c#反射表达式树模糊搜索示例

复制代码 代码如下:
public static expression> GetSearchexpression(string SearchString)
        {
            expression> filter = null;

            if (string.IsNullOrEmpty(SearchString)) return null;
            var left = expression.Parameter(typeof(T), "m");

            expression expression = expression.Constant(false);
            T obj = default(T);
            var type = typeof(T);
            obj = (T)Activator.CreateInstance(type);
           var propertyInfos = type.GetProperties();

            foreach (var propertyInfo in propertyInfos)
            {

                if (propertyInfo.Name.ToLower() == "id" || propertyInfo.PropertyType == typeof(DateTime)) continue;
                expression tostring = expression.Call
         (
            expression.Property(left, typeof(T).GetProperty(propertyInfo.Name).Name),

           typeof(object).GetMethod("ToString", new Type[] { })

         );
                expression right = expression.Call

                      (

                          tostring,

                        typeof(string).GetMethod("Contains", new Type[] { typeof(string) }),

                        expression.Constant(SearchString)

                      );
                expression = expression.Or(right, expression);
            }

            filter = expression.Lambda>(expression, new[] { left });

            return filter;

        }