DataGrid IEnumerable vs IQueryable

Radzen.Blazor Components
1

Hi,

I followed the example in Blazor DataGrid Component with IQueryable and Line 34 "IEnumerable employees;" got my attention.

If I use this in my simple App with an EF Core backend, I find the following in the EF log:
RelationalEventId.CommandExecuted[20101] (Microsoft.EntityFrameworkCore.Database.Command)
Executed DbCommand (30ms) [Parameters=, CommandType='Text', CommandTimeout='30']
SELECT [e]....
FROM [Exports] AS [e]
INNER JOIN [Spaces] AS [s] ON [e].[SpaceId] = [s].[Id]
LEFT JOIN [Headers] AS [h] ON [e].[HeaderId] = [h].[Id]

Whereas when I change the type of the variable to IQueryable, I got this:
RelationalEventId.CommandExecuted[20101] (Microsoft.EntityFrameworkCore.Database.Command)
Executed DbCommand (4ms) [Parameters=, CommandType='Text', CommandTimeout='30']
SELECT TOP(1) [e]....
FROM [Exports] AS [e]
INNER JOIN [Spaces] AS [s] ON [e].[SpaceId] = [s].[Id]
LEFT JOIN [Headers] AS [h] ON [e].[HeaderId] = [h].[Id]

So although the underlying Object doesn't change,

                System.Linq.IQueryable<....Export> {Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.IncludableQueryable<....Export, ....Header>}
System.Collections.Generic.IEnumerable<....Export> {Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.IncludableQueryable<....Export, ....Header>}

the behaviour does.

I'm still a little confused about the why, but shouldn't the example be changed?

2

Not sure what is the question.

3

I wanted to point out that the examples may be wrong. Which cause new users (like me) to write poorly performing code and waste time debugging.

At the same time, make sure I haven't overlooked anything. And ideally an explanation why a different behavior can be observed despite the identical runtime type.

I only changed the type of the variable (in example context):
IEnumerable<Employee> employees;
to
IQueryable<Employee> employees;.

4

Ah, I see! It will be fixed immediately!