类型“ System.Dynamic.ExpandoObject”的表达式不能用于类型“ System.Linq.IQueryable”的参数

Question

I am trying to create Expression for ExpandoObject and below is my code.

var parameter = Expression.Parameter(typeof(KeyValuePair<string, object>), "k");
var left = Expression.Property(parameter, "Key");
var right = Expression.Constant(prop, typeof(string));
var equal = Expression.Equal(left, right);
var whereMethod = typeof(Queryable).GetMethods(BindingFlags.Public | BindingFlags.Static)
    .First(_ => _.Name == "Where").MakeGenericMethod(typeof(ExpandoObject));
propExp = Expression.Call(whereMethod, propExp, equal);

And I am getting Exception at Expression.Call

Expression of type 'System.Dynamic.ExpandoObject' cannot be used for parameter of type 'System.Linq.IQueryable`

Can someone please help?

Rishi

Answer 1

The expression expects System.Dynamic.ExpandoObject as the first parameter, just like the exception states:

Expression of type 'System.Dynamic.ExpandoObject' cannot be used for parameter of type 'System.Linq.IQueryable`

in this line of code you are trying to convert the where linq to an Expando object:

var whereMethod = typeof(Queryable).GetMethods(BindingFlags.Public | BindingFlags.Static)
    .First(_ => _.Name == "Where").MakeGenericMethod(typeof(ExpandoObject));

But you are failing because you have an Iqueryable object:

var whereMethod = typeof(Queryable)

adjust the code so that the whereMethod variable be a dynamic expando object and it will work.