动态表达式 API：我可以做谓词，如何编写 OrderBy 规范？

发布于 2024-11-26 19:53:54 字数 1359 浏览 2 评论 0原文

我想出了如何根据客户端提供的字符串进行谓词 Dynamic Linq （这被包装在规范对象中）：

return System.Linq.Dynamic.DynamicExpression.ParseLambda<TE, bool> 
       (filter.ToString(), arguments.ToArray())

其中过滤器是表达式语言的字符串，如其帮助中所述文件。就像魅力一样。

但是，是否可以将 orderby 字段的字符串列表转换为强类型表达式，如下所示：

Expression<Func<E, object>> orderby

注意：

这是我的存储库方法，用于过滤和排序项目，

public IList<E> Get(Expression<Func<E, bool>>   filterLambda = null,
                    Expression<Func<E, object>> orderbyLambda = null,
                    int? page = null, 
                    int? pageSize = null)

我想使用以下方式调用它：

var a = Repo.Get( filterLambda:  Specification.Where(   StringListOfFilters),
                  orderbyLambda: Specification.OrderBy( StringListOfOrderBy),
                  page: 1,
                  pageSize: 100 );

有关的任何想法如何将 OrderBy 字段的字符串列表转换为强类型 lambda 表达式？字符串的示例如下：

fieldname
fieldname descending

另请注意：

我正在翻译来自客户端的字符串，这些字符串是使用正则表达式验证它们以防止注入的 fieldname op value。另外，我仅在规范对象中引用 Dynamic Linq，而不是存储库。

原文

I figured out how to do a predicate from a string supplied by a client based on Dynamic Linq (this is wrapped in a Specification object):

return System.Linq.Dynamic.DynamicExpression.ParseLambda<TE, bool> 
       (filter.ToString(), arguments.ToArray())

where filter is a string of expression language as described in their help file. Works like a charm.

However, is it possible to translate a string list of orderby fields into a strongly typed expression like this:

Expression<Func<E, object>> orderby

Notes:

Here's my repository method to filter and order items

public IList<E> Get(Expression<Func<E, bool>>   filterLambda = null,
                    Expression<Func<E, object>> orderbyLambda = null,
                    int? page = null, 
                    int? pageSize = null)

I would like to call it using:

var a = Repo.Get( filterLambda:  Specification.Where(   StringListOfFilters),
                  orderbyLambda: Specification.OrderBy( StringListOfOrderBy),
                  page: 1,
                  pageSize: 100 );

Any ideas on how to convert a string list of OrderBy fields into a strongly typed lambda expression? Examples of the strings would be:

fieldname
fieldname descending

Another note:

I am translating the strings coming from the client, which are fieldname op value validating them with Regex to prevent injection. Also, I am only referencing Dynamic Linq in the Specification object, not the repository.

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