采用全新的数据库架构

Infrastructure/PredicateBuilder.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Linq;
+using System.Linq.Expressions;
+
+namespace Infrastructure
+{
+    public static class PredicateBuilder
+    {
+        public static Expression<Func<T, bool>> True<T>() { return f => true; }
+        public static Expression<Func<T, bool>> False<T>() { return f => false; }
+
+        public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> expr1,
+            Expression<Func<T, bool>> expr2)
+        {
+            var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>());
+            return Expression.Lambda<Func<T, bool>>
+                (Expression.OrElse(expr1.Body, invokedExpr), expr1.Parameters);
+        }
+
+        public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> expr1,
+            Expression<Func<T, bool>> expr2)
+        {
+            var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>());
+            return Expression.Lambda<Func<T, bool>>
+                (Expression.AndAlso(expr1.Body, invokedExpr), expr1.Parameters);
+        }
+    }
+}