Entity Framework. Where clause with parameter from query as variable - entity-framework

Question

Task: use different where clause in one query
Here is example (it is not real query, just to illustrate the problem)
var events = ctx.Events; // ctx - EntityFramework context
var res = events
.GroupBy(ee => ee.State)
.Select(gg => new
{
State = gg.Key,
FirstTwo = events
// how to get this clause from variable
.Where(ee => ee.State == gg.Key)
.Take(2)
})
.ToList();
Next code did not work, the problem is that where expression use parameter from query gg.Key
var events = ctx.Events;
var res = events
.GroupBy(ee => ee.State)
.Select(gg => new
{
State = gg.Key,
FirstTwo = events
// 1
// how to get this clause from variable
//.Where(ee => ee.State == gg.Key)
// 2
// try to take out where expression from query
.Where(_buildExpression(gg.Key))
.Take(2)
})
.ToList();
// method
static Expression<Func<Event, bool>> _buildExpression(string state)
{
return ee => ee.State == state;
}
// exeption
An unhandled exception of type 'System.InvalidOperationException' occurred in EntityFramework.SqlServer.dll
Additional information: variable 'gg' of type 'System.Linq.IGrouping`2[System.String,Entities.Event]' referenced from scope '', but it is not defined
Example of getting where expression from variable, but does not depend on gg.Key (wrong)
Expression<Func<Event, bool>> whereClause = (ee) => (ee.State == "test");
var events = ctx.Events;
var res = events
.GroupBy(ee => ee.State)
.Select(gg => new
{
State = gg.Key,
FirstTwo = events
// 1
// how to get this clause from variable
//.Where(ee => ee.State == gg.Key)
// 2
// try to take out where expression from query
//.Where(_buildExpression(gg.Key))
// 3
// whereClause from variable, but does not depend on gg.Key
.Where(whereClause)
.Take(2)
})
.ToList();
How to take where сlause from variable with depend on gg.Key?
p.s. the query is just example of the problem. The code below does not solve the problem of real query:
var events = ctx.Events;
var res = events
.GroupBy(ee => ee.State)
.Select(gg => new
{
State = gg.Key,
FirstTwo = gg.Take(2)
})
.ToList();

Answer 1

Solution by OP.
Thanks to Ivan Stoev comment.
Expression<Func<Event, string, bool>> whereClause = (ee, state) => (ee.State == state);
var events = ctx.Events;
var res = events
.AsExpandable() // <= add this
.GroupBy(ee => ee.State)
.Select(gg => new
{
State = gg.Key,
FirstTwo = events
.Where(ee => whereClause.Invoke(ee, gg.Key)) // <= Invoke expression
.Take(2)
})
.ToList();
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