new filter type added and iplemented expression feature to collections

README.md

@@ -166,6 +166,41 @@ Okay, now select users only who have sport cars capable of speeds up to 300 km /
    }
 }
 ```
+If we want to complicate the situation a little more, we can select users only who have more than 4 sport cars capable of speeds up to 300 km / hour with model Mercedes.
+
+
+```csharp
+var filter = new FilterContainer
+    {
+	Where = new TreeFilter
+	{
+        Field = "Cars",
+        FilterType = WhereFilterType.CountGreaterThan,
+	    Value = 4,
+	    OperandsOfCollections = new TreeFilter
+	    {
+		    OperatorType = TreeFilterType.And,
+		    Operands = new List<TreeFilter>
+		    {
+		     new TreeFilter
+		    	{
+			    Field = "MaxSpeed",
+			    FilterType = WhereFilterType.GreaterThan,
+			    Value = 300
+		    	},
+			    new TreeFilter
+			    {
+			    Field = "Model",
+			    FilterType = WhereFilterType.Equals,
+			    Value = "Mercedes"
+		    	}
+		    }
+
+	    }
+	},
+    };
+```
+
 Field supports the appeal to the properties of the members of the entity with unlimited nesting. Similarly works sorting.
 
 ## Filtering methods
@@ -185,6 +220,11 @@ Currently FilterType allows you to filter by the following ways:
 2. Applied to the listed items without using Value:
   * Any
   * NotAny
+  * CountEquals
+  * CountLessThan
+  * CountGreaterThan
+  * CountLessThanOrEqual
+  * CountGreaterThanOrEqual
 
 ## Entity members
 Available types for single member entities, **which can be filtered**:

src/QueryDesignerCore/Expressions/WhereExpression.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Expressions;
 using System.Reflection;
@@ -15,6 +16,12 @@ internal static class WhereExpression
         /// </summary>
         private static readonly Type StringType = typeof(string);
 
+
+        /// <summary>
+        /// Integer type.
+        /// </summary>
+        private static readonly Type IntType = typeof(int);
+
         /// <summary>
         /// Expression type.
         /// </summary>
@@ -71,11 +78,45 @@ internal static class WhereExpression
                 method => method.Name == "Any" && method.IsStatic &&
                 method.GetParameters().Length == 2);
 
+        /// <summary>
+        /// Info about "Any" method with one parameter for collection.
+        /// </summary>
+        private static readonly MethodInfo CollectionCount = QueryableType.GetRuntimeMethods().Single(
+                method => method.Name == "Count" &&
+                method.GetParameters().Length == 1);
+
+        /// <summary>
+        /// Info about "Any" method with one parameter for collection.
+        /// </summary>
+        private static readonly MethodInfo CollectionCount2 = QueryableType.GetRuntimeMethods().Single(
+                method => method.Name == "Count" &&
+                method.GetParameters().Length == 2);
+
         /// <summary>
         /// Info about method of constructing expressions.
         /// </summary>
         private static readonly MethodInfo ExpressionMethod = typeof(WhereExpression).GetRuntimeMethods().FirstOrDefault(m => m.Name == "GetExpression");
 
+        /// <summary>
+        /// Info about method of constructing expressions.
+        /// </summary>
+        private static readonly MethodInfo ExpressionTreeMethod = typeof(WhereExpression).GetRuntimeMethods().FirstOrDefault(m => m.Name == "GetTreeExpression");
+
+
+        /// <summary>
+        /// Info about avaliable methods for filter types.
+        /// </summary>
+        private static readonly Dictionary<WhereFilterType, List<MethodInfo>> FilterTypeAvaliableMethods = new Dictionary<WhereFilterType, List<MethodInfo>>()
+        {
+            {WhereFilterType.Any, new List<MethodInfo>(){CollectionAny,CollectionAny2 } },
+            {WhereFilterType.NotAny, new List<MethodInfo>(){CollectionAny,CollectionAny2 } },
+            {WhereFilterType.CountEquals, new List<MethodInfo>(){ CollectionCount, CollectionCount2 } },
+            {WhereFilterType.CountGreaterThan, new List<MethodInfo>(){ CollectionCount, CollectionCount2 } },
+            {WhereFilterType.CountGreaterThanOrEqual, new List<MethodInfo>(){ CollectionCount, CollectionCount2 } },
+            {WhereFilterType.CountLessThan, new List<MethodInfo>(){ CollectionCount, CollectionCount2 } },
+            {WhereFilterType.CountLessThanOrEqual, new List<MethodInfo>(){ CollectionCount, CollectionCount2 } },
+        };
+
         /// <summary>
         /// Available types for conversion.
         /// </summary>
@@ -126,6 +167,8 @@ internal static class WhereExpression
         public static Expression<Func<T, bool>> GetExpression<T>(this WhereFilter filter, string suffix = "")
         {
             var e = Expression.Parameter(typeof(T), "e" + suffix);
+
+
             var exs = GetExpressionForField(e, filter, suffix + "0");
             return Expression.Lambda<Func<T, bool>>(exs, e);
         }
@@ -202,22 +245,26 @@ private static Expression GetExpressionForField(Expression e, WhereFilter filter
                         Field = t,
                         FilterType = filter.FilterType,
                         Value = filter.Value
-                    },
-                    suffix
+                    }, suffix
                     };
                     var expr = (Expression)generic.Invoke(null, pars);
-                    return Expression.Call(
+
+                    var call = Expression.Call(
                         CollectionAny2.MakeGenericMethod(
                         prop.Type.GenericTypeArguments.First()),
                         prop,
                         expr);
+
+                    return call;
+
                 }
                 prop = Expression.Property(prop, GetDeclaringProperty(prop, t));
             }
             var exp = GenerateExpressionOneField(prop, filter);
             return exp;
         }
 
+
         /// <summary>
         /// Construct bool-expression between different expression and a filter.
         /// </summary>
@@ -282,16 +329,13 @@ private static Expression GenerateExpressionOneField(Expression prop, WhereFilte
                 case WhereFilterType.Any:
                     if (IsEnumerable(prop))
                         prop = AsQueryable(prop);
-                    var ca = CollectionAny.MakeGenericMethod(
-                        prop.Type.GenericTypeArguments.First());
-                    return Expression.Call(ca, prop);
+
+                    return CreateMethodCall(prop, filter);
 
                 case WhereFilterType.NotAny:
                     if (IsEnumerable(prop))
                         prop = AsQueryable(prop);
-                    var cna = CollectionAny.MakeGenericMethod(
-                        prop.Type.GenericTypeArguments.First());
-                    return Expression.Not(Expression.Call(cna, prop));
+                    return Expression.Not(CreateMethodCall(prop, filter));
 
                 case WhereFilterType.IsNull:
                     return Expression.Equal(prop, ToStaticParameterExpressionOfType(null, prop.Type));
@@ -326,10 +370,85 @@ private static Expression GenerateExpressionOneField(Expression prop, WhereFilte
                             Expression.Equal(prop, ToStaticParameterExpressionOfType(null, prop.Type)),
                             Expression.Equal(prop, ToStaticParameterExpressionOfType(string.Empty, prop.Type))));
 
+
+                case WhereFilterType.CountEquals:
+                    if (IsEnumerable(prop))
+                        prop = AsQueryable(prop);
+
+                    return Expression.Equal(CreateMethodCall(prop, filter), Expression.Constant(filter.Value, IntType));
+
+                case WhereFilterType.CountGreaterThan:
+                    if (IsEnumerable(prop))
+                        prop = AsQueryable(prop);
+
+                    return Expression.GreaterThan(CreateMethodCall(prop, filter), Expression.Constant(filter.Value, IntType));
+
+                case WhereFilterType.CountGreaterThanOrEqual:
+                    if (IsEnumerable(prop))
+                        prop = AsQueryable(prop);
+                    return Expression.GreaterThanOrEqual(CreateMethodCall(prop, filter), Expression.Constant(filter.Value, IntType));
+
+                case WhereFilterType.CountLessThan:
+                    if (IsEnumerable(prop))
+                        prop = AsQueryable(prop);
+                    return Expression.LessThan(CreateMethodCall(prop, filter), Expression.Constant(filter.Value, IntType));
+
+                case WhereFilterType.CountLessThanOrEqual:
+                    if (IsEnumerable(prop))
+                        prop = AsQueryable(prop);
+                    return Expression.LessThanOrEqual(CreateMethodCall(prop, filter), Expression.Constant(filter.Value, IntType));
+
                 default:
                     return prop;
             }
         }
+        /// <summary>
+        /// Create method call with different expression
+        /// </summary>
+        /// <param name="prop">Different expression.</param>
+        /// <param name="filter">Filter for query.</param>
+        /// <returns>Method call expression.</returns>
+        private static MethodCallExpression CreateMethodCall(Expression prop, WhereFilter filter)
+        {
+            var methods = FilterTypeAvaliableMethods[filter.FilterType];
+
+
+            var mf = methods[0].MakeGenericMethod(
+                     prop.Type.GenericTypeArguments.First());
+
+            var mf2 = methods[1].MakeGenericMethod(
+                       prop.Type.GenericTypeArguments.First());
+
+
+            return filter.OperandsOfCollections == null ?
+                    Expression.Call(mf, prop) :
+                    Expression.Call(mf2, prop, CreateCollectionMethodExpression(filter.OperandsOfCollections, prop.Type.GenericTypeArguments.First()));
+
+        }
+
+
+        /// <summary>
+        /// Create expression for collection methods
+        /// </summary>
+        /// <param name="filter">Filter value.</param>
+        /// <param name="type">Conversion to type.</param>
+        /// <param name="suffix">Suffix vor variable.</param>
+        /// <returns>Converted value.</returns>
+        private static Expression CreateCollectionMethodExpression(TreeFilter filter, Type type, string suffix = "")
+        {
+
+            var generic = ExpressionTreeMethod.MakeGenericMethod(type);
+
+            object[] pars = {
+                     filter
+                     ,suffix+"0"
+                    };
+            var expr = (Expression)generic.Invoke(null, pars);
+
+            return expr;
+
+        }
+
 
         /// <summary>
         /// Value type filter field conversion.
@@ -383,7 +502,7 @@ private static object TryCastFieldValueType(object value, Type type)
         private static Expression ToStaticParameterExpressionOfType(object obj, Type type)
             => Expression.Convert(
                 Expression.Property(
-                    Expression.Constant(new { obj }), 
+                    Expression.Constant(new { obj }),
                     "obj"),
                 type);
 

src/QueryDesignerCore/WhereFilter.cs

@@ -27,5 +27,11 @@ public WhereFilter()
         /// Value for filtering.
         /// </summary>
         public object Value { get; set; }
+
+        /// <summary>
+        /// Operands of collection boolean expressions.
+        /// </summary>
+        public TreeFilter OperandsOfCollections { get; set; }
+
     }
 }

src/QueryDesignerCore/WhereFilterType.cs

@@ -108,6 +108,38 @@ public enum WhereFilterType
         /// <summary>
         /// The field is not null or empty
         /// </summary>
-        IsNotNullOrEmpty
+        IsNotNullOrEmpty,
+
+
+        /// <summary>
+        /// Collection count equal the value.
+        /// </summary>
+        CountEquals,
+
+
+        /// <summary>
+        /// Collection count less than the value.
+        /// </summary>
+        CountLessThan,
+
+         /// <summary>
+        /// Collection count is  less than or equal to value.
+        /// </summary>
+        CountLessThanOrEqual,
+
+        /// <summary>
+        /// Collection count greater than the value.
+        /// </summary>
+        CountGreaterThan,
+
+
+
+        /// <summary>
+        /// Collection count is greater than or equal to the value.
+        /// </summary>
+        CountGreaterThanOrEqual,
+
+
+
     }
 }