temp commit, adding expression builder to filtering, not finished

mesoft.gridview/Models/GridViewModelProvider.cs

@@ -1,9 +1,11 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Linq.Expressions;
 using System.Web;
 using System.Web.Helpers;
 
+
 namespace mesoft.gridview.Models
 {
     public class GridViewModelProvider
@@ -46,17 +48,26 @@ private static IQueryable<Customer> GetResources(IQueryable<Customer> Customers,
             //filter
             if (PagingData.Filters != null)
             {
+                var predicate = PredicateBuilder.True<Customer>();
+
+
                 foreach (var filterObj in PagingData.Filters)
                 {
-                    switch (filterObj.Column)
-                    {
-                        case "City":
-                            if (filterObj.Value.ToLower() != "all")                               
-                                customers = customers.Where(x => x.City == filterObj.Value);
-                            break;
+                    var tempValue = filterObj.Value;
+                    var tempColumn = filterObj.Column;
+                    var tempConj = filterObj.Conjunction;
+                    var tempOpr = filterObj.Operator;
 
-                    }
+                    predicate = predicate.
 
+                    //switch (filterObj.Column)
+                    //{
+                    //    case "City":
+                    //        if (filterObj.Value.ToLower() != "all")
+                    //            customers = customers.Where(x => x.City == tempValue);
+
+                    //        break;
+                    //}
                 }
             }
 

mesoft.gridview/Models/UniversalPredicateBuilder.cs

@@ -0,0 +1,103 @@
+/**********************************************/
+/*By: Pete Montgomery
+ * https://petemontgomery.wordpress.com/2011/02/10/a-universal-predicatebuilder/
+/**********************************************/
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Web;
+
+namespace mesoft.gridview.Models
+{
+    /// <summary>
+    /// Enables the efficient, dynamic composition of query predicates.
+    /// </summary>
+    public static class PredicateBuilder
+    {
+        /// <summary>
+        /// Creates a predicate that evaluates to true.
+        /// </summary>
+        public static Expression<Func<T, bool>> True<T>() { return param => true; }
+
+        /// <summary>
+        /// Creates a predicate that evaluates to false.
+        /// </summary>
+        public static Expression<Func<T, bool>> False<T>() { return param => false; }
+
+        /// <summary>
+        /// Creates a predicate expression from the specified lambda expression.
+        /// </summary>
+        public static Expression<Func<T, bool>> Create<T>(Expression<Func<T, bool>> predicate) { return predicate; }
+
+        /// <summary>
+        /// Combines the first predicate with the second using the logical "and".
+        /// </summary>
+        public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> first, Expression<Func<T, bool>> second)
+        {
+            return first.Compose(second, Expression.AndAlso);
+        }
+
+        /// <summary>
+        /// Combines the first predicate with the second using the logical "or".
+        /// </summary>
+        public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> first, Expression<Func<T, bool>> second)
+        {
+            return first.Compose(second, Expression.OrElse);
+        }
+
+        /// <summary>
+        /// Negates the predicate.
+        /// </summary>
+        public static Expression<Func<T, bool>> Not<T>(this Expression<Func<T, bool>> expression)
+        {
+            var negated = Expression.Not(expression.Body);
+            return Expression.Lambda<Func<T, bool>>(negated, expression.Parameters);
+        }
+
+        /// <summary>
+        /// Combines the first expression with the second using the specified merge function.
+        /// </summary>
+        static Expression<T> Compose<T>(this Expression<T> first, Expression<T> second, Func<Expression, Expression, Expression> merge)
+        {
+            // zip parameters (map from parameters of second to parameters of first)
+            var map = first.Parameters
+                .Select((f, i) => new { f, s = second.Parameters[i] })
+                .ToDictionary(p => p.s, p => p.f);
+
+            // replace parameters in the second lambda expression with the parameters in the first
+            var secondBody = ParameterRebinder.ReplaceParameters(map, second.Body);
+
+            // create a merged lambda expression with parameters from the first expression
+            return Expression.Lambda<T>(merge(first.Body, secondBody), first.Parameters);
+        }
+
+        class ParameterRebinder : ExpressionVisitor
+        {
+            readonly Dictionary<ParameterExpression, ParameterExpression> map;
+
+            ParameterRebinder(Dictionary<ParameterExpression, ParameterExpression> map)
+            {
+                this.map = map ?? new Dictionary<ParameterExpression, ParameterExpression>();
+            }
+
+            public static Expression ReplaceParameters(Dictionary<ParameterExpression, ParameterExpression> map, Expression exp)
+            {
+                return new ParameterRebinder(map).Visit(exp);
+            }
+
+            protected override Expression VisitParameter(ParameterExpression p)
+            {
+                ParameterExpression replacement;
+
+                if (map.TryGetValue(p, out replacement))
+                {
+                    p = replacement;
+                }
+
+                return base.VisitParameter(p);
+            }
+        }
+    }
+}

mesoft.gridview/mesoft.gridview.csproj

@@ -132,6 +132,7 @@
     <Compile Include="Models\GridviewModel.cs" />
     <Compile Include="Models\GridViewModelProvider.cs" />
     <Compile Include="Models\MyDbContext.cs" />
+    <Compile Include="Models\UniversalPredicateBuilder.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>