CODEWITHSUNDEEP
c#linq
Almis
Almis

Reputation: 3809

How to group by IEnumerable property value

Lets say I have

class Class1 A {
    int Id;
    IEnumerable<Class2> B;
}

class Class2 B {
    string Title;
}

So if I have (in json format)

{Id: 0, B: [{"Title": "a"}, {"Title": "b"}, {"Title": "c"} ]}

I want to group by Title so the result would be

 { {"Id": 0, "Title": "a"}, {"Id": 0, "Title": "b"}, {"Id": 0, "Title": "c"} };

Prefer a solution with LINQ. Tried to do:

var result = A.GroupBy(x => x.B)

(I expected that this will not work) and

var result = A.SelectMany(x => x.B).GroupBy(x => x)

but then I have only titles. How I can do that?

Upvotes: 3

Views: 283

Answers (1)

D Stanley
D Stanley

Reputation: 152501

You're not grouping, you're doing the opposite - flattening - which is done with SelectMany:

A.SelectMany(a => a.B, (a, b) => new {a.Id, b.Title});

Upvotes: 7

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