CODEWITHSUNDEEP
c#linq
Chris Yoker
Chris Yoker

Reputation: 61

add MAX to existing criteria in LINQ query

I have the folowing query that pulls an item from a list.

latestDoc = openDocs.Where(d => d.docBatchId == HARD_CODED_ID).FirstOrDefault();

I want to also find the row with the latestStatusDate...I'm using the MAX function but it returns null, as I believe Max is looking for the max of all the docs, I simply want it to find the max of the docs that contain this batchId

latestDoc = openDocs.Where(d => d.docBatchId == HARD_CODED_ID && d.prodStatus == openDocs.Max(d => d.ProdStatus)).FirstOrDefault();

Any ideas?

Ta, yogi

Upvotes: 0

Views: 56

Answers (3)

Baldy
Baldy

Reputation: 3659

The following c# compiles and runs in LinqPad...

    var openDocs = new [] {
    new { 
        docBatchId = 123,
        StatusDate = new DateTime(2014, 01, 01)
    },
    new {
        docBatchId = 123,
        StatusDate = new DateTime(2014, 01, 02)
    },
    new {
        docBatchId = 123,
        StatusDate = new DateTime(2014, 01, 03)
    }
    ,
    new {
        docBatchId = 456,
        StatusDate = new DateTime(2014, 01, 04)
    }
};

var HARD_CODED_ID = 123;

var latestDoc = (from doc in openDocs 
                where doc.docBatchId == HARD_CODED_ID
                select doc.StatusDate).Max();

latestDoc.Dump();

The result is 03/01/2014 00:00:00 (3rd January 2014), which is the latest statusDate for the 3 items with a docBatchId of 123.

Upvotes: 0

Kelly Robins
Kelly Robins

Reputation: 7288

I believe something like this will get you what you are looking for

var latestDoc = openDocs.Where(d => d.docBatchId == HARD_CODED_ID)
    .OrderByDescending(d => d.ProdStatus)
    .FirstOrDefault();

Upvotes: 0

Tim Schmelter
Tim Schmelter

Reputation: 460068

You can use OrderByDescending:

latestDoc = openDocs.Where(d => d.docBatchId == HARD_CODED_ID)
    .OrderByDescending(d => d.StatusDate)
    .FirstOrDefault();

Upvotes: 1

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