针对成员对象列表过滤LINQ查询

Question

I have an application that I inherited from a coworker that tracks feedback cards. I also have a form that filters the cards that are displayed on a web page based upon a number of user entered filters. All of the filters work fine, except the filter that is applied against feedback details (service was fine/bad, room was clean/dirty, etc). These are stored in list of a member class in my card class.

Below is a set of snippets of each class.

public class Card {
    public long ID { get; set; }
    public List<Feedback> feedback { get; set; }

    ...
}

public class Feedback {
    public long ID {get; set; }

    ...
}

public class CardFilter {
    public ICollection<long> FeedBackDetails {get; set; }

    ...
}

...
public IQueryable<CardType > GetFeedbackQueryable<CardType>(CardFilter filter = null)
        where CardType : Card
{
    var data = Service.GetRepository<CardType>();
    var CardQuery = data.All;
    ...
    if (filter.FeedbackDetails != null && filter.FeedbackDetails.Count != 0)
    {
        cardQuery = cardQuery.Where(card => card.FeedbackValues)
                             .All(fbv => filter.FeedbackDetails.Contains(fbv.ID));
    }
    return cardQuery;
}
...

When I try the filter:

cardQuery = cardQuery.Where(card => card.FeedbackValues)
                     .All(fbv => filter.FeedbackDetails.Contains(fbv.ID));

It returns the 15 card instances without any feedback. If I use the filter:

cardQuery = cardQuery.Where(card => card.FeedbackValues)
                     .Any(fbv => filter.FeedbackDetails.Contains(fbv.ID));

Nothing is returned, even though I can look through the data and see the appropriate cards.

I'm new to LINQ, so I know I'm missing something. Please point me in the right direction here.

EDIT:

To give a little more background on this application, I'll be a bit more verbose. The Card table/Model has the information about the card and the person submitting it. By that I mean name or anonymous, address, location being commented upon and a few other basic facts. The feedback items are listed in another table and displayed on the web form and the user can check either positive or negative for each. There are three possible answers for each feedback detail; 0 (positive), 1 (negative) or nothing (no answer).

The Card Model has all of the basic card information as well as a collection of feedback responses. My filter that is giving me trouble is against that collection of responses. Each card can have from 0 to 52 possible responses which may not apply to all situations, so I need to see all cards that are about a specific situation (cleanliness, etc.) whether they are positive or negative. That is the purpose of this filter.

Answer 1

var ifExist = YourList.Any(lambda expression) checking if YourList<T> contains object whitch fulifill lambda expression . It's only return true or false . If you want to have list of objects you should use var YourNewList = YourList.Where(lambda expression).ToList() .

Answer 2

Try this. Although I'm not entirely sure about your filter obj.

cardQuery = cardQuery.Query().Select(card => card.FeedbackValues).Where(fbv => filter.FeedbackDetails.Contains(fbv.ID));

Answer 3

You can't use the all statement, the predicate for this statement is if all values are identical to the id.

In your where statement, which is a filter clause, are you not filtering any thing.

And you are comparing feedbackvalues with an id? Are they the same? Can you post some more details about

Maybe try:

cardQuery = cardQuery.Where(card => filter. FeedbackDetails.Contains(card. Id/detsils))
                     .Select(se=> se).Tolist() ;

Answer 4

I was able to solve this. All of the answers that were posted helped me in the right direction. I wish I could have flagged them all as the answer.

I ended up reworking my Feedback model slightly to include another identity field from the database. It duplicated existing date (bad design, I know. It wasn't mine), but had a unique name. Using the new field, I was able to apply an Any filter. I guess I was confusing LINQ with multiple fields named ID. Once I used FeedbackID, it worked fine.