I have three microservices: Service A, Service B, and Service C in Apollo GraphQl Federation. All services have database models which are Model A, Model B, Model C. Every service has its own DB.
Model A has a field bIds that holds ID array of B model. Model B has a field cIds that holds ID array of C model.
I write a query which returns list of A. In every A has list of B and every element of B has list of C.
Schema (typeDef) of Service A:
type A @key(fields: "id") {
id: ID!
bIds: [ID]
}
Schema of Service B:
type B @key(fields: "id") {
id: ID!
cIds: [ID]
}
extend type A @key(fields: "id") {
id: ID! @external
bList: [B]
}
Schema of Service C:
type C @key(fields: "id") {
id: ID!
}
extend type B @key(fields: "id") {
id: ID! @external
cList: [C]
}
It is simple. My problem is that I want a field in Model A which returns list of Model C which consist all cList elements of bList something like that:
extend type A @key(fields: "id") {
id: ID! @external
bList: [B]
derivedCList: [C] @requires(fields: "bList")
}
Resolver of derivedCList must fetch bList frield from A. How can I implement it? fields of @requires need to be @external. bList is not external. It has resolver in the Service B. If I extend type A in Service B with bList field which has @external declerative, Apollo throws exception about it.
