/// <summary>
/// 操作
/// </summary>
/// <param name="left">左操作数</param>
/// <param name="operator">运算符</param>
/// <param name="value">值</param>
public static Expression Operation(this Expression left, OperatorLmada @operator, object value)
{
switch (@operator)
{
case OperatorLmada.Equal:
return(left.Equal(value));
case OperatorLmada.NotEqual:
return(left.NotEqual(value));
case OperatorLmada.Greater:
return(left.Greater(value));
case OperatorLmada.GreaterEqual:
return(left.GreaterEqual(value));
case OperatorLmada.Less:
return(left.Less(value));
case OperatorLmada.LessEqual:
return(left.LessEqual(value));
case OperatorLmada.Starts:
return(left.StartsWith(value));
case OperatorLmada.Ends:
return(left.EndsWith(value));
case OperatorLmada.Contains:
return(left.Contains(value));
}
throw new NotImplementedException();
}
/// <summary>
/// 添加表达式
/// </summary>
/// <param name="property">属性名</param>
/// <param name="operator">运算符</param>
/// <param name="value">值</param>
public void Append(string property, OperatorLmada @operator, object value)
{
_result = _result.And(_parameter.Property(property).Operation(@operator, value));
}
/// <summary>
/// 添加表达式
/// </summary>
/// <typeparam name="TProperty">属性类型</typeparam>
/// <param name="propertyExpression">属性表达式</param>
/// <param name="operator">运算符</param>
/// <param name="value">值</param>
public void Append <TProperty>(Expression <Func <TEntity, TProperty> > propertyExpression, OperatorLmada @operator,
object value)
{
_result = _result.And(_parameter.Property(LambdaHelper.GetMember(propertyExpression))
.Operation(@operator, value));
}
/// <summary>
/// 解析为谓词表达式
/// </summary>
/// <typeparam name="T">实体类型</typeparam>
/// <param name="propertyName">属性名</param>
/// <param name="value">值</param>
/// <param name="operator">运算符</param>
/// <returns></returns>
public static Expression <Func <T, bool> > ParsePredicate <T>(string propertyName, object value, OperatorLmada @operator)
{
var parameter = Expression.Parameter(typeof(T), "t");
return(parameter
.Property(propertyName)
.Operation(@operator, value)
.ToLambda <Func <T, bool> >(parameter));
}