Fix Merge Schemas behavior and remove legacy signature in addResolver…

…sToSchema (#4463)

* Fix Merge Schemas behavior and remove legacy signature in addResolversToSchema

* Go

* More improvements

* Go

* Satisfy Bob

* Try to fix website

* Try sth

.changeset/fifty-experts-unite.md

@@ -0,0 +1,76 @@
+---
+'@graphql-tools/schema': major
+---
+
+Thanks @mattkrick and @borisno2!
+
+## Breaking changes
+
+`addResolversToSchema`;
+
+If you are using the legacy parameters like below, you should update them to the new usage. Other than that, there is no functional change;
+
+```ts
+// From
+addResolversToSchema(schema, resolvers, resolverValidationOptions)
+
+// To
+addResolversToSchema({
+  schema,
+  resolvers,
+  resolverValidationOptions
+})
+```
+
+`mergeSchemas`;
+
+The provided `resolver` overrides the resolvers in the `schema` with the same name;
+
+The `hello` resolver in the `schema` would be overridden by the `hello` resolver in the `resolvers`. Before it was opposite which is not expected.
+
+```ts
+const schema = makeExecutableSchema({
+  typeDefs: `
+    type Query {
+      hello: String
+    }
+  `,
+  resolvers: {
+    Query: {
+      hello: () => 'Hello world!'
+    }
+  }
+})
+
+mergeSchemas({
+  schemas: [schema],
+  resolvers: {
+    Query: {
+      hello: () => 'New hello world'
+    }
+  }
+})
+```
+
+`makeExecutableSchema` no longer takes `parseOptions` and you can pass those options directly;
+
+```ts
+makeExecutableSchema({
+  typeDefs: ``,
+  parseOptions: {
+    assumeValid: true
+  }
+})
+
+// After
+makeExecutableSchema({
+  typeDefs: ``,
+  assumeValid: true
+})
+```
+
+`makeExecutableSchema` no longer does pruning and it doesn't take `pruningOptions` anymore.
+You can use `pruneSchema` from `@graphql-tools/utils` if you need.
+
+`extractExtensionsFromSchema` moved from `@graphql-tools/merge` to `@graphql-tools/schema`.
+And `travelSchemaPossibleExtensions` has been dropped in favor of `mapSchema`.

.changeset/tiny-zoos-dance.md

@@ -3,7 +3,7 @@
 '@graphql-tools/wrap': major
 ---
 
-Breaking changes;
+## Breaking changes
 
 **Schema generation optimization by removing `transfomedSchema` parameter**
 

packages/load/src/schema.ts

@@ -1,19 +1,12 @@
 import { loadTypedefs, LoadTypedefsOptions, UnnormalizedTypeDefPointer, loadTypedefsSync } from './load-typedefs.js';
-import {
-  GraphQLSchema,
-  BuildSchemaOptions,
-  DocumentNode,
-  Source as GraphQLSource,
-  print,
-  lexicographicSortSchema,
-} from 'graphql';
-import { OPERATION_KINDS } from './documents.js';
-import { mergeSchemas, MergeSchemasConfig } from '@graphql-tools/schema';
-import { Source } from '@graphql-tools/utils';
+import { GraphQLSchema, BuildSchemaOptions, Source as GraphQLSource, print, lexicographicSortSchema } from 'graphql';
+import { OPERATION_KINDS } from './documents';
+import { IExecutableSchemaDefinition, mergeSchemas, extractExtensionsFromSchema } from '@graphql-tools/schema';
+import { getResolversFromSchema, IResolvers, SchemaExtensions, Source, TypeSource } from '@graphql-tools/utils';
 
 export type LoadSchemaOptions = BuildSchemaOptions &
   LoadTypedefsOptions &
-  Partial<MergeSchemasConfig> & {
+  Partial<IExecutableSchemaDefinition> & {
     /**
      * Adds a list of Sources in to `extensions.sources`
      *
@@ -35,22 +28,7 @@ export async function loadSchema(
     ...options,
     filterKinds: OPERATION_KINDS,
   });
-
-  const { schemas, typeDefs } = collectSchemasAndTypeDefs(sources);
-  schemas.push(...(options.schemas ?? []));
-  const mergeSchemasOptions: MergeSchemasConfig = {
-    ...options,
-    schemas: schemas.concat(options.schemas ?? []),
-    typeDefs,
-  };
-
-  const schema = typeDefs?.length === 0 && schemas?.length === 1 ? schemas[0] : mergeSchemas(mergeSchemasOptions);
-
-  if (options?.includeSources) {
-    includeSources(schema, sources);
-  }
-
-  return options.sort ? lexicographicSortSchema(schema) : schema;
+  return getSchemaFromSources(sources, options);
 }
 
 /**
@@ -66,20 +44,7 @@ export function loadSchemaSync(
     filterKinds: OPERATION_KINDS,
     ...options,
   });
-
-  const { schemas, typeDefs } = collectSchemasAndTypeDefs(sources);
-
-  const schema = mergeSchemas({
-    schemas,
-    typeDefs,
-    ...options,
-  });
-
-  if (options?.includeSources) {
-    includeSources(schema, sources);
-  }
-
-  return options.sort ? lexicographicSortSchema(schema) : schema;
+  return getSchemaFromSources(sources, options);
 }
 
 function includeSources(schema: GraphQLSchema, sources: Source[]) {
@@ -98,20 +63,47 @@ function includeSources(schema: GraphQLSchema, sources: Source[]) {
   };
 }
 
-function collectSchemasAndTypeDefs(sources: Source[]) {
-  const schemas: GraphQLSchema[] = [];
-  const typeDefs: DocumentNode[] = [];
+function getSchemaFromSources(sources: Source[], options: LoadSchemaOptions) {
+  if (sources.length === 1 && sources[0].schema != null && options.typeDefs == null && options.resolvers == null) {
+    return options.sort ? lexicographicSortSchema(sources[0].schema) : sources[0].schema;
+  }
+  const { typeDefs, resolvers, schemaExtensions } = collectSchemaParts(sources);
+
+  const schema = mergeSchemas({
+    ...options,
+    typeDefs,
+    resolvers,
+    schemaExtensions,
+  });
+
+  if (options?.includeSources) {
+    includeSources(schema, sources);
+  }
+
+  return options.sort ? lexicographicSortSchema(schema) : schema;
+}
+
+function collectSchemaParts(sources: Source[]) {
+  const typeDefs: TypeSource[] = [];
+  const resolvers: IResolvers[] = [];
+  const schemaExtensions: SchemaExtensions[] = [];
 
   for (const source of sources) {
     if (source.schema) {
-      schemas.push(source.schema);
-    } else if (source.document) {
-      typeDefs.push(source.document);
+      typeDefs.push(source.schema);
+      resolvers.push(getResolversFromSchema(source.schema));
+      schemaExtensions.push(extractExtensionsFromSchema(source.schema));
+    } else {
+      const typeDef = source.document || source.rawSDL;
+      if (typeDef) {
+        typeDefs.push(typeDef);
+      }
     }
   }
 
   return {
-    schemas,
     typeDefs,
+    resolvers,
+    schemaExtensions,
   };
 }