fix(gatsby): improve deprecation text for missing childOf directive (#28532) (#28543)

* fix(gatsby): improve deprecation text for missing childOf directive

* text formatting

* Add "many" argument

(cherry picked from commit f733f4e)

Co-authored-by: Vladimir Razuvaev <[email protected]>

Author: GatsbyJS Bot

packages/gatsby/src/schema/extensions/__tests__/child-relations.js

@@ -174,13 +174,13 @@ describe(`Define parent-child relationships with field extensions`, () => {
     )
     await buildSchema()
     expect(report.warn).toBeCalledTimes(1)
-    expect(report.warn).toBeCalledWith(
-      `The type \`Parent\` does not explicitly define the field \`childChild\`.\n` +
-        `On types with the \`@dontInfer\` directive, or with the \`infer\` ` +
-        `extension set to \`false\`, automatically adding fields for ` +
-        `children types is deprecated.\n` +
-        `In Gatsby v3, only children fields explicitly set with the ` +
-        `\`childOf\` extension will be added.\n`
+    expect(report.warn.mock.calls[0][0]).toEqual(
+      `Deprecation warning: In Gatsby v3 field \`Parent.childChild\` will not be added automatically ` +
+        `because type \`Child\` does not explicitly list type \`Parent\` in \`childOf\` extension.\n` +
+        `Add the following type definition to fix this:\n\n` +
+        `  type Child implements Node @childOf(types: ["Parent"]) {\n` +
+        `    id\n` +
+        `  }`
     )
   })
 

packages/gatsby/src/schema/schema.js

@@ -1042,14 +1042,15 @@ const addImplicitConvenienceChildrenFields = ({
         const fieldName = many
           ? fieldNames.convenienceChildren(typeName)
           : fieldNames.convenienceChild(typeName)
+        const manyArg = many ? `, many: true` : ``
         report.warn(
-          `The type \`${parentTypeName}\` does not explicitly define ` +
-            `the field \`${fieldName}\`.\n` +
-            `On types with the \`@dontInfer\` directive, or with the \`infer\` ` +
-            `extension set to \`false\`, automatically adding fields for ` +
-            `children types is deprecated.\n` +
-            `In Gatsby v3, only children fields explicitly set with the ` +
-            `\`childOf\` extension will be added.\n`
+          `Deprecation warning: ` +
+            `In Gatsby v3 field \`${parentTypeName}.${fieldName}\` will not be added automatically because ` +
+            `type \`${typeName}\` does not explicitly list type \`${parentTypeName}\` in \`childOf\` extension.\n` +
+            `Add the following type definition to fix this:\n\n` +
+            `  type ${typeName} implements Node @childOf(types: ["${parentTypeName}"]${manyArg}) {\n` +
+            `    id\n` +
+            `  }`
         )
       }
     }