blocks|key|1849705|text|我不确定Silverligth，但在linq+to+objects中，我总是使用any()进行这些查询。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1849706|var+q+=+from+t+in+svc.OpenTranaction
++++++++where+txnIds.Any(t.OpenTransactionId)
++++++++select+t;|code-block|syntax|javascript|1849707|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I'm not sure about Silverligth, but in linq to objects i always use any() for these queries.

<pre><code>var q = from t in svc.OpenTranaction
 where txnIds.Any(t.OpenTransactionId)
 select t;
</code></pre>

blocks|key|2063859|text|来自MSDN|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2063860|static+Expression<Func<TElement,+bool>>+BuildContainsExpression<TElement,+TValue>(
++++Expression<Func<TElement,+TValue>>+valueSelector,+IEnumerable<TValue>+values)
{
++++if+(null+==+valueSelector)+{+throw+new+ArgumentNullException("valueSelector");+}
++++if+(null+==+values)+{+throw+new+ArgumentNullException("values");+}
++++ParameterExpression+p+=+valueSelector.Parameters.Single();

++++//+p+=>+valueSelector(p)+==+values[0]+%7C%7C+valueSelector(p)+==+...
++++if+(!values.Any())
++++{
++++++++return+e+=>+false;
++++}

++++var+equals+=+values.Select(
+++++++++++++value+=>+(Expression)Expression.Equal(valueSelector.Body,+Expression.Constant(value,+typeof(TValue))));

++++var+body+=+equals.Aggregate<Expression>((accumulate,+equal)+=>+Expression.Or(accumulate,+equal));

++++return+Expression.Lambda<Func<TElement,+bool>>(body,+p);
}+|code-block|syntax|javascript|2063861|然后查询变成：|2063862|var+query2+=+context.Entities.Where(BuildContainsExpression<Entity,+int>(e+=>+e.ID,+ids));|2063863|entityMap|0|LINK|mutability|MUTABLE|url|http://social.msdn.microsoft.com/forums/en-US/adodotnetentityframework/thread/095745fe-dcf0-4142-b684-b7e4a1ab59f0/^0|2|4|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

From <a href="http://social.msdn.microsoft.com/forums/en-US/adodotnetentityframework/thread/095745fe-dcf0-4142-b684-b7e4a1ab59f0/" rel="noreferrer">MSDN</a>:

<pre><code>static Expression&lt;Func&lt;TElement, bool&gt;&gt; BuildContainsExpression&lt;TElement, TValue&gt;(
 Expression&lt;Func&lt;TElement, TValue&gt;&gt; valueSelector, IEnumerable&lt;TValue&gt; values)
{
 if (null == valueSelector) { throw new ArgumentNullException("valueSelector"); }
 if (null == values) { throw new ArgumentNullException("values"); }
 ParameterExpression p = valueSelector.Parameters.Single();

 // p =&gt; valueSelector(p) == values[0] || valueSelector(p) == ...
 if (!values.Any())
 {
 return e =&gt; false;
 }

 var equals = values.Select(
 value =&gt; (Expression)Expression.Equal(valueSelector.Body, Expression.Constant(value, typeof(TValue))));

 var body = equals.Aggregate&lt;Expression&gt;((accumulate, equal) =&gt; Expression.Or(accumulate, equal));

 return Expression.Lambda&lt;Func&lt;TElement, bool&gt;&gt;(body, p);
} 
</code></pre>

and the query becomes:

<pre><code>var query2 = context.Entities.Where(BuildContainsExpression&lt;Entity, int&gt;(e =&gt; e.ID, ids));
</code></pre>

blocks|key|1849923|text|下面的示例演示了如何使用DataServiceContext：http://blogs.msdn.com/phaniraj/archive/2008/07/17/set-based-operations-in-ado-net-data-services.aspx编写基于集合的查询|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1849924|entityMap|0|LINK|mutability|MUTABLE|url|http://blogs.msdn.com/phaniraj/archive/2008/07/17/set-based-operations-in-ado-net-data-services.aspx^0|V|2S|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Here's an example where I demonstrate how to write set-based queries using the DataServiceContext :
<a href="http://blogs.msdn.com/phaniraj/archive/2008/07/17/set-based-operations-in-ado-net-data-services.aspx" rel="nofollow noreferrer">http://blogs.msdn.com/phaniraj/archive/2008/07/17/set-based-operations-in-ado-net-data-services.aspx</a>

blocks|key|1849956|text|您可以回到手头编写一些e-sql+(请注意关键字"it")：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1849957|return+CurrentDataSource.Product.Where("it.ID+IN+{4,5,6}");+|code-block|syntax|javascript|1849958|下面是我用来从集合YMMV生成一些e-sql的代码：|1849959|string[]+ids+=+orders.Select(x=>x.ProductID.ToString()).ToArray();
return+CurrentDataSource.Products.Where("it.ID+IN+{"+%2B+string.Join(",",+ids)+%2B+"}");|1849960|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

You can fall back on hand coding some e-sql (note the keyword "it"):

<pre><code>return CurrentDataSource.Product.Where("it.ID IN {4,5,6}"); 
</code></pre>

Here is the code that I used to generate some e-sql from a collection, YMMV:

<pre><code>string[] ids = orders.Select(x=&gt;x.ProductID.ToString()).ToArray();
return CurrentDataSource.Products.Where("it.ID IN {" + string.Join(",", ids) + "}");
</code></pre>

blocks|key|2064050|text|非常感谢。对我来说，WhereIn扩展方法就足够了。我对其进行了分析，并为DataBase生成了与e-sql相同的SQL命令。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2064051|public+Estado[]+GetSomeOtherMore(int[]+values)
{
++++var+result+=+_context.Estados.WhereIn(args+=>+args.Id,+values)+;
++++return+result.ToArray();
}|code-block|syntax|javascript|2064052|生成了以下内容：|2064053|SELECT+
[Extent1].[intIdFRLEstado]+AS+[intIdFRLEstado],+
[Extent1].[varDescripcion]+AS+[varDescripcion]
FROM+[dbo].[PVN_FRLEstados]+AS+[Extent1]
WHERE+(2+=+[Extent1].[intIdFRLEstado])+OR+(4+=+[Extent1].[intIdFRLEstado])+OR+(8+=+[Extent1].[intIdFRLEstado])|2064054|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Thanks very much. WhereIn extension method was enough for me. I profiled it and generated the same SQL command to the DataBase as e-sql.

<pre><code>public Estado[] GetSomeOtherMore(int[] values)
{
 var result = _context.Estados.WhereIn(args =&gt; args.Id, values) ;
 return result.ToArray();
}
</code></pre>

Generated this:

<pre><code>SELECT 
[Extent1].[intIdFRLEstado] AS [intIdFRLEstado], 
[Extent1].[varDescripcion] AS [varDescripcion]
FROM [dbo].[PVN_FRLEstados] AS [Extent1]
WHERE (2 = [Extent1].[intIdFRLEstado]) OR (4 = [Extent1].[intIdFRLEstado]) OR (8 = [Extent1].[intIdFRLEstado])
</code></pre>

blocks|key|1850071|text|我认为在LINQ中加入可以是一种漫步。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1850072|不过，我还没有测试代码。希望能有所帮助。干杯。:-)|1850073|List<long?>+txnIds+=+new+List<long?>();
//+Fill+list+

var+q+=+from+t+in+svc.OpenTransaction
++++++++join+tID+in+txtIds+on+t+equals+tID
++++++++select+t;|code-block|syntax|javascript|1850074|加入LINQ：|1850075|http://weblogs.asp.net/salimfayad/archive/2008/07/09/linq-to-entities-join-queries.aspx|offset|length|1850076|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|0|0|2F|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|W|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|X|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|Y|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|Z|8|@]|9|@$M|10|N|11|1|12]]|A|$]]|$1|O|3|-4|5|6|7|13|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|L]]]]

I think a Join in LINQ can be a walkaround.

I haven't tested the code though. Hope it helps. Cheers. :-)

<pre><code>List&lt;long?&gt; txnIds = new List&lt;long?&gt;();
// Fill list 

var q = from t in svc.OpenTransaction
 join tID in txtIds on t equals tID
 select t;
</code></pre>

Join in LINQ:

<a href="http://weblogs.asp.net/salimfayad/archive/2008/07/09/linq-to-entities-join-queries.aspx" rel="nofollow noreferrer">http://weblogs.asp.net/salimfayad/archive/2008/07/09/linq-to-entities-join-queries.aspx</a>

blocks|key|1850103|text|为了完成记录，下面是我最后使用的代码(为了清楚起见，省略了错误检查)……|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1850104|//+How+the+function+is+called
var+q+=+(from+t+in+svc.OpenTransaction.Expand("Currency,LineItem")
+++++++++select+t)
+++++++++.Where(BuildContainsExpression<OpenTransaction,+long>(tt+=>+tt.OpenTransactionId,+txnIds));



+//+The+function+to+build+the+contains+expression
+++static+System.Linq.Expressions.Expression<Func<TElement,+bool>>+BuildContainsExpression<TElement,+TValue>(
++++++++++++++++System.Linq.Expressions.Expression<Func<TElement,+TValue>>+valueSelector,+
++++++++++++++++IEnumerable<TValue>+values)
++++++++{
++++++++++++if+(null+==+valueSelector)+{+throw+new+ArgumentNullException("valueSelector");+}
++++++++++++if+(null+==+values)+{+throw+new+ArgumentNullException("values");+}
++++++++++++System.Linq.Expressions.ParameterExpression+p+=+valueSelector.Parameters.Single();

++++++++++++//+p+=>+valueSelector(p)+==+values[0]+%7C%7C+valueSelector(p)+==+...
++++++++++++if+(!values.Any())
++++++++++++{
++++++++++++++++return+e+=>+false;
++++++++++++}

++++++++++++var+equals+=+values.Select(value+=>+(System.Linq.Expressions.Expression)System.Linq.Expressions.Expression.Equal(valueSelector.Body,+System.Linq.Expressions.Expression.Constant(value,+typeof(TValue))));
++++++++++++var+body+=+equals.Aggregate<System.Linq.Expressions.Expression>((accumulate,+equal)+=>+System.Linq.Expressions.Expression.Or(accumulate,+equal));
++++++++++++return+System.Linq.Expressions.Expression.Lambda<Func<TElement,+bool>>(body,+p);
++++++++}|code-block|syntax|javascript|1850105|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

To complete the record, here's the code I finally used (error checking omitted for clarity)...

<pre><code>// How the function is called
var q = (from t in svc.OpenTransaction.Expand("Currency,LineItem")
 select t)
 .Where(BuildContainsExpression&lt;OpenTransaction, long&gt;(tt =&gt; tt.OpenTransactionId, txnIds));



 // The function to build the contains expression
 static System.Linq.Expressions.Expression&lt;Func&lt;TElement, bool&gt;&gt; BuildContainsExpression&lt;TElement, TValue&gt;(
 System.Linq.Expressions.Expression&lt;Func&lt;TElement, TValue&gt;&gt; valueSelector, 
 IEnumerable&lt;TValue&gt; values)
 {
 if (null == valueSelector) { throw new ArgumentNullException("valueSelector"); }
 if (null == values) { throw new ArgumentNullException("values"); }
 System.Linq.Expressions.ParameterExpression p = valueSelector.Parameters.Single();

 // p =&gt; valueSelector(p) == values[0] || valueSelector(p) == ...
 if (!values.Any())
 {
 return e =&gt; false;
 }

 var equals = values.Select(value =&gt; (System.Linq.Expressions.Expression)System.Linq.Expressions.Expression.Equal(valueSelector.Body, System.Linq.Expressions.Expression.Constant(value, typeof(TValue))));
 var body = equals.Aggregate&lt;System.Linq.Expressions.Expression&gt;((accumulate, equal) =&gt; System.Linq.Expressions.Expression.Or(accumulate, equal));
 return System.Linq.Expressions.Expression.Lambda&lt;Func&lt;TElement, bool&gt;&gt;(body, p);
 }
</code></pre>

blocks|key|2064212|text|对不起，新用户，我本想对实际的答案进行评论，但似乎我还不能这样做？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2064213|无论如何，关于BuildContainsExpression()的示例代码的答案，请注意，如果您在数据库实体(即非内存对象)上使用该方法，并且您使用的是IQueryable，那么它实际上必须转到数据库，因为它基本上执行了大量的SQL“或”条件来检查"where+in“子句(使用SQL+Profiler运行它来查看)。|2064214|这可能意味着，如果您正在使用多个BuildContainsExpression()来提炼一个IQueryable，那么它不会像您预期的那样将其转换为一条在最后运行的BuildContainsExpression语句。|2064215|我们的解决方法是使用多个LINQ+joins将其保持在一个SQL调用中。|2064216|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

Sorry new user, I would have commented on the actual answer, but it seems I can't do that yet?

Anyway, in regards to the answer with sample code for BuildContainsExpression(), be aware that if you use that method on database Entities (i.e. not in-memory objects) and you are using IQueryable, that it actually has to go off to the database since it basically does a lot of SQL "or" conditions to check the "where in" clause (run it with SQL Profiler to see).

This can mean, if you are refining an IQueryable with multiple BuildContainsExpression(), it won't turn it in to one SQL statement that gets run at the end as you expect.

The workaround for us was to use multiple LINQ joins to keep it to one SQL call.

blocks|key|1850258|text|除了所选答案之外。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1850259|将Expression.Or替换为Expression.OrElse以配合Nhibernate使用，并修复Unable+to+cast+object+of+type+'NHibernate.Hql.Ast.HqlBitwiseOr'+to+type++'NHibernate.Hql.Ast.HqlBooleanExpression'异常。|offset|length|style|CODE|1850260|entityMap^0|0|1|D|H|H|1H|36|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]|$D|N|E|O|F|G]|$D|P|E|Q|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|R|8|@]|9|@]|A|$]]]|I|$]]

In addition to selected answer. 

Replace <code>Expression.Or</code> with <code>Expression.OrElse</code> to use with Nhibernate and fix <code>Unable to cast object of type 'NHibernate.Hql.Ast.HqlBitwiseOr' to type 
'NHibernate.Hql.Ast.HqlBooleanExpression'</code> exception.

I'm trying to create a query which uses a list of ids in the where clause, using the Silverlight ADO.Net Data Services client api (and therefore Linq To Entities). Does anyone know of a workaround to Contains not being supported?

I want to do something like this:

<pre><code>List&lt;long?&gt; txnIds = new List&lt;long?&gt;();
// Fill list 

var q = from t in svc.OpenTransaction
 where txnIds.Contains(t.OpenTransactionId)
 select t;
</code></pre>

<hr>

Tried this:

<pre><code>var q = from t in svc.OpenTransaction
where txnIds.Any&lt;long&gt;(tt =&gt; tt == t.OpenTransactionId)
select t;
</code></pre>

But got "The method 'Any' is not supported".

'Contains()' workaround using Linq to Entities?

数据库

我正在尝试创建一个查询，它使用where子句中的I列表，使用Silverlight ADO.Net数据服务客户端api (因此也是Linq to Entities)。有没有人知道包含不受支持的解决方法？我想做这样的事情：List<long?> txnIds = new List<long?>();// Fill lis...

问使用Linq to Entities的“‘Contains()”解决方法？
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