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👐 Add authors details to the books collection

👐 Add author name to the books collection​

We want to modify the MongoDB schema so that each book contains an array of its authors. Right now in the authorBooks mapping we're getting the authorId for the current book, but we want also the name of the author. So in this step we will embed the author name into array created from the mapping of the join table (which right now only contains authorId and bookId)

  • On the MongoDB diagram view, click the books collection
  • On the relational mappings list on the right, click + Add
  • Select Embedded documents
  • Select authors as Source table
  • In the advanced settings, check 'Merge fields into parent`
  • Check the name field and uncheck the rest
  • Click Save and close
Changes in the books collection

👐 Remove unneeded bookId from author details in books collection​

We want to modify the MongoDB schema so that each book contains an array of its authors. In this step we will remove the redundant ID fields from the join table (that you can see in authorBooks at the moment).

  • On the MongoDB diagram view, click the books collection.
  • On the relational mappings list on the right, click on the edit icon of author_book.
  • Edit the field name from authorBooks to just authors.
  • In the list of fields, uncheck bookId.
  • Click Save and close.

This results in our authors array looking like:

    "authors": [
        {
            "authorId": 8282,
            "name": "Cervantes"
        },
        ...
    ]
Changes in the books collection
info

This is a perfect example of the Extended Reference Pattern. When we read a book, we have some of the author's data (name in this case) but we still have the author's id in case we need all the author's attributes (we can then do a join on read using $lookup)