add prefix and namespacing when adding remote schema

When adding a data source (v1.4+), the user should be able to give a prefix which is added to every type and root fields. This will allow adding sources which have same table names (i.e. have conflicting names), etc. The user should also be able to give a namespace so that the graph of the data source appears under that namespace field in root types.

The prefix/namespace ability should be available for remote schema (graphql data source) as well.

Type Prefixing

The types that need prefixing are:

• OBJECT
• INTERFACE
• UNION
• ENUM
• INPUT_OBJECT

Important points to note:

1. Scalar types should be skipped from prefixing as same named scalars are “mergeable”. UPDATE: See https://github.com/hasura/graphql-engine/issues/5863#issuecomment-700742259
2. Enum values should be skipped from prefixing.

Root fields i.e. fields under root types: query_root, mutation_root and subscription_root (or as defined by SCHEMA type) should also get the prefix. But non-root fields should not get any prefix.

Field Namespacing

When adding a source a namespace field can be given. If a namespace is given, then the fields of the source are added under that namespace respectively i.e. an object field with name <namespace> is added inside query_root, mutation_root and subscription_root and all the fields of the data source are added inside this object field.

For e.g., if the namespace is userservice:

query {
  userservice {
    getUser
}

mutation {
  userservice {
    deleteUser
}

Roadmap

Set of milestones for delivery.

POC

Current work in progress demonstrates the following:

• Optional prefix can be passed in on API calls to add a remote schema
• All types from the remote schema are prefixed except for __* and query_root, mutation_root, subscription_root.

The current branch (jberryman/5863-prep-refactoring-2) (as of 23/3/2021) is out of date with main and is being updated.

MVP

Additional features and changes:

• Default, per-source, and per-type naming configuration supported
• Tests for new functionality
• A new configuration format as described by Vamshi to be consumed by APIs and stored in metadata:

customization:
  # if root_fields_namespace is absent, the fields
  # are merged into the query root directly
  root_fields_namespace: "something"
  type_names:
    prefix: some_prefix
    suffix: some_suffix
    # mapping takes precedence over prefix and suffix
    mapping:
      old_name: new_name
  field_names:
    old_type_name:
      prefix: some_prefix
      suffix: some_suffix
      # mapping takes precedence over prefix and suffix
      mapping:
        old_name: new_name

V1

[samuelcastro]

@tirumaraiselvan Do you have an idea when this will be implemented?

[dmoverton]

PR for remote schema customization (https://github.com/hasura/graphql-engine-mono/pull/974) has been merged. There is a new issue for type name customization for database sources: https://github.com/hasura/graphql-engine/issues/6974.