在实体框架更新方法中无法将bool值设置为false

问题描述

当我尝试更新现有实体时遇到一个奇怪的问题.

I got strange problem when I try to update existing entity.

public void Update(VisitDTO item)
        {
            using (var ctx = new ReceptionDbContext())
            {
                var entityToUpdate = ctx.Visits.Attach(new Visit { Id = item.Id });
                var updatedEntity = Mapper.Map<Visit>(item);
                ctx.Entry(entityToUpdate).CurrentValues.SetValues(updatedEntity);
                ctx.SaveChanges();

            }

这是我的更新方法.在enity Visit中，我得到了一些bool值，但是我无法将它们设置为false，当从false更新为true时还可以，但是当我需要从true更改为false时，实体不会更新这些bool值，其他属性也会正确更新

This is my update method.In enity Visit I got some bools values, but i cannot set these to false , when it comes to update from false to true its okay but when I need to change from true to false entity does not update these bools values, other properties updating correctly.

推荐答案

问题是default(bool)== false.

The problem is that default(bool) == false.

 var entityToUpdate = ctx.Visits.Attach(new Visit { Id = item.Id });

与

 var entityToUpdate = ctx.Visits.Attach(new Visit
 {
     Id = item.Id,
     AnyBool = false        // default(bool)
 });

附加集所有字段都变为UNCHANGED状态.

Attach sets all fields to the UNCHANGED state.

EntityFramework假定新的Visit对象包含正确的值(即使不是).将EF更新为false会被忽略，因为EF认为它已经为假！

EntityFramework assumes that the new Visit object contains the correct values (even though it does not). Updating AnyBool to false is ignored, because EF thinks it already is false!

对于需要修改的字段，您需要手动将状态更改为已修改":

You need to manually change the status to MODIFIED for fields which are to be modified:

ctx.Entry(entityToUpdate).State = EntityState.Modified;                 // all fields
ctx.Entry(entityToUpdate).Property(x => x.AnyBool).IsModified = true;   // one field

请参见如何仅更新实体框架中的一个字段?

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