CODEWITHSUNDEEP
arraysmongodbuniquedynamic-queries
hewiefreeman
hewiefreeman

Reputation: 1187

MongoDB multiple arrays with unique values

I've run into a slight dilemma creating the schema and setting up my database the "right" way. I have a collection that contains objects which holds 4 different arrays. The objects in the collection entries looks similar to:

itemInCollection{
    ...
    theObj: {arr1: ["user1685", "user5342"], arr2: ["user1432"], arr3: [], arr4: ["user1632", "user2312", "user6452"]},
    ...
}

The schema I made already requires all array items to be unique, but I also want none of the arrays to contain the same entry as another. I also need to sometimes move an item that's already in one array to another array (and of course delete the entry from the old array because none of the arrays should contain the same entry). This is obviously not the best way to keep track of something like this, or is it?

What I have so far is 4 queries that check each array individually for a certain entry, and another query that adds the entry to the corresponding array if no entry was found... and ANOTHER query that would delete the entry that might have been found in another before adding it to a different array.

Is there a better way to set up the database to keep track of something like this? Or is there a dynamic way of querying multiple arrays instead of using 6-7 different queries?

Thanks to all in advance for you time and help :)

Upvotes: 0

Views: 128

Answers (1)

dnickless
dnickless

Reputation: 10918

You could structure your "user" data as subdocuments instead of as strings like this:

itemInCollection{
    ...
    theObj: [
        { userid: "user1685", type: "arr1" },
        { userid: "user5342", type: "arr1" },
        { userid: "user1432", type: "arr2" },
        { userid: "user1632", type: "arr4" },
        { userid: "user2312", type: "arr4" },
        { userid: "user6452", type: "arr4" }
    ],
    ...
}

With this structure in place, it should be easier to ensure uniqueness (at this stage, unfortunately, there is no way to ensure uniqueness of a particular field inside an array - see this link).

Upvotes: 3

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