Added hoist field transform package + docs

.changeset/perfect-zebras-rest.md

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+---
+'@graphql-mesh/transform-hoist-field': minor
+'@graphql-mesh/types': patch
+'@graphql-mesh/website': patch
+---
+
+Added @graphql-mesh/transform-hoist-field package

packages/transforms/hoist-field/package.json

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+{
+  "name": "@graphql-mesh/transform-hoist-field",
+  "version": "0.0.0",
+  "sideEffects": false,
+  "main": "dist/index.js",
+  "module": "dist/index.mjs",
+  "typings": "dist/index.d.ts",
+  "typescript": {
+    "definition": "dist/index.d.ts"
+  },
+  "exports": {
+    ".": {
+      "require": "./dist/index.js",
+      "import": "./dist/index.mjs"
+    },
+    "./*": {
+      "require": "./dist/*.js",
+      "import": "./dist/*.mjs"
+    }
+  },
+  "license": "MIT",
+  "peerDependencies": {
+    "graphql": "*"
+  },
+  "dependencies": {
+    "@graphql-mesh/types": "0.68.1",
+    "@graphql-mesh/utils": "0.31.0",
+    "@graphql-tools/delegate": "8.5.4",
+    "@graphql-tools/wrap": "8.4.6",
+    "@graphql-tools/utils": "8.6.3",
+    "@graphql-mesh/cache-inmemory-lru": "0.6.3"
+  },
+  "publishConfig": {
+    "access": "public",
+    "directory": "dist"
+  }
+}

packages/transforms/hoist-field/src/index.ts

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+import { MeshTransform, MeshTransformOptions, YamlConfig } from '@graphql-mesh/types';
+import { applyRequestTransforms, applyResultTransforms, applySchemaTransforms } from '@graphql-mesh/utils';
+import { DelegationContext, SubschemaConfig, Transform } from '@graphql-tools/delegate';
+import { ExecutionRequest, ExecutionResult } from '@graphql-tools/utils';
+import { HoistField } from '@graphql-tools/wrap';
+import { GraphQLSchema } from 'graphql';
+
+type HoistFieldCtorPathConfigItem = ConstructorParameters<typeof HoistField>[1][0];
+type HoistFieldTransformFieldPathConfig = YamlConfig.HoistFieldTransformConfig['pathConfig'][0];
+
+export default class MeshHoistField implements MeshTransform {
+  noWrap = false;
+  private transforms: Transform[];
+
+  constructor({ config }: MeshTransformOptions<YamlConfig.HoistFieldTransformConfig[]>) {
+    this.transforms = config.map(({ typeName, pathConfig, newFieldName, alias, filterArgsInPath = false }) => {
+      const processedPathConfig = pathConfig.map(config => this.getPathConfigItem(config, filterArgsInPath));
+      return new HoistField(typeName, processedPathConfig, newFieldName, alias);
+    });
+  }
+
+  private getPathConfigItem(
+    pathConfigItemFromConfig: HoistFieldTransformFieldPathConfig,
+    filterArgsInPath: boolean
+  ): HoistFieldCtorPathConfigItem {
+    if (typeof pathConfigItemFromConfig === 'string') {
+      const pathConfigItem: HoistFieldCtorPathConfigItem = {
+        fieldName: pathConfigItemFromConfig,
+        argFilter: () => filterArgsValue(filterArgsInPath),
+      };
+
+      return pathConfigItem;
+    }
+
+    if (!pathConfigItemFromConfig.fieldName) {
+      throw new Error(`Field name is required in pathConfig item`);
+    }
+
+    if (!pathConfigItemFromConfig.filterArgs) {
+      throw new Error(`FilterArgs is required in pathConfig item`);
+    }
+
+    const filterArgsDict = (pathConfigItemFromConfig.filterArgs || []).reduce((prev, argName) => {
+      prev[argName] = true;
+      return prev;
+    }, {});
+
+    const pathConfigItem: HoistFieldCtorPathConfigItem = {
+      fieldName: pathConfigItemFromConfig.fieldName,
+      argFilter: arg => {
+        return filterArgsValue(filterArgsDict[arg.name]);
+      },
+    };
+
+    return pathConfigItem;
+  }
+
+  transformSchema(
+    originalWrappingSchema: GraphQLSchema,
+    subschemaConfig: SubschemaConfig,
+    transformedSchema?: GraphQLSchema
+  ) {
+    return applySchemaTransforms(originalWrappingSchema, subschemaConfig, transformedSchema, this.transforms);
+  }
+
+  transformRequest(
+    originalRequest: ExecutionRequest,
+    delegationContext: DelegationContext,
+    transformationContext: Record<string, any>
+  ) {
+    return applyRequestTransforms(originalRequest, delegationContext, transformationContext, this.transforms);
+  }
+
+  transformResult(originalResult: ExecutionResult, delegationContext: DelegationContext, transformationContext: any) {
+    return applyResultTransforms(originalResult, delegationContext, transformationContext, this.transforms);
+  }
+}
+
+// The argFilters in HoistField seem to work more like argIncludes, hence the value needs to be negated
+// https://github.com/ardatan/graphql-tools/blob/af266974bf02967e0675187e9bea0391fd7fe0cf/packages/wrap/src/transforms/HoistField.ts#L44
+function filterArgsValue(filter: boolean) {
+  return !filter;
+}

packages/transforms/hoist-field/test/__snapshots__/transform.spec.ts.snap

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+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`hoist should hoist field and filter args with global flag 1`] = `
+"type Query {
+  users: [User!]!
+}
+
+type UserSearchResult {
+  page: Int!
+}
+
+type User {
+  id: ID!
+  name: String!
+}"
+`;
+
+exports[`hoist should hoist field and filter individual args via pathConfig 1`] = `
+"type Query {
+  users(page: Int): [User!]!
+}
+
+type UserSearchResult {
+  page: Int!
+}
+
+type User {
+  id: ID!
+  name: String!
+}"
+`;
+
+exports[`hoist should hoist field and filter individual args via pathConfig independent of global flag 1`] = `
+"type Query {
+  users(page: Int): [User!]!
+}
+
+type UserSearchResult {
+  page: Int!
+}
+
+type User {
+  id: ID!
+  name: String!
+}"
+`;
+
+exports[`hoist should hoist field with mixed pathConfig array 1`] = `
+"type Query {
+  users(limit: Int!, page: Int): [User!]!
+}
+
+type UserSearchResult {
+  page: Int!
+}
+
+type User {
+  id: ID!
+  name: String!
+}"
+`;
+
+exports[`hoist should hoist field with string pathConfig array 1`] = `
+"type Query {
+  users(limit: Int!, page: Int): [User!]!
+}
+
+type UserSearchResult {
+  page: Int!
+}
+
+type User {
+  id: ID!
+  name: String!
+}"
+`;