Merge pull request #65 from yosimasu/feature/json-string-packer

Support JSONStringPacker

lib/json-string-packer.js

@@ -0,0 +1,94 @@
+// Copyright IBM Corp. 2014,2016. All Rights Reserved.
+// Node module: loopback-connector
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+'use strict';
+
+var createPromiseCallback = require('./utils').createPromiseCallback;
+
+module.exports = JSONStringPacker;
+
+var ISO_DATE_REGEXP = /^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2}(?:\.\d*))(?:Z|(\+|-)([\d|:]*))?$/;
+
+/**
+ * Create a new Packer instance that can be used to convert between JavaScript
+ * objects and a JsonString representation in a String.
+ *
+ * @param {String} encoding Buffer encoding refer to https://nodejs.org/api/buffer.html#buffer_buffers_and_character_encodings
+ */
+function JSONStringPacker(encoding) {
+  this.encoding = encoding || 'base64';
+}
+
+/**
+ * Encode the provided value to a `JsonString`.
+ *
+ * @param {*} value Any value (string, number, object)
+ * @callback {Function} cb The callback to receive the parsed result.
+ * @param {Error} err
+ * @param {Buffer} data The encoded value
+ * @promise
+ */
+JSONStringPacker.prototype.encode = function(value, cb) {
+  var encoding = this.encoding;
+
+  cb = cb || createPromiseCallback();
+  try {
+    var data = JSON.stringify(value, function(key, value) {
+      if (Buffer.isBuffer(this[key])) {
+        return {
+          type: 'Buffer',
+          data: this[key].toString(encoding),
+        };
+      } else {
+        return value;
+      }
+    });
+
+    setImmediate(function() {
+      cb(null, data);
+    });
+  } catch (err) {
+    setImmediate(function() {
+      cb(err);
+    });
+  }
+  return cb.promise;
+};
+
+/**
+ * Decode the JsonString value back to a JavaScript value.
+ * @param {String} jsonString The JsonString input.
+ * @callback {Function} cb The callback to receive the composed value.
+ * @param {Error} err
+ * @param {*} value Decoded value.
+ * @promise
+ */
+JSONStringPacker.prototype.decode = function(jsonString, cb) {
+  var encoding = this.encoding;
+
+  cb = cb || createPromiseCallback();
+  try {
+    var value = JSON.parse(jsonString, function(k, v) {
+      if (v && v.type && v.type === 'Buffer') {
+        return new Buffer(v.data, encoding);
+      }
+
+      if (ISO_DATE_REGEXP.exec(v)) {
+        return new Date(v);
+      }
+
+      return v;
+    });
+
+    setImmediate(function() {
+      cb(null, value);
+    });
+  } catch (err) {
+    setImmediate(function() {
+      cb(err);
+    });
+  }
+  return cb.promise;
+};

test/json-string-packer.test.js

@@ -0,0 +1,72 @@
+// Copyright IBM Corp. 2016. All Rights Reserved.
+// Node module: loopback-connector
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+'use strict';
+
+var JSONStringPacker = require('../lib/json-string-packer');
+var expect = require('chai').expect;
+
+describe('JSONStringPacker', function() {
+  var packer;
+
+  beforeEach(function createPacker() {
+    packer = new JSONStringPacker();
+  });
+
+  describe('encode()', function() {
+    it('supports invocation with a callback', function(done) {
+      packer.encode('a-value', done);
+    });
+  });
+
+  describe('decode()', function() {
+    it('supports invocation with a callback', function(done) {
+      packer.encode('a-value', function(err, jsonString) {
+        if (err) return done(err);
+        packer.decode(jsonString, function(err, result) {
+          if (err) return done(err);
+          expect(result).to.eql('a-value');
+          done();
+        });
+      });
+    });
+  });
+
+  describe('roundtrip', function() {
+    var TEST_CASES = {
+      String: 'a-value',
+      Object: { a: 1, b: 2 },
+      Buffer: new Buffer([1, 2, 3]),
+      Date: new Date('2016-08-03T11:53:03.470Z'),
+      Integer: 12345,
+      Float: 12.345,
+      Boolean: false,
+    };
+
+    Object.keys(TEST_CASES).forEach(function(tc) {
+      it('works for ' + tc + ' values', function() {
+        var value = TEST_CASES[tc];
+        return encodeAndDecode(value)
+          .then(function(result) {
+            expect(result).to.eql(value);
+          });
+      });
+    });
+
+    it('works for nested properties', function() {
+      return encodeAndDecode(TEST_CASES)
+        .then(function(result) {
+          expect(result).to.eql(TEST_CASES);
+        });
+    });
+
+    function encodeAndDecode(value) {
+      return packer.encode(value)
+        .then(function(binary) {
+          return packer.decode(binary);
+        });
+    }
+  });
+});