CSOM SP 2013 - Retrieving a document by ID using folders (not lists)

Question

I'm trying to retrieve a document by its "_dlc_DocId" and I tried the suggestion at CSOM get document by ID but I end up with nothing (my "items" object is empty and I am sure my _dlc_DocId is correct).

In my case I have a root folder, and document sets (folders) within that folder. The files I'm looking for are within the document sets (sub-folders). Is there a way to retrieve a document by Id using a url (library path + ID)? Just looking for a more direct way other than brute force (iterating over each sub-folder, loading the files for each folder, and then iterating over the files for an ID match).

Answer 1

Try to using below caml query,

camlQuery.ViewXml = "<View><Query><Where><And><Eq><FieldRef Name='_dlc_DocId' /><Value Type='Text'>Your_dlc_DocId</Value></Eq><BeginsWith><FieldRef Name='ContentTypeId' /><Value Type='ContentTypeId'>0x0120</Value></BeginsWith></And></Where></Query></View>"

Folder Content Type ID starts with 0x0120.

Answer 2

The CAML query needs to be recursive to query items in folders:

<View Scope='Recursive'>
    <Query>
        <Where>
            <Eq>
                <FieldRef Name='_dlc_DocId' />
                <Value Type='Text'>UNIQUEID</Value>
            </Eq>
        </Where>
    </Query>
</View>