Add GroupBy and Select implementation in Specification<T> Pattern.

[TanvirArjel]

There is no implantation details for the GroupBy and Select in Specification pattern. Please add this showing how we can get the data based on GroupBy using the Specification pattern.

For example how can I build the following equivalent output uisng Specification pattern:

    var empAvgSalary =  _context.Set<Employee>().GroupBy(e => new {e.EmployeeName, e.DepartmentName})
            .Select(group => new
            {
                EmployeeName = group.Key.EmployeeName,
                DepartmentName = group.Key.DepartmentName,
                AvgSalary = group.Average(e => e.Salary)
            }).ToList();

Thank you.

[efleming18]

Hey @TanvirArjel - Implementing those would be useful I agree. We may switch to using this NuGet package created by @ardalis (a maintainer on this repo) for the functionality. Before we do that though, here are some links to hopefully help with your questions.

Specifications Repo

GroupBy Implementation

GroupBy Tests

Selector Implementation

Selector Tests

Hopefully this helps for now!

[efleming18]

I'm going to close this issue as the repo has been updated to use the Ardalis.Specifications NuGet packages linked in the comments above.

[jamsshhayd]

Anybody found solution to this? I am trying to add a group by, in Query but it seems there is no method available. Plus, I can pass on an expression in PostProcessingAction but I do not want my query to be processed on a List.

[fiseni]

There is no support for GroupBy for now. Refer to this issue here.