mergeSchema - fragments don't query fields added during merge

[goldensunliu]

During resolve, if the fragment includes fields added/extended during the merge are not queried for.
here is a simple example forked from the Doc's Example

LaunchPad Example

the basic idea is now type User also has a new field chripCount which infers its value for the extended field chirps by doing:

      chripCount: {
        fragment: 'fragment UserInferringFragment on User { id chirps }',
        resolve(parent) {
          return parent.chrips && parent.chrips.length
        }
      }

this field will always resolve to be 'null'. Looks like the chrips field never got resolved

[marktani]

Looks like the root issue of this one: prisma-labs/graphql-prisma-typescript#91

[freiksenet]

It can't really work this way atm. It's kinda a chicken and egg problem. fragment param works in a way that they modify a query to subschema. If the field doesn't exist in subschema, naturally it won't be queried. It's not possible to modify the running query inside a running graphql executor. In order for this to work, one should modify the query that is applied to the merged schema. In #527, you could try to apply transforms on the merged schema to do it.

[freiksenet]

You could also just use delegateToSchema when calling mergedSchema, instead of querying it with GraphQL, this way you could pass fragment replacements that should happen on merged schema level.

[goldensunliu]

@freiksenet thanks! I will keep an eye on the merge