public static TestAttribute Test()
{
TestAttribute testAttribute = CustomAttributeExtension <TestAttribute> .GetCustomAttributeValue(typeof(TestEntity));
return(testAttribute);
}
/// <summary>
/// 获取动态表达式
/// </summary>
/// <typeparam name="TResult">表达式数据类型</typeparam>
/// <typeparam name="TCondition">表达式条件类型</typeparam>
/// <param name="data">数据</param>
/// <param name="condtion">条件</param>
/// <returns>表达式</returns>
public static Expression <Func <TResult, bool> > GetDynamicExpression <TResult, TCondition>(this IEnumerable <TResult> data, TCondition condtion)
where TResult : class
where TCondition : class
{
Type tConditionType = typeof(TCondition);
Type tResultType = typeof(TResult);
Expression totalExpr = Expression.Constant(true);
ParameterExpression param = Expression.Parameter(typeof(TResult), "n");
foreach (PropertyInfo property in tConditionType.GetProperties())
{
string key = property.Name;
object value = property.GetValue(condtion);
if (value != null && value.ToString() != string.Empty)
{
DynamicExpressionAttribute dynamicExpressionAttribute = CustomAttributeExtension <DynamicExpressionAttribute> .GetCustomAttributeValue(tConditionType, property);
//等式左边的值
string name = dynamicExpressionAttribute.Name ?? key;
Expression left = Expression.Property(param, tResultType.GetProperty(name));
//等式右边的值
Expression right = Expression.Constant(value);
Expression filter;
switch (dynamicExpressionAttribute.Operator)
{
case "!=":
filter = Expression.NotEqual(left, right);
break;
case ">":
filter = Expression.GreaterThan(left, right);
break;
case ">=":
filter = Expression.GreaterThanOrEqual(left, right);
break;
case "<":
filter = Expression.LessThan(left, right);
break;
case "<=":
filter = Expression.LessThanOrEqual(left, right);
break;
case "Contains":
filter = Expression.Call(Expression.Property(param, tResultType.GetProperty(name)), typeof(string).GetMethod("Contains", new [] { typeof(string) }), Expression.Constant(value));
break;
default:
filter = Expression.Equal(left, right);
break;
}
totalExpr = Expression.And(filter, totalExpr);
}
}
var predicate = Expression.Lambda(totalExpr, param);
//var dynamic = (Func<TResult, bool>)predicate.Compile();
var dynamic = (Expression <Func <TResult, bool> >)predicate;
return(dynamic);
}
