First

.babelrc

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+{
+  "presets": ["latest"],
+  "plugins": [
+    "syntax-flow",
+    "transform-flow-strip-types",
+    "transform-runtime"
+  ]
+}

.gitignore

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+node_modules

README.md

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+# graphql-fetch-schema
+
+Fetch a GraphQL schema from a server and write it to file
+
+## Usage
+
+```sh
+graphql-fetch-schema <url> [options]
+```
+
+### Options
+
+```
+-h, --help                output usage information
+-V, --version             output the version number
+-g, --graphql             write schema.graphql file
+-j, --json                write schema.json file
+-o, --output <directory>  write to specified directory
+```
+
+## License
+
+MIT

bin/graphql-fetch-schema

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+#!/usr/bin/env node
+require('../lib/cli')

lib/cli.js

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+'use strict';
+
+var _regenerator = require('babel-runtime/regenerator');
+
+var _regenerator2 = _interopRequireDefault(_regenerator);
+
+var _asyncToGenerator2 = require('babel-runtime/helpers/asyncToGenerator');
+
+var _asyncToGenerator3 = _interopRequireDefault(_asyncToGenerator2);
+
+var _commander = require('commander');
+
+var _commander2 = _interopRequireDefault(_commander);
+
+var _index = require('./index');
+
+var _index2 = _interopRequireDefault(_index);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+var run = function () {
+  var _ref = (0, _asyncToGenerator3.default)(_regenerator2.default.mark(function _callee(url, options) {
+    var files;
+    return _regenerator2.default.wrap(function _callee$(_context) {
+      while (1) {
+        switch (_context.prev = _context.next) {
+          case 0:
+            _context.prev = 0;
+            _context.next = 3;
+            return (0, _index2.default)(url, options);
+
+          case 3:
+            files = _context.sent;
+
+            files.forEach(function (file) {
+              console.log(file.filePath);
+            });
+            _context.next = 10;
+            break;
+
+          case 7:
+            _context.prev = 7;
+            _context.t0 = _context['catch'](0);
+
+            console.error(_context.t0);
+
+          case 10:
+          case 'end':
+            return _context.stop();
+        }
+      }
+    }, _callee, undefined, [[0, 7]]);
+  }));
+
+  return function run(_x, _x2) {
+    return _ref.apply(this, arguments);
+  };
+}();
+
+_commander2.default.version('0.1.0').usage('<url> [options]').option('-g, --graphql', 'write schema.graphql file').option('-j, --json', 'write schema.json file').option('-o, --output <directory>', 'write to specified directory').parse(process.argv);
+
+run(_commander2.default.args[0], {
+  graphql: !!_commander2.default.graphql,
+  json: !!_commander2.default.json,
+  outputPath: _commander2.default.output
+});

lib/index.js

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+'use strict';
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+
+var _regenerator = require('babel-runtime/regenerator');
+
+var _regenerator2 = _interopRequireDefault(_regenerator);
+
+var _stringify = require('babel-runtime/core-js/json/stringify');
+
+var _stringify2 = _interopRequireDefault(_stringify);
+
+var _asyncToGenerator2 = require('babel-runtime/helpers/asyncToGenerator');
+
+var _asyncToGenerator3 = _interopRequireDefault(_asyncToGenerator2);
+
+var _promise = require('babel-runtime/core-js/promise');
+
+var _promise2 = _interopRequireDefault(_promise);
+
+var _utilities = require('graphql/utilities');
+
+var _fs = require('fs');
+
+var _fs2 = _interopRequireDefault(_fs);
+
+var _nodeFetch = require('node-fetch');
+
+var _nodeFetch2 = _interopRequireDefault(_nodeFetch);
+
+var _path = require('path');
+
+var _path2 = _interopRequireDefault(_path);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+var writeFile = function writeFile(_ref) {
+  var filePath = _ref.filePath,
+      contents = _ref.contents;
+
+  return new _promise2.default(function (resolve, reject) {
+    _fs2.default.writeFile(filePath, contents, function (err) {
+      if (err) reject(err);else resolve();
+    });
+  });
+};
+
+exports.default = function () {
+  var _ref2 = (0, _asyncToGenerator3.default)(_regenerator2.default.mark(function _callee(url) {
+    var options = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : {};
+    var pathPrefix, res, schema, files;
+    return _regenerator2.default.wrap(function _callee$(_context) {
+      while (1) {
+        switch (_context.prev = _context.next) {
+          case 0:
+            // If no option is set, consider it's all
+            if (!options.graphql && !options.json) {
+              options.graphql = true;
+              options.json = true;
+            }
+            pathPrefix = options.outputPath || './';
+            _context.next = 4;
+            return (0, _nodeFetch2.default)(url, {
+              method: 'POST',
+              headers: {
+                'Accept': 'application/json',
+                'Content-Type': 'application/json'
+              },
+              body: (0, _stringify2.default)({
+                query: _utilities.introspectionQuery
+              })
+            });
+
+          case 4:
+            res = _context.sent;
+            _context.next = 7;
+            return res.json();
+
+          case 7:
+            schema = _context.sent;
+            files = [];
+
+            if (options.graphql) {
+              files.push({
+                filePath: _path2.default.resolve(pathPrefix, 'schema.graphql'),
+                contents: (0, _utilities.printSchema)((0, _utilities.buildClientSchema)(schema.data))
+              });
+            }
+            if (options.json) {
+              files.push({
+                filePath: _path2.default.resolve(pathPrefix, 'schema.json'),
+                contents: (0, _stringify2.default)(schema, null, 2)
+              });
+            }
+
+            _context.next = 13;
+            return _promise2.default.all(files.map(writeFile));
+
+          case 13:
+            return _context.abrupt('return', files);
+
+          case 14:
+          case 'end':
+            return _context.stop();
+        }
+      }
+    }, _callee, undefined);
+  }));
+
+  return function (_x, _x2) {
+    return _ref2.apply(this, arguments);
+  };
+}();

package.json

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+{
+  "name": "graphql-fetch-schema",
+  "version": "0.1.0",
+  "description": "Fetch a GraphQL schema from a server and write it to file",
+  "main": "lib/index.js",
+  "bin": {
+    "graphql-fetch-schema": "./bin/graphql-fetch-schema"
+  },
+  "scripts": {
+    "clean": "rm -rf ./lib",
+    "compile": "babel src --out-dir lib",
+    "build": "npm run clean && npm run compile",
+    "start": "npm run compile"
+  },
+  "author": "Paul Le Cam <[email protected]>",
+  "license": "MIT",
+  "dependencies": {
+    "babel-runtime": "^6.18.0",
+    "commander": "^2.9.0",
+    "graphql": "^0.7.2",
+    "node-fetch": "^1.6.3"
+  },
+  "devDependencies": {
+    "babel-cli": "^6.18.0",
+    "babel-plugin-syntax-flow": "^6.18.0",
+    "babel-plugin-transform-flow-strip-types": "^6.18.0",
+    "babel-plugin-transform-runtime": "^6.15.0",
+    "babel-preset-latest": "^6.16.0"
+  }
+}

src/cli.js

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+// @flow
+
+import program from 'commander'
+
+import fetchSchema from './index'
+
+const run = async (url: string, options: Object) => {
+  try {
+    const files = await fetchSchema(url, options)
+    files.forEach((file: Object) => {
+      console.log(file.filePath)
+    })
+  } catch (err) {
+    console.error(err)
+  }
+}
+
+program
+  .version('0.1.0')
+  .usage('<url> [options]')
+  .option('-g, --graphql', 'write schema.graphql file')
+  .option('-j, --json', 'write schema.json file')
+  .option('-o, --output <directory>', 'write to specified directory')
+  .parse(process.argv)
+
+run(program.args[0], {
+  graphql: !!program.graphql,
+  json: !!program.json,
+  outputPath: program.output,
+})

src/index.js

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+// @flow
+
+import {
+  buildClientSchema,
+  introspectionQuery,
+  printSchema,
+} from 'graphql/utilities'
+import fs from 'fs'
+import fetch from 'node-fetch'
+import path from 'path'
+
+type Options = {
+  graphql?: boolean,
+  json?: boolean,
+  outputPath?: string,
+}
+
+const writeFile = ({filePath, contents}: {filePath: string, contents: string}) => {
+  return new Promise((resolve, reject) => {
+    fs.writeFile(filePath, contents, (err) => {
+      if (err) reject(err)
+      else resolve()
+    })
+  })
+}
+
+export default async (url: string, options: Options = {}) => {
+  // If no option is set, consider it's all
+  if (!options.graphql && !options.json) {
+    options.graphql = true
+    options.json = true
+  }
+  const pathPrefix = options.outputPath || './'
+
+  const res = await fetch(url, {
+    method: 'POST',
+    headers: {
+      'Accept': 'application/json',
+      'Content-Type': 'application/json',
+    },
+    body: JSON.stringify({
+      query: introspectionQuery,
+    }),
+  })
+  const schema = await res.json()
+
+  const files = []
+  if (options.graphql) {
+    files.push({
+      filePath: path.resolve(pathPrefix, 'schema.graphql'),
+      contents: printSchema(buildClientSchema(schema.data)),
+    })
+  }
+  if (options.json) {
+    files.push({
+      filePath: path.resolve(pathPrefix, 'schema.json'),
+      contents: JSON.stringify(schema, null, 2),
+    })
+  }
+
+  await Promise.all(files.map(writeFile))
+  return files
+}