c# - Linq to Entities 中的 Union 错误

Question

我在要合并 2 个列表的查询中遇到问题。

我想将表 Places 和 Locations 中的记录合并到 View 模型属性 Places 中。

Fruits = (from e in db.Fruits
           where !e.Excluded
           select new FruitViewModel()
           {
               CodFood = e.CodFood,
               Name = e.Name,
               Color = e.Color,
               Places = (from p in e.Places
                          where !p.Excluded
                          select new FruitViewModel()
                          {
                              CodPlace = p.CodPlace,
                              Name = p.Name
                          }).Union(
                          from r in e.Locations
                          where !r.Excluido
                          select new FruitViewModel()
                          {
                              CodLocation = r.CodLocation,
                              Name = p.Name
                          })
           }),

但它给了我:

System.NotSupportedException: The type 'Project.ViewModel.Fruits.FruitsViewModel' appears in two structurally incompatible initializations within a single LINQ to Entities query. A type can be initialized in two places in the same query, but only if the same properties are set in both places and those properties are set in the same order.

我可以在 Linq 执行后合并为 this answer ，但我想保持简单，不要过多更改此代码，如果可能的话 - 在延迟执行之前进行查询。

我该如何解决？

Answer 1

根据错误消息，您的 FruitViewModel 初始化似乎有问题。试试这个:

           Places = (from p in e.Places
                      where !p.Excluded
                      select new FruitViewModel()
                      {
                          CodLocation = "",
                          CodPlace = p.CodPlace,
                          Name = p.Name
                      }).Union(
                      from r in e.Locations
                      where !r.Excluido
                      select new FruitViewModel()
                      {
                          CodLocation = r.CodLocation,
                          CodPlace = "",
                          Name = p.Name
                      })