I am new to Entity Framework and I keep getting the EntityCommandCompilationException specified method not supported in Entity Framework. I can't figure out why this exception is being raised.
I have created a custom UDF aggregate function my_Func() for my installation of MySQL server 5.7 using the guidelines posted here. It works just like any ordinary aggregate function e.g. Sum() would work. i.e. I can execute the statement select my_Func(Column4) from db.table and it returns the desired result as a double. I have tested it and it works in MySQL server. I want to be able to use this method in a linq to entities query and in order to do this I have done the following.
using (var context = new dbEntities())
{
var results = from items in context.table
group items by new
{ items.Column1, items.Column2 } into groupingItem
select new OutputType()
{
GroupedResult = groupingItem.OrderBy(x => x.Column3).Select(x => x.Column4).my_Func()
};
}
I created a static class which contains the method.
public static class ModelDefinedFunctions
{
[DbFunction("dbModel.Store", "my_Func")]
public static double my_Func(this IEnumerable<double> items)
{
throw new NotSupportedException("Direct calls are not supported.");
}
}
in the .edmx file I have added the following tag manually
<Function Name="my_Func" ReturnType="double" Aggregate="true"
BuiltIn="false" NiladicFunction="false"
IsComposable="true" ParameterTypeSemantics="AllowImplicitConversion" Schema="db">
<Parameter Name="value" Type="Collection(double)" Mode="In" />
</Function>