fix(HoistField): allow hoisting to root

requires passing additional parameters to each transformSchema call beyond the subschemaConfig: the transforms, and the transformedSchema. Because transformSchema may need to create additional proxying resolvers, it needs all the parameters that would be passed to delegateToSchema. It is NOT a catch-22 that transformSchema requires the transformed schema as a parameter, because it does NOT require an executable transformedSchema as a parameter, only the non-executable version for type comparisions performed ultimately by delegateToSchema within the proxying process.
ardatan · Oct 1, 2020 · e3083d7 · e3083d7
1 parent fda89db
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diff --git a/.changeset/weak-peaches-count.md b/.changeset/weak-peaches-count.md
@@ -11,7 +11,7 @@
 Breaking Changes:
 - Delegation result: ExternalObject concept formalized and matured, resulting in deprecation of slicedError, getErrors, getErrorsByPathSegment functions, see new getUnpathedErrors function for errors that cannot be merged into the ExternalObject. See as well new annotateExternalObject and mergeExternalObjects functions. Rename handleResult to resolveExternalValue.
 
-- Transforms: transforms now take delegationContext and transformationContext arguments within their transformRequest/Result methods and take an optional subschemaConfig as the second argument for transformSchema. Transform types and applySchemaTransforms now within delegate package; applyRequest/ResultTransforms functions deprecated.
+- Transforms: transforms now take delegationContext and transformationContext arguments within their transformRequest/Result methods. the transformSchema method may wish to create additional delegating resolvers and so it takes the subschemaConfig, transforms, and (non-executable) transformed schema as optional parameters. Transform types and applySchemaTransforms now within delegate package; applyRequest/ResultTransforms functions deprecated.
 
 - Wrapping schema standardization: remove support for createMergedResolver and non-standard transforms where resolvers do not use defaultMergedResolver. This is still possible, but not supported out of the box due to conflicts with type merging, where resolvers expected to be identical across subschemas.
 

diff --git a/packages/delegate/src/Subschema.ts b/packages/delegate/src/Subschema.ts
@@ -89,7 +89,7 @@ export class Subschema<K = any, V = any, C = K> {
 
     this.createProxyingResolver = config.createProxyingResolver;
     this.transforms = config.transforms ?? [];
-    this.transformedSchema = applySchemaTransforms(this.schema, this.transforms, config);
+    this.transformedSchema = applySchemaTransforms(this.schema, config);
 
     this.merge = config.merge;
   }

diff --git a/packages/delegate/src/applySchemaTransforms.ts b/packages/delegate/src/applySchemaTransforms.ts
@@ -6,12 +6,25 @@ import { SubschemaConfig, Transform } from './types';
 
 export function applySchemaTransforms(
   originalWrappingSchema: GraphQLSchema,
-  transforms: Array<Transform>,
-  subschema: SubschemaConfig
+  subschemaConfig?: SubschemaConfig,
+  transforms?: Array<Transform>,
+  transformedSchema?: GraphQLSchema
 ): GraphQLSchema {
-  return transforms.reduce(
+  let schemaTransforms: Array<Transform> = [];
+
+  if (subschemaConfig?.transforms != null) {
+    schemaTransforms = schemaTransforms.concat(subschemaConfig.transforms);
+  }
+
+  if (transforms) {
+    schemaTransforms = schemaTransforms.concat(transforms);
+  }
+
+  return schemaTransforms.reduce(
     (schema: GraphQLSchema, transform: Transform) =>
-      transform.transformSchema != null ? transform.transformSchema(cloneSchema(schema), subschema) : schema,
+      transform.transformSchema != null
+        ? transform.transformSchema(cloneSchema(schema), subschemaConfig, transforms, transformedSchema)
+        : schema,
     originalWrappingSchema
   );
 }
diff --git a/packages/delegate/src/types.ts b/packages/delegate/src/types.ts
@@ -23,7 +23,9 @@ import { OBJECT_SUBSCHEMA_SYMBOL, FIELD_SUBSCHEMA_MAP_SYMBOL, UNPATHED_ERRORS_SY
 
 export type SchemaTransform = (
   originalWrappingSchema: GraphQLSchema,
-  subschemaConfig?: SubschemaConfig
+  subschemaConfig?: SubschemaConfig,
+  transforms?: Array<Transform>,
+  transformedSchema?: GraphQLSchema
 ) => GraphQLSchema;
 export type RequestTransform<T = Record<string, any>> = (
   originalRequest: Request,

diff --git a/packages/stitch/tests/alternateStitchSchemas.test.ts b/packages/stitch/tests/alternateStitchSchemas.test.ts
@@ -1176,6 +1176,7 @@ describe('schema transformation with extraction of nested fields', () => {
       },
     });
   });
+
 });
 
 describe('HoistField transform', () => {
@@ -1270,6 +1271,23 @@ describe('HoistField transform', () => {
 
     expect(result).toEqual(expectedResult);
   });
+
+  test('should work to hoist fields to new root fields', async () => {
+    const wrappedSchema = wrapSchema({
+      schema,
+      transforms: [new HoistField('Query', ['query', 'inner', 'test'], 'hoisted'), new PruneSchema({})],
+    })
+
+    const result = await graphql(wrappedSchema, '{ hoisted }');
+
+    const expectedResult = {
+      data: {
+        hoisted: 'test',
+      },
+    };
+
+    expect(result).toEqual(expectedResult);
+  });
 });
 
 describe('schema transformation with wrapping of object fields', () => {

diff --git a/packages/wrap/src/generateProxyingResolvers.ts b/packages/wrap/src/generateProxyingResolvers.ts
@@ -20,27 +20,19 @@ export function generateProxyingResolvers(
   transforms: Array<Transform>
 ): Record<string, Record<string, GraphQLFieldResolver<any, any>>> {
   let targetSchema: GraphQLSchema;
-  let schemaTransforms: Array<Transform> = [];
   let createProxyingResolver: CreateProxyingResolverFn;
   let subschemaConfig: SubschemaConfig;
 
   if (isSubschemaConfig(subschemaOrSubschemaConfig)) {
     targetSchema = subschemaOrSubschemaConfig.schema;
     subschemaConfig = subschemaOrSubschemaConfig;
     createProxyingResolver = subschemaOrSubschemaConfig.createProxyingResolver ?? defaultCreateProxyingResolver;
-    if (subschemaOrSubschemaConfig.transforms != null) {
-      schemaTransforms = schemaTransforms.concat(subschemaOrSubschemaConfig.transforms);
-    }
   } else {
     targetSchema = subschemaOrSubschemaConfig;
     createProxyingResolver = defaultCreateProxyingResolver;
   }
 
-  if (transforms != null) {
-    schemaTransforms = schemaTransforms.concat(transforms);
-  }
-
-  const transformedSchema = applySchemaTransforms(targetSchema, schemaTransforms, subschemaConfig);
+  const transformedSchema = applySchemaTransforms(targetSchema, subschemaConfig, transforms);
 
   const operationTypes: Record<Operation, GraphQLObjectType> = {
     query: targetSchema.getQueryType(),

diff --git a/packages/wrap/src/transforms/FilterInputObjectFields.ts b/packages/wrap/src/transforms/FilterInputObjectFields.ts
@@ -20,8 +20,13 @@ export default class FilterInputObjectFields implements Transform {
     );
   }
 
-  public transformSchema(originalWrappingSchema: GraphQLSchema, subschemaConfig?: SubschemaConfig): GraphQLSchema {
-    return this.transformer.transformSchema(originalWrappingSchema, subschemaConfig);
+  public transformSchema(
+    originalWrappingSchema: GraphQLSchema,
+    subschemaConfig?: SubschemaConfig,
+    transforms?: Array<Transform>,
+    transformedSchema?: GraphQLSchema
+  ): GraphQLSchema {
+    return this.transformer.transformSchema(originalWrappingSchema, subschemaConfig, transforms, transformedSchema);
   }
 
   public transformRequest(

diff --git a/packages/wrap/src/transforms/FilterInterfaceFields.ts b/packages/wrap/src/transforms/FilterInterfaceFields.ts
@@ -16,7 +16,12 @@ export default class FilterInterfaceFields implements Transform {
     );
   }
 
-  public transformSchema(originalWrappingSchema: GraphQLSchema, subschemaConfig?: SubschemaConfig): GraphQLSchema {
-    return this.transformer.transformSchema(originalWrappingSchema, subschemaConfig);
+  public transformSchema(
+    originalWrappingSchema: GraphQLSchema,
+    subschemaConfig?: SubschemaConfig,
+    transforms?: Array<Transform>,
+    transformedSchema?: GraphQLSchema
+  ): GraphQLSchema {
+    return this.transformer.transformSchema(originalWrappingSchema, subschemaConfig, transforms, transformedSchema);
   }
 }
diff --git a/packages/wrap/src/transforms/FilterObjectFieldDirectives.ts b/packages/wrap/src/transforms/FilterObjectFieldDirectives.ts
@@ -13,7 +13,12 @@ export default class FilterObjectFieldDirectives implements Transform {
     this.filter = filter;
   }
 
-  public transformSchema(originalWrappingSchema: GraphQLSchema, _subschemaConfig?: SubschemaConfig): GraphQLSchema {
+  public transformSchema(
+    originalWrappingSchema: GraphQLSchema,
+    subschemaConfig?: SubschemaConfig,
+    transforms?: Array<Transform>,
+    transformedSchema?: GraphQLSchema
+  ): GraphQLSchema {
     const transformer = new TransformObjectFields(
       (_typeName: string, _fieldName: string, fieldConfig: GraphQLFieldConfig<any, any>) => {
         const keepDirectives = fieldConfig.astNode.directives.filter(dir => {
@@ -35,6 +40,6 @@ export default class FilterObjectFieldDirectives implements Transform {
       }
     );
 
-    return transformer.transformSchema(originalWrappingSchema);
+    return transformer.transformSchema(originalWrappingSchema, subschemaConfig, transforms, transformedSchema);
   }
 }
diff --git a/packages/wrap/src/transforms/FilterObjectFields.ts b/packages/wrap/src/transforms/FilterObjectFields.ts
@@ -16,7 +16,12 @@ export default class FilterObjectFields implements Transform {
     );
   }
 
-  public transformSchema(originalWrappingSchema: GraphQLSchema, subschemaConfig?: SubschemaConfig): GraphQLSchema {
-    return this.transformer.transformSchema(originalWrappingSchema, subschemaConfig);
+  public transformSchema(
+    originalWrappingSchema: GraphQLSchema,
+    subschemaConfig?: SubschemaConfig,
+    transforms?: Array<Transform>,
+    transformedSchema?: GraphQLSchema
+  ): GraphQLSchema {
+    return this.transformer.transformSchema(originalWrappingSchema, subschemaConfig, transforms, transformedSchema);
   }
 }
diff --git a/packages/wrap/src/transforms/FilterRootFields.ts b/packages/wrap/src/transforms/FilterRootFields.ts
@@ -25,7 +25,12 @@ export default class FilterRootFields implements Transform {
     );
   }
 
-  public transformSchema(originalWrappingSchema: GraphQLSchema, subschemaConfig?: SubschemaConfig): GraphQLSchema {
-    return this.transformer.transformSchema(originalWrappingSchema, subschemaConfig);
+  public transformSchema(
+    originalWrappingSchema: GraphQLSchema,
+    subschemaConfig?: SubschemaConfig,
+    transforms?: Array<Transform>,
+    transformedSchema?: GraphQLSchema
+  ): GraphQLSchema {
+    return this.transformer.transformSchema(originalWrappingSchema, subschemaConfig, transforms, transformedSchema);
   }
 }
diff --git a/packages/wrap/src/transforms/FilterTypes.ts b/packages/wrap/src/transforms/FilterTypes.ts
@@ -2,7 +2,7 @@ import { GraphQLSchema, GraphQLNamedType } from 'graphql';
 
 import { mapSchema, MapperKind } from '@graphql-tools/utils';
 
-import { Transform } from '@graphql-tools/delegate';
+import { SubschemaConfig, Transform } from '@graphql-tools/delegate';
 
 export default class FilterTypes implements Transform {
   private readonly filter: (type: GraphQLNamedType) => boolean;
@@ -11,8 +11,13 @@ export default class FilterTypes implements Transform {
     this.filter = filter;
   }
 
-  public transformSchema(schema: GraphQLSchema): GraphQLSchema {
-    return mapSchema(schema, {
+  public transformSchema(
+    originalWrappingSchema: GraphQLSchema,
+    _subschemaConfig?: SubschemaConfig,
+    _transforms?: Array<Transform>,
+    _transformedSchema?: GraphQLSchema
+  ): GraphQLSchema {
+    return mapSchema(originalWrappingSchema, {
       [MapperKind.TYPE]: (type: GraphQLNamedType) => {
         if (this.filter(type)) {
           return undefined;

diff --git a/packages/wrap/src/transforms/HoistField.ts b/packages/wrap/src/transforms/HoistField.ts
@@ -6,11 +6,14 @@ import {
   Kind,
   GraphQLError,
   GraphQLArgument,
+  GraphQLFieldConfig,
 } from 'graphql';
 
 import { appendObjectFields, removeObjectFields, Request, ExecutionResult, relocatedError } from '@graphql-tools/utils';
 
-import { Transform, defaultMergedResolver, DelegationContext } from '@graphql-tools/delegate';
+import { Transform, defaultMergedResolver, DelegationContext, SubschemaConfig } from '@graphql-tools/delegate';
+
+import { defaultCreateProxyingResolver } from '../generateProxyingResolvers';
 
 import MapFields from './MapFields';
 
@@ -61,7 +64,12 @@ export default class HoistField implements Transform {
     this.argLevels = argLevels;
   }
 
-  public transformSchema(schema: GraphQLSchema): GraphQLSchema {
+  public transformSchema(
+    originalWrappingSchema: GraphQLSchema,
+    subschemaConfig: SubschemaConfig,
+    transforms: Array<Transform>,
+    transformedSchema: GraphQLSchema
+  ): GraphQLSchema {
     const argsMap: Record<string, GraphQLArgument> = Object.create(null);
     const innerType: GraphQLObjectType = this.pathToField.reduce((acc, pathSegment, index) => {
       const field = acc.getFields()[pathSegment];
@@ -72,21 +80,38 @@ export default class HoistField implements Transform {
         }
       });
       return getNullableType(field.type) as GraphQLObjectType;
-    }, schema.getType(this.typeName) as GraphQLObjectType);
+    }, originalWrappingSchema.getType(this.typeName) as GraphQLObjectType);
 
     let [newSchema, targetFieldConfigMap] = removeObjectFields(
-      schema,
+      originalWrappingSchema,
       innerType.name,
       fieldName => fieldName === this.oldFieldName
     );
 
     const targetField = targetFieldConfigMap[this.oldFieldName];
 
-    const newTargetField = {
-      ...targetField,
-      resolve: defaultMergedResolver,
-    };
-
+    const hoistingToRootField =
+      this.typeName === originalWrappingSchema.getQueryType()?.name || originalWrappingSchema.getMutationType()?.name;
+
+    let newTargetField: GraphQLFieldConfig<any, any>;
+    if (hoistingToRootField) {
+      const createProxyingResolver = subschemaConfig.createProxyingResolver ?? defaultCreateProxyingResolver;
+      newTargetField = {
+        ...targetField,
+        resolve: createProxyingResolver({
+          schema: subschemaConfig,
+          transforms,
+          transformedSchema,
+          operation: this.typeName === originalWrappingSchema.getQueryType().name ? 'query' : 'mutation',
+          fieldName: this.newFieldName,
+        }),
+      };
+    } else {
+      newTargetField = {
+        ...targetField,
+        resolve: defaultMergedResolver,
+      };
+    }
     const level = this.pathToField.length;
 
     Object.keys(targetField.args).forEach(argName => {

diff --git a/packages/wrap/src/transforms/MapFields.ts b/packages/wrap/src/transforms/MapFields.ts
@@ -54,8 +54,13 @@ export default class MapFields implements Transform {
     );
   }
 
-  public transformSchema(originalWrappingSchema: GraphQLSchema, subschemaConfig?: SubschemaConfig): GraphQLSchema {
-    return this.transformer.transformSchema(originalWrappingSchema, subschemaConfig);
+  public transformSchema(
+    originalWrappingSchema: GraphQLSchema,
+    subschemaConfig?: SubschemaConfig,
+    transforms?: Array<Transform>,
+    transformedSchema?: GraphQLSchema
+  ): GraphQLSchema {
+    return this.transformer.transformSchema(originalWrappingSchema, subschemaConfig, transforms, transformedSchema);
   }
 
   public transformRequest(

diff --git a/packages/wrap/src/transforms/MapLeafValues.ts b/packages/wrap/src/transforms/MapLeafValues.ts
@@ -44,7 +44,12 @@ export default class MapLeafValues implements Transform<MapLeafValuesTransformat
     this.resultVisitorMap = Object.create(null);
   }
 
-  public transformSchema(originalWrappingSchema: GraphQLSchema, _subschemaConfig: SubschemaConfig): GraphQLSchema {
+  public transformSchema(
+    originalWrappingSchema: GraphQLSchema,
+    _subschemaConfig: SubschemaConfig,
+    _transforms?: Array<Transform>,
+    _transformedSchema?: GraphQLSchema
+  ): GraphQLSchema {
     this.originalWrappingSchema = originalWrappingSchema;
     const typeMap = originalWrappingSchema.getTypeMap();
     Object.keys(typeMap).forEach(typeName => {

diff --git a/packages/wrap/src/transforms/PruneSchema.ts b/packages/wrap/src/transforms/PruneSchema.ts
@@ -2,7 +2,7 @@ import { GraphQLSchema } from 'graphql';
 
 import { PruneSchemaOptions, pruneSchema } from '@graphql-tools/utils';
 
-import { Transform } from '@graphql-tools/delegate';
+import { SubschemaConfig, Transform } from '@graphql-tools/delegate';
 
 export default class PruneTypes implements Transform {
   private readonly options: PruneSchemaOptions;
@@ -11,7 +11,12 @@ export default class PruneTypes implements Transform {
     this.options = options;
   }
 
-  public transformSchema(schema: GraphQLSchema): GraphQLSchema {
-    return pruneSchema(schema, this.options);
+  public transformSchema(
+    originalWrappingSchema: GraphQLSchema,
+    _subschemaConfig?: SubschemaConfig,
+    _transforms?: Array<Transform>,
+    _transformedSchema?: GraphQLSchema
+  ): GraphQLSchema {
+    return pruneSchema(originalWrappingSchema, this.options);
   }
 }
diff --git a/packages/wrap/src/transforms/RemoveObjectFieldDeprecations.ts b/packages/wrap/src/transforms/RemoveObjectFieldDeprecations.ts
@@ -27,10 +27,17 @@ export default class RemoveObjectFieldDeprecations implements Transform {
     );
   }
 
-  public transformSchema(originalWrappingSchema: GraphQLSchema, subschemaConfig?: SubschemaConfig): GraphQLSchema {
+  public transformSchema(
+    originalWrappingSchema: GraphQLSchema,
+    subschemaConfig?: SubschemaConfig,
+    transforms?: Array<Transform>,
+    transformedSchema?: GraphQLSchema
+  ): GraphQLSchema {
     return this.removeDeprecations.transformSchema(
       this.removeDirectives.transformSchema(originalWrappingSchema, subschemaConfig),
-      subschemaConfig
+      subschemaConfig,
+      transforms,
+      transformedSchema
     );
   }
 }
diff --git a/packages/wrap/src/transforms/RemoveObjectFieldDirectives.ts b/packages/wrap/src/transforms/RemoveObjectFieldDirectives.ts
@@ -15,7 +15,12 @@ export default class RemoveObjectFieldDirectives implements Transform {
     });
   }
 
-  public transformSchema(originalWrappingSchema: GraphQLSchema, subschemaConfig?: SubschemaConfig): GraphQLSchema {
-    return this.transformer.transformSchema(originalWrappingSchema, subschemaConfig);
+  public transformSchema(
+    originalWrappingSchema: GraphQLSchema,
+    subschemaConfig?: SubschemaConfig,
+    transforms?: Array<Transform>,
+    transformedSchema?: GraphQLSchema
+  ): GraphQLSchema {
+    return this.transformer.transformSchema(originalWrappingSchema, subschemaConfig, transforms, transformedSchema);
   }
 }