Generic repository with paging for getall method to include item count

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I am using a generic repository something like EFRepo<TEntity> which has a method

<pre>public IEmerable<TEntity> GetAll(
 Expression<Func<TEntity, bool>> filter = null,
 Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null,
 IList<Expression<Func<TEntity, object>>> includes = null,
 int? page = null,
 int? pageSize = null)
 {
        var query = context.Set<TEntity>().AsQueryable();

        if (includes != null)
        {
            query = includes.Aggregate(query, (current, include) => current.Include(include));
        }
        if (orderBy != null)
        {
            query = orderBy(query);
        }
        if (filter != null)
        {
            query = query.AsExpandable().Where(filter);
        }
        if (page != null && pageSize != null)
        {
            query = query.Skip((page.Value - 1)*pageSize.Value).Take(pageSize.Value);
        }
        return query.ToList();
 }

The problem lies here I am trying to DDD so 'TEntity' is actually entity class for EF. I need to return the total records count of the total database record as well. How shall I do it following best practises for an API?

What I have tried:

I saw PaginatedList but I don't want to use it and want to stick with the Generic my repository.

I thought of Domain class but cannot find out how will I manage with Automapper for TotalCount and other fileds mapping.

Posted 1-Jun-20 17:45pm

sam_roy

Updated 1-Jun-20 23:47pm

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Richard Deeming · Answer 1 · 2020-06-01T23:48:00

I'm not sure about "best practises" - there are many different ways to achieve the same thing, with varying degrees of complexity.

What I tend to do is return a class which encapsulates the results:

C#

public class EntityList<TEntity>
{
    public int TotalCount { get; set; }
    public int FilteredCount { get; set; }
    public IReadOnlyList<TEntity> PageData { get; set; }
}

C#

public EntityList<TEntity> GetAll(
    Expression<Func<TEntity, bool>> filter = null,
    Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null,
    IEnumerable<Expression<Func<TEntity, object>>> includes = null,
    int? page = null, int? pageSize = null)
{
    var query = context.Set<TEntity>().AsQueryable();
    if (includes != null)
    {
        query = includes.Aggregate(query, (current, include) => current.Include(include));
    }
    
    int totalCount = query.Count();
    int filteredCount = totalCount;
    
    if (filter != null)
    {
        query = query.AsExpandable().Where(filter);
        filteredCount = query.Count();
    }
    
    if (orderBy != null)
    {
        query = orderBy(query);
    }
    if (page != null && pageSize != null)
    {
        query = query.Skip((page.Value - 1) * pageSize.Value).Take(pageSize.Value);
    }
    
    var pageData = query.ToList();
    
    return new EntityList<TEntity>
    {
        TotalCount = totalCount,
        FilteredCount = filteredCount,
        PageData = pageData,
    };
}

Alternatively, OData allows you to request the total number of records to be returned in the response:
Query options overview - OData | Microsoft Docs[^]

And GraphQL takes a slightly different approach:
Pagination | GraphQL[^]