EFPlus.cs

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Data.Entity.Core.Metadata.Edm;
using System.Data.Entity.Infrastructure;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Z.BulkOperations;

namespace DiamondERP.Helpers
{
    public static class ExtEFPlusWhere
    {
        public static IQueryable<AuditEntries> Where<T>(this DbSet<AuditEntries> set, T entry) where T : class
        {
            var context = set.GetContext();
            var keyNames = context.GetKeyNames<T>();

            if (entry == null)
            {
                return set.Where(x => false);
            }

            var query = set.Where(x => x.EntityTypeName == typeof(T).Name);

            foreach (var keyName in keyNames)
            {
                var property = entry.GetType().GetProperty(keyName);
                var value = property.GetValue(entry, null).ToString();

                query = query.Where(x => x.AuditEntryProperties.Any(y => y.PropertyName == property.Name && y.NewValue == value));
            }

            query = query.Include(x => x.AuditEntryProperties).OrderBy(x => x.CreatedDate);

            return query;
        }

        public static List<AuditEntries> Where<T>(this DbSet<AuditEntries> set, params object[] keyValues) where T : class
        {
            var context = set.GetContext();
            var keyNames = context.GetKeyNames<T>();

            var query = set.Where(x => x.EntityTypeName == typeof(T).Name);

            if (keyValues == null)
            {
                throw new Exception("Audit_Key_Null");
            }
            if (keyValues.Length != keyNames.Length)
            {
                throw new Exception("Audit_Key_OutOfBound");
            }

            for (var i = 0; i < keyNames.Length; i++)
            {
                var propertyName = keyNames[i].ToString();
                var value = keyValues[i] != null ? keyValues[i].ToString() : "";

                query = query.Where(x => x.AuditEntryProperties.Any(y => y.PropertyName == propertyName && y.NewValue == value));
            }

            query = query.Include(x => x.AuditEntryProperties).OrderBy(x => x.CreatedDate).Take(5);
            var lst = query.ToList();
            
            return lst;
        }
        public static string[] GetKeyNames<TEntity>(this DbContext context)
            where TEntity : class
        {
            return context.GetKeyNames(typeof(TEntity));
        }

        public static string[] GetKeyNames(this DbContext context, Type entityType)
        {
            var metadata = ((IObjectContextAdapter)context).ObjectContext.MetadataWorkspace;

            // Get the mapping between CLR types and metadata OSpace
            var objectItemCollection = ((ObjectItemCollection)metadata.GetItemCollection(DataSpace.OSpace));

            // Get metadata for given CLR type
            var entityMetadata = metadata
                    .GetItems<EntityType>(DataSpace.OSpace)
                    .Single(e => objectItemCollection.GetClrType(e) == entityType);

            return entityMetadata.KeyProperties.Select(p => p.Name).ToArray();
        }
    }
}