LINQ

IQueryable

This is used when you want to add and/or filter results from the database, without the query being executed already.  This is generally used with methods like ValidSamples() and FilterSamples()

The IQueryable interface inherits the IEnumerable interface so that if it represents a query, the results of that query can be enumerated.

IEnumerable

Use when you deal with in process memory object collections and loop through the collection objects.  IEnumerable uses Func objects that result in the query being executed immediately and completely, your application will see a performance boost.

Example:

using SignifyHR.Core;
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Entity;
using System.Linq;
 
namespace SignifyHR.Data.Domain
{
    public partial class exSample : IAuditable
    {
        #region Search Parameters
 
        public class SearchParameters : BaseSearchParameters
        {
            public int? SomeId { get; set; }
            public string Description { get; set; }
            public bool IsUsed { get; set; }
        }
 
        #endregion
 
        #region Eager Load Parameters
 
        public class EagerLoadParameters : BaseSearchParameters
        {
            public bool IncludeSampleDocuments { get; set; }
            public bool IncludeSampleComments { get; set; }
        }
 
        #endregion
 
        #region Protected Methods
 
        protected static IEnumerable<exSample> ValidSamples(SignifyHRDAL dbContext, EagerLoadParameters eagerLoadParms = null, SearchParameters searchParms)
        {
        	//Result not executed yet
            var samples = dbContext.exSamples.AsQueryable();
 
 			//Result not executed yet
            if (eagerLoadParms != null)
            {
                if (eagerLoadParms.IncludeSampleDocuments )
                    samples = samples.Include(item => item.exSampleDocuments);
 
                if (eagerLoadParms.IncludeSampleComments )
                    samples = samples.Include(item => item .exSampleComments);
            }
            
            //Result not executed yet
            if (searchParms!= null)
            {
                if (!String.IsNullOrWhiteSpace(searchParms.Description))
                    samples = samples.Where(item => item.Description.ToLower().Contains(searchParms.Description.ToLower()));
 
                if (searchParms.SomeId.HasValue)
                    samples = samples.Where(item => item.SomeId == searchParms.SomeId.Value);
 
                if (searchParms.IsUsed.HasValue)
                    samples = samples.Where(item => item.IsUsed == searchParms.IsUsed.Value);
            }
 
 			//Result executed immediately and completely
            return samples.AsEnumerable();
        }
    }
}

TODO: Add example for IQueryable

As many calculations, filtering should occur in IQueryable

Naming convention for IQueryable e.g. Valid{ObjectNames}