Schema migration default values for fields

Issues GraphQL
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4

Hi there, just wanted to bump this thread a bit as I think it deserves more attention.

Let’s assume my application is deployed with a “finished” schema and dgraph is running successfully doing it’s thing.

Now we can push new features in very short timeframes like we could never do before (because dgraph-gql is just awesome). New features will ultimately almost always bring new data to the database.

Now of course I could set the default values in the application layer. This however is error prone and in every new *.tsx I write I have to remember for which fields of which types I have to define default values. This can get out of hands very quickly.

Secondly, assume this schema:

type UserPermissions {
   ... 
   canUseFeatures: [String!]! # new field
}

So, I added the field canUseFeatures to my type which is required (!). When I migrate this schema to my existing database, currently all existing nodes will have null on that field. Querying those nodes will result in error: canUseFeatures has to be specified! (or something along these lines). The graphql schema validation fails.

Therefore, I once again propose to add a @default directive that is either used to:

  1. Set the corresponding field when the client is not specifying a value in the addType mutation
  2. Set the corresponding field to the default value for all existing nodes of the type in question.