validation/schema: Allow deriving from interface-typed fields

The source of a derived field used to be restricted to just the type that
contained the derived field. With this change, it is also permissible to
use an interface that is implemented by the type containing the derived
field.

This mirrors the fix from this PR in graph-node:
graphprotocol/graph-node#1278

Author: lutter

src/validation/schema.js

@@ -339,7 +339,9 @@ does not exist on type '${targetEntity.name.value}'`,
   let backrefTypeName = unwrapType(derivedFromField.type)
   let backRefEntity = entityTypeByName(defs, backrefTypeName.name.value)
 
-  if (!backRefEntity || backRefEntity.name.value !== def.name.value) {
+  // The field we are deriving from must either have type 'def' or one of the
+  // interface types that 'def' is implementing
+  if (!backRefEntity || (backRefEntity.name.value !== def.name.value && !def.interfaces.find(intf => intf.name.value === backRefEntity.name.value))) {
     return immutable.fromJS([
       {
         loc: directive.loc,
@@ -348,7 +350,8 @@ does not exist on type '${targetEntity.name.value}'`,
 Field '${field.name.value}': \
 @derivedFrom field '${directive.arguments[0].value.value}' \
 on type '${targetEntity.name.value}' must have the type \
-'${def.name.value}', '${def.name.value}!' or '[${def.name.value}!]!'`,
+'${def.name.value}', '${def.name.value}!', '[${def.name.value}!]!', \
+or one of the interface types that '${def.name.value}' implements`,
       },
     ])
   }

tests/cli/validation.test.js

@@ -120,6 +120,14 @@ describe('Validation', () => {
       exitCode: 1,
     },
   )
+  cliTest(
+    'Deriving from interface-typed fields is allowed',
+    ['codegen', '--skip-migrations'],
+    'validation/derived-from-with-interface',
+    {
+      exitCode: 0,
+    },
+  )
   cliTest(
     '@derivedFrom target type missing',
     ['codegen', '--skip-migrations'],

tests/cli/validation/derived-from-with-interface/Gravity.json

@@ -0,0 +1 @@
+[{"constant":false,"inputs":[{"name":"_imageUrl","type":"string"}],"name":"updateGravatarImage","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[],"name":"setMythicalGravatar","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"owner","type":"address"}],"name":"getGravatar","outputs":[{"name":"","type":"string"},{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"uint256"}],"name":"gravatarToOwner","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"address"}],"name":"ownerToGravatar","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_displayName","type":"string"}],"name":"updateGravatarName","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_displayName","type":"string"},{"name":"_imageUrl","type":"string"}],"name":"createGravatar","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"","type":"uint256"}],"name":"gravatars","outputs":[{"name":"owner","type":"address"},{"name":"displayName","type":"string"},{"name":"imageUrl","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"anonymous":false,"inputs":[{"indexed":false,"name":"id","type":"uint256"},{"indexed":false,"name":"owner","type":"address"},{"indexed":false,"name":"displayName","type":"string"},{"indexed":false,"name":"imageUrl","type":"string"}],"name":"NewGravatar","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"id","type":"uint256"},{"indexed":false,"name":"owner","type":"address"},{"indexed":false,"name":"displayName","type":"string"},{"indexed":false,"name":"imageUrl","type":"string"}],"name":"UpdatedGravatar","type":"event"}]

tests/cli/validation/derived-from-with-interface/mapping.ts

@@ -0,0 +1,22 @@
+import { NewGravatar, UpdatedGravatar } from '../generated/Gravity/Gravity'
+import { Gravatar } from '../generated/schema'
+
+export function handleNewGravatar(event: NewGravatar): void {
+  let gravatar = new Gravatar(event.params.id.toHex())
+  gravatar.owner = event.params.owner
+  gravatar.displayName = event.params.displayName
+  gravatar.imageUrl = event.params.imageUrl
+  gravatar.save()
+}
+
+export function handleUpdatedGravatar(event: UpdatedGravatar): void {
+  let id = event.params.id.toHex()
+  let gravatar = Gravatar.load(id)
+  if (gravatar == null) {
+    gravatar = new Gravatar(id)
+  }
+  gravatar.owner = event.params.owner
+  gravatar.displayName = event.params.displayName
+  gravatar.imageUrl = event.params.imageUrl
+  gravatar.save()
+}

tests/cli/validation/derived-from-with-interface/schema.graphql

@@ -0,0 +1,19 @@
+type Gravatar @entity {
+  id: ID!
+  # This field points at an interface; we allow that a derived field
+  # in a type that implements the interface derives from this field
+  # The test checks that this construct is accepted
+  owner: Account!
+  imageUrl: String!
+}
+
+interface Account {
+  id: ID!
+  gravatars: [Gravatar!]! @derivedFrom(field: "owner")
+}
+
+type UserAccount implements Account @entity {
+  id: ID!
+  name: String!
+  gravatars: [Gravatar!]! @derivedFrom(field: "owner")
+}

tests/cli/validation/derived-from-with-interface/subgraph.yaml

@@ -0,0 +1,25 @@
+specVersion: 0.0.2
+schema:
+  file: ./schema.graphql
+dataSources:
+  - kind: ethereum/contract
+    name: Gravity
+    network: mainnet
+    source:
+      address: '0x2E645469f354BB4F5c8a05B3b30A929361cf77eC'
+      abi: Gravity
+    mapping:
+      kind: ethereum/events
+      apiVersion: 0.0.4
+      language: wasm/assemblyscript
+      entities:
+        - Gravatar
+      abis:
+        - name: Gravity
+          file: ./Gravity.json
+      eventHandlers:
+        - event: NewGravatar(uint256,address,string,string)
+          handler: handleNewGravatar
+        - event: UpdatedGravatar(uint256,address,string,string)
+          handler: handleUpdatedGravatar
+      file: ./mapping.ts

tests/cli/validation/missing-or-invalid-derived-from-fields.stderr

@@ -7,4 +7,4 @@
   - Field 'd': @derivedFrom directive must have a 'field' argument
   - Field 'e': @derivedFrom directive must have a 'field' argument
   - Field 'f': Value of the @derivedFrom 'field' argument must be a string
-  - Field 'g': @derivedFrom field 'a' on type 'G' must have the type 'A', 'A!' or '[A!]!'
+  - Field 'g': @derivedFrom field 'a' on type 'G' must have the type 'A', 'A!', '[A!]!', or one of the interface types that 'A' implements