CODEWITHSUNDEEP
linqselect
lintmouse
lintmouse

Reputation: 5119

LINQ .Select() Accessing parent properties?

I didn't know how to phrase the title of this post. This is what I am trying to do:

invalidItems.AddRange(documents.SelectMany(doc => doc.Messages)
            .Select(message => string.Format("Doc. Key {0}: {1}", doc.ID, message)));

Where invalidItems is a List and Document is a class that contains a List property called messages.

I want to get a flat list of the messages (strings) for all of the documents, where the strings are formatted to include the Document ID (similar to the String.Format() above). Is there a way to accomplish this?

When I working with the message parameter in the final .Select() clause, I am unable to access anything on the parent Document...

Upvotes: 2

Views: 449

Answers (2)

Amy B
Amy B

Reputation: 110111

If you want more scope in your queries, query comprehension syntax may be the way to go.

from doc in documents
from message in doc.Messages
select string.Format("Doc. Key {0}: {1}", doc.ID, message)

which is equivalent to:

documents
.SelectMany(
  doc => doc.Messages,
  (doc, message) => new {doc, message}
)
.Select(
  x => string.Format("Doc. Key {0}: {1}", x.doc.ID, x.message)
)

Upvotes: 0

Botz3000
Botz3000

Reputation: 39610

You just need to move the select clause into your SelectMany clause like this: 

documents.SelectMany(
    doc => doc.Messages.Select(
        message => string.Format("Doc. Key {0}: {1}", doc.ID, message)
    )
);

Upvotes: 1

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