Select each int in array

Question

I have the following Linq query which is working fine.

var results = accounts.Select(a => new
{
    Id = a.Id,
    Scores = _context.AccountAttributeStatistics.Where(at => at.AccountId == a.Id 
                             && at.LatestVersion && at.AttributeId == 39)
        .Select(at => new
        {
            Id = at.AttributeId,
            Percentile = at.Percentile,
            Percentage = at.CurrentPercentage,
        }).ToList()
 });

However I now need to run this for a number if different AttributeIds. I have tried:

Scores = _context.AccountAttributeStatistics.Where(at => at.AccountId == a.Id 
                 && at.LatestVersion && at.AttributeId == 39 || at.AttributeId == 40 
                 || at.AttributeId == 41 || at.AttributeId == 42)

Unfortunately this seems to ignore the at.LatestVersion and returns all scores instead of the latest for these attributes.

What is the best way to get the desires results?

I have thought to use an array and use a foreach but not sure how this would work?

int[] attributeIds = {39, 40, 41, 42, 43};

Scores = _context.AccountAttributeStatistics.Where(at => at.AccountId == a.Id 
                 && at.LatestVersion && at.AttributeId == attributeIds.ForEach(x => x))

But get the error Only assignment, call, increment, decrement, and new object expressions can be used as a statement

Not sure if that would be the correct way, using linq, to achieve this anyway?

Mittal Patel · Accepted Answer · 2018-02-22 10:01:39Z

3

You need to add brackets for that. As you have used the || OR, so it takes all the records having the attributes 40, 41,42 without checking the latest one.

 Scores = _context.AccountAttributeStatistics.Where(at => (at.AccountId == a.Id 
             && at.LatestVersion) && (at.AttributeId == 39 || at.AttributeId == 40 
             || at.AttributeId == 41 || at.AttributeId == 42))

Either use:

 int[] attributeIds = {39,40,41,42};
 Scores = _context.AccountAttributeStatistics.Where(at => (at.AccountId == a.Id 
             && at.LatestVersion) && attributeIds.Contains(at.AttributeId))

edited Feb 22, 2018 at 10:01

answered Feb 22, 2018 at 9:57

Mittal Patel

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Tim Schmelter · Accepted Answer · 2018-02-22 09:58:30Z

3

In your query brackets were missing so that LatestVersion is included always. But i would use a collection for the allowed AttributeIds and use Enumerable.Contains:

int[] attributeIds = {39, 40, 41, 42, 43};

....
Scores = _context.AccountAttributeStatistics
    .Where(at => at.AccountId == a.Id 
              && at.LatestVersion 
              && attributeIds.Contains(at.AttributeId))
....

answered Feb 22, 2018 at 9:58

Tim Schmelter

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John Woo · Accepted Answer · 2018-02-22 09:57:18Z

1

You can use Contains(). This is the same as IN in sql.

.Where(at => at.AccountId == a.Id 
             && at.LatestVersion 
             && attributeIds.Contains(at.AttributeId))

answered Feb 22, 2018 at 9:57

John Woo

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Alex · Accepted Answer · 2018-02-22 09:57:54Z

1

Just a few additional parentheses would solve your problem:

Scores = _context.AccountAttributeStatistics.Where(at => at.AccountId == a.Id 
                     && at.LatestVersion && (at.AttributeId == 39 || at.AttributeId == 40 
                     || at.AttributeId == 41 || at.AttributeId == 42))

answered Feb 22, 2018 at 9:57

Alex

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