CODEWITHSUNDEEP
c#linq
HelloWorld1
HelloWorld1

Reputation: 14100

Use Datatype List<Part> for Retrieving the Result

Goal:
Retrieve the variable ff as a datatype List<Part> after executing the code 

parts.GroupBy(b => new { b.PartName, b.PartId }).ToList();

The result should be three unique Part

Problem:
I tried a find solution but in the end it always end as the following code.

    List<Part> parts = new List<Part>();

    // Add parts to the list.
    parts.Add(new Part() { PartName = "crank arm", PartId = 1234 });
    parts.Add(new Part() { PartName = "crank arm", PartId = 1234 });
    parts.Add(new Part() { PartName = "chain ring", PartId = 1334 });
    parts.Add(new Part() { PartName = "regularseat", PartId = 1434 });



    var ff = parts.GroupBy(b => new { b.PartName, b.PartId }).ToList();

Thank you!

Upvotes: 0

Views: 56

Answers (2)

Adil Mammadov
Adil Mammadov

Reputation: 8676

You are missing Select statement:

List<Part> ff = parts
    .GroupBy(b => new { b.PartName, b.PartId })
    .Select(g => new Part
    {
        PartName = g.Key.PartName
        PartId = g.Key.PartId
    })
    .ToList();

Update

If your goal is just select distinc Part objects, then the GroupBy may be slower than Distinct (see this answer). But you have to test and see yourself. If you want to use Distinct then you have to create equality comparer by implementing IEqualityComparer interface. Be sure to check JonSkeet's answer for good GetHashCode method in case you choosed Distinct.

Upvotes: 1

Zortaniac
Zortaniac

Reputation: 141

You can select the first element from each group with Select. Then you have a flat list of Parts.

List<Part> parts = new List<Part>();

// Add parts to the list.
parts.Add(new Part() { PartName = "crank arm", PartId = 1234 });
parts.Add(new Part() { PartName = "crank arm", PartId = 1234 });
parts.Add(new Part() { PartName = "chain ring", PartId = 1334 });
parts.Add(new Part() { PartName = "regularseat", PartId = 1434 });



var ff = parts.GroupBy(b => new { b.PartName, b.PartId }).Select(group => group.First()).ToList();

Upvotes: 1

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