How to apply Expression value selector in query?

Asked Aug 08 '23 at 15:58

Active Aug 08 '23 at 15:58

Viewed 25 times

I have such code:

private static IQueryable<Word> filterAndOrderWords(IQueryable<Word> words, string phrase)
{
  return words
    .Where(it => it.Phrase.ToLower().Contains(phrase))
               ...

which now I would like to make more generic and remove hard coded using Phrase property. So I could change it to:

private static IQueryable<T> filterAndOrderText<T>(IQueryable<T> textRecords,
  Expression< Func<T,string>> selector, string phrase)
{
  return textRecords
    .Where(it => selector(it).ToLower().Contains(phrase))
    ...

But this does not compile. selector.Compile()(it) throws an exception (I used EF SQlite as source, and the message is I should rewrite the query).

So how to rewrite it so EF could understand the more generic version as well as the original one?

asked Aug 08 '23 at 15:58

greenoldman

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Are you ready to use `LINQKit` for such task or you need pure implementation? – Svyatoslav Danyliv Aug 08 '23 at 16:09
1

With `LINQKit` it is simple ` .Where(it => selector.Invoke(it).ToLower().Contains(phrase))` – Svyatoslav Danyliv Aug 08 '23 at 16:10
@SvyatoslavDanyliv Pure implementation. I mean I can use library, but I would like to learn how to do it. – greenoldman Aug 08 '23 at 16:27
[Sample](https://stackoverflow.com/a/72099548/10646316) how to activate LINQKit and use `Invoke` – Svyatoslav Danyliv Aug 08 '23 at 16:36

How to apply Expression value selector in query?

0 Answers0