RFC: Allow language Tag support in GraphQL

Users GraphQL
8

GraphQL design with @dgraph directive

User needs to define different fields for different language tags that he want to use.
Example:

type Person {
         name: String   // Person.name is the corresponding dgraph field for this field
         nameHi: String @dgraph(pred:"Person.name@hi")
         nameEn: String @dgraph(pred:"Person.name@en")
         nameHi_En:  String @dgraph(pred:"Person.name@hi:en") // won't be added to mutation patch
         nameHi_En_untag:  String @dgraph(pred:"Person.name@hi:en:.") //won't be added to mutation patch
      
      }

We will add @lang in dgraph schema for the corresponding predicate automatically. User needs to give dgraph predicate name of the untagged field(name in this case) in @dgraph argument of language tag field. Dgraph predicate name for the corresponding graphql field typename.fieldname.

For example, in nameHi: String @dgraph(pred:"Person.name@hi") we have Person.name which is predicate in dgraph for the corresponding field name in graphql. If user give some other field name in argument then it won’t work as expected.

Note

  1. User needs to define all language fields at one place either in type or in the interface.
  2. We won’t be adding fields in mutation patch which have multiple language tags , for example field nameHi_En: String @dgraph(pred:"Person.name@hi:en") can only be queried.

Interaction with exiting directives for language tagged fields:

schema directives

@id : not required now, can be added in future .
@search: applicable only on one field(tagged or untagged value) and will apply on all gql fields which map to the same dgraph predicate.
@lambda: doesn’t work with @dgraph directive
@custom : doesn’t work with @dgraph directive
@hasinverse: doesn’t apply on string fields

query directives

@skip: Work normally as with other fields
@include: Work normally as with other fields