Description

If a table has a column with the array type then insert mutation to that table with returning its relationships throws an unexpected error.
As given in #3148:
For the following mutation:

mutation MyMutation {
  insert_site(objects: {name: "My Site"}, on_conflict: {constraint: site_name_key, update_columns: name}) {
    returning {
      id
      name
      site_trials {
        id
      }
    }
  }
}

Gives the following unexpected error:

{
  "errors": [
    {
      "extensions": {
        "path": "$.selectionSet.insert_site.args.objects",
        "code": "parse-failed"
      },
      "message": "A string is expected for type : _text"
    }
  ]
}

When relationship fields are found in returning fields, the server performs the mutation in two steps:

1. Mutate with returning all columns
2. Parse the returned column rows and query the returning fields.

Refer to commits 5f274b5 and 5bafdce to learn more about the above steps.

In step 2, parsing the array column values fails since our parser expects String representation of Postgres arrays. There are two ways to solve this problem

1. The PR native support for postgres array types (close #348) #2243 auto-fixes the problem since it has support for arrays. But seems like it is not going out any soon.
2. Perform the insert with returning the Postgres column values as Strings (except for geojson). It is kind of a hack and implemented in this PR.

Affected components

• Server
• Tests

Related Issues

Fix #3148 & #2520

Solution and Design

As mentioned in the above description, the mutated column values are returned as text.

Steps to test and verify

Follow the reproduction guide given in #3148 or #2520 and error shouldn't happen.

Limitations, known bugs & workarounds