属性以及如何映射？
你可以做到:)
这个这是一个常见的要求，而且确实有道理；我们需要使用 LINQ 表达式和一些反射魔法。首先，用于返回指向成员的表达式的辅助函数：
public static class ExpressionHelper
{
public static Expression<Func<TEntity, TResult>> GetMember<TEntity, TResult>(String memberName)
{
ParameterExpression parameter = Expression.Parameter(typeof(TEntity), "p");
MemberExpression member = Expression.MakeMemberAccess(parameter, typeof(TEntity).GetMember(memberName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance).Single());
Expression<Func<TEntity, TResult>> expression = Expression.Lambda<Func<TEntity, TResult>>(member, parameter);
return (expression);
}
}
然后，我们在 DbContext.OnModelCreating 方法上调用它，作为 StructuralTypeConfiguration.Property 的参数：
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Project>().Property(ExpressionHelper.GetMember<Project, Decimal>("Budget")).IsRequired();
base.OnModelCreating(modelBuilder);
}
Is it possible to map a table column to a class field instead to a class property and how?
YOU CAN DO IT :)
Follow this link: http://weblogs.asp.net/ricardoperes/archive/2013/08/22/mapping-non-public-members-with-entity-framework-code-first.aspx
This is a common request, and really makes sense; we need to use LINQ expressions and a bit of reflection magic. First, an helper function for returning an expression that points to a member:
public static class ExpressionHelper
{
public static Expression<Func<TEntity, TResult>> GetMember<TEntity, TResult>(String memberName)
{
ParameterExpression parameter = Expression.Parameter(typeof(TEntity), "p");
MemberExpression member = Expression.MakeMemberAccess(parameter, typeof(TEntity).GetMember(memberName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance).Single());
Expression<Func<TEntity, TResult>> expression = Expression.Lambda<Func<TEntity, TResult>>(member, parameter);
return (expression);
}
}
Then, we call it on the DbContext.OnModelCreating method, as a parameter to StructuralTypeConfiguration.Property:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Project>().Property(ExpressionHelper.GetMember<Project, Decimal>("Budget")).IsRequired();
base.OnModelCreating(modelBuilder);
}
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实体框架（无论是否为 Code First）不支持映射到字段；仅限属性。
更新
正如评论中指出的，这些文档有点过时，但仍可能对任何初学者有所帮助：
为了完整起见，下面是 EF 4.1 RC 中包含的内容的链接：EF 4.1 候选版本可用
自 CTP5 以来的更改（来自上面的链接）：
Entity Framework (Code First or not) does not support mapping to a field; only to properties.
UPDATE
As pointed out in the comments, these documents are a bit dated but might still help any beginner along:
For the sake of completeness, heres a link to whats included in EF 4.1 RC: EF 4.1 Release Candidate Available
Changes since CTP5 (From the link above):