linq 查询：列表作为输入参数

发布于 2024-10-29 05:35:10 字数 546 浏览 1 评论 0原文

假设我们有 2 个对象模型：

class MyModel1{
   int ModelID {get;set;}
   string Var2 {get;set;}
}

class MyModel2{
   int ModelID {get;set;}
   string Var2 {get;set;}
}

假设我们有一个 linq to sql 查询，它返回 MyModel1 的列表，如下所示：

var OutputModel1 = from t in MyDataContext
            where...
            select new MyModel1
            {...}.ToList();

Return OutputModel1 as List<MyModel1>;

现在我有了这个列表，我想将此列表传递给另一个查询，该查询将返回ModelID 相同的 MyModel2 的列表。

如果您对如何执行此操作有任何建议，请告诉我。

谢谢。

原文

Let's say we have 2 object models:

class MyModel1{
   int ModelID {get;set;}
   string Var2 {get;set;}
}

class MyModel2{
   int ModelID {get;set;}
   string Var2 {get;set;}
}

Let's say that we have a linq to sql query that returns a list of MyModel1 like this:

var OutputModel1 = from t in MyDataContext
            where...
            select new MyModel1
            {...}.ToList();

Return OutputModel1 as List<MyModel1>;

Now that I have this list, I'd like to pass this list to another query that'll return a list of of MyModel2 where the ModelID is the same.

Let me know if you have some suggestions on how to do this.

Thanks.

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一瞬间的火花 2024-11-05 05:35:10

如果您只是想稍后为每个 MyModel1 创建一个 MyModel2 副本，那么很简单：

var OutputModel2 = OutputModel1.Select(m =>
    new MyModel2 { 
        ModelId = m.ModelId,
        Var2 = m.Var2,
    }).ToList();

如果您需要查询具有相同 id 的那些 MyModel2 对象的数据上下文作为 MyModel1 对象（即存在关系），那么它是不同的（但您应该提供该信息）。

PS：不需要写成List——ToList的返回值就是一个List，不再需要了，不少于。

If you simply want to make a MyModel2 copy of each MyModel1 some point afterwards, then it's simple:

var OutputModel2 = OutputModel1.Select(m =>
    new MyModel2 { 
        ModelId = m.ModelId,
        Var2 = m.Var2,
    }).ToList();

If you need to query the data context for those MyModel2 objects with the same ids as the MyModel1 objects (i.e., there is a relation), then it's different (but you should provide that information).

PS: There's no need to write as List<MyModel1> -- the return value of ToList is exactly a List<MyModel1>, no more, no less.

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掐死时间 2024-11-05 05:35:10

var OutputModel2 = (from m in MyDataContext.Model2Collection where MyDataContext.Model1Collection.Any(x => x.ModelID == m.ModelID && x.Var2 == 3/*PUT YOUR WHERE CLAUSE HERE*/)).ToList();

var OutputModel2 = (from m in MyDataContext.Model2Collection where MyDataContext.Model1Collection.Any(x => x.ModelID == m.ModelID && x.Var2 == 3/*PUT YOUR WHERE CLAUSE HERE*/)).ToList();

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你是暖光i 2024-11-05 05:35:10

假设您正在寻找现有 Model2 的子集，您可以使用如下所示的内容：

var OutputModel2 = from t2 in CollectionOfModel2s
                           join t1 in OutputModel1 on t2.ModelID equals t1.ModelID
                           select t2;

“join”函数类似于 SQL 中的内部联接，并且不会返回任何不匹配的 t2。

有关于连接和其他内容的相当详细的描述：
http://msdn.microsoft.com/en-us/library/bb397941 .aspx#Y275

Assuming that you're looking for a subset of existing Model2's, you could use something like the following:

var OutputModel2 = from t2 in CollectionOfModel2s
                           join t1 in OutputModel1 on t2.ModelID equals t1.ModelID
                           select t2;

The "join" functions like an inner join in SQL, and won't return any t2's that don't have a match.

There's a fairly detailed description of joins and whatnot at:
http://msdn.microsoft.com/en-us/library/bb397941.aspx#Y275

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