From cbbfb99e747cea70928d51b4a5f184dfe485e74b Mon Sep 17 00:00:00 2001
From: Eivind Fjeldstad <eivind.fjeldstad@gmail.com>
Date: Fri, 28 Feb 2014 00:28:07 +0100
Subject: [PATCH] initial commit

---
 .gitignore   |  1 +
 Makefile     |  5 +++
 Readme.md    | 31 +++++++++++++++++++
 index.js     | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 package.json | 22 ++++++++++++++
 test.js      | 36 ++++++++++++++++++++++
 6 files changed, 181 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 Readme.md
 create mode 100644 index.js
 create mode 100644 package.json
 create mode 100644 test.js

diff --git a/.gitignore b/.gitignore
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--- /dev/null
+++ b/.gitignore
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+node_modules
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diff --git a/Makefile b/Makefile
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--- /dev/null
+++ b/Makefile
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+test:
+	@./node_modules/.bin/mocha \
+		--reporter spec
+
+.PHONY: test
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diff --git a/Readme.md b/Readme.md
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index 0000000..1820183
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+++ b/Readme.md
@@ -0,0 +1,31 @@
+
+# mongo-query
+
+Get object diff as a MongoDB update query.
+
+Useful for reducing the size of your queries.
+Uses (cloudup/mongo-eql)[https://github.com/cloudup/mongo-eql] to compare values and
+and (cloudup/mongo-minify)[https://github.com/cloudup/mongo-minify] to optionally filter
+out disallowed operations.
+
+## Installation
+
+    $ npm install mongo-update
+
+## Example
+
+```js
+var update = require('mongo-update');
+var query = update({ a: 'hello' }, { b: 'world' });
+// => { $set: { b: 'hello' }, $unset: { a: 1 }}
+```
+
+Or with a filter (see (cloudup/mongo-minify)[https://github.com/cloudup/mongo-minify] for more examples)
+```js
+var query = update({ a: 1, b: 2 }, { a: 2, b: 3 }, { a: 1 });
+// => { $set: { a: 2 }}
+```
+
+## License
+
+  MIT
diff --git a/index.js b/index.js
new file mode 100644
index 0000000..8e2df97
--- /dev/null
+++ b/index.js
@@ -0,0 +1,86 @@
+var minify = require('mongo-minify');
+var is = require('component-type');
+var eql = require('mongo-eql');
+
+/**
+ * Get object diff as a MongoDB update query
+ *
+ * @param {Object} a
+ * @param {Object} b
+ * @param {Object} [filter]
+ * @return {Object}
+ * @api public
+ */
+
+module.exports = function (a, b, filter) {
+  var ret = {};
+  filter = filter || {};
+  diff(a, b, ret);
+  return minify(ret, filter);
+}
+
+/**
+ * Traverse both objects and put ops on the `query` object
+ */
+
+function diff (a, b, query, prefix) {
+  // find removed keys
+  for (var key in a) {
+    var path = join(key, prefix);
+    if (b[key] == null) unset(query, path);
+  }
+  
+  // find changed keys
+  for (var key in b) {
+    var path = join(key, prefix);
+    
+    // removed
+    if (b[key] == null) continue;
+    
+    // no change
+    if (eql(a[key], b[key])) continue;
+    
+    // new type
+    if (is(a[key]) != is(b[key])) {
+      set(query, path, b[key]);
+      continue;
+    }
+    
+    // object
+    if (is(a[key]) == 'object') {
+      diff(a[key], b[key], query, path);
+      continue;
+    }
+    
+    // default
+    set(query, path, b[key]);
+  }
+}
+
+/**
+ * $set `field` to `val`
+ */
+
+function set (query, field, val) {
+  query['$set'] = query['$set'] || {};
+  query['$set'][field] = val;
+}
+
+/**
+ * $unset `field`
+ */
+
+function unset (query, field) {
+  query['$unset'] = query['$unset'] || {};
+  query['$unset'][field] = 1;
+};
+
+/**
+ * Join `key` with `prefix` using dot-notation
+ */
+
+function join (key, prefix) {
+  return prefix
+    ? prefix + '.' + key
+    : key;
+}
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diff --git a/package.json b/package.json
new file mode 100644
index 0000000..684c034
--- /dev/null
+++ b/package.json
@@ -0,0 +1,22 @@
+{
+  "name": "mongo-update",
+  "version": "0.0.1",
+  "description": "Get object diff as a MongoDB update query",
+  "main": "index.js",
+  "scripts": {
+    "test": "make test"
+  },
+  "license": "MIT",
+  "dependencies": {
+    "component-type": "~1.0.0",
+    "mongo-eql": "~0.1.0",
+    "mongo-minify": "~0.1.1"
+  },
+  "devDependencies": {
+    "mocha": "~1.17.1"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/eivindfjeldstad/mongo-update.git"
+  }
+}
diff --git a/test.js b/test.js
new file mode 100644
index 0000000..c6e9420
--- /dev/null
+++ b/test.js
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+var assert = require('assert');
+var diff = require('./');
+
+describe('query()', function () {
+  it('should $set modified keys', function () {
+    var query = diff({ a: 1 }, { a: 2 });
+    assert(query.$set.a == 2);
+    assert(!('$unset' in query));
+  });
+  
+  it('should $unset null-ish keys', function () {
+    var query = diff({ a: 1 }, { a: null });
+    assert(query.$unset.a == 1);
+    assert(!('$set' in query));
+  });
+  
+  it('should work with nested keys', function () {
+    var query = diff({ a: { b: 1, c: 2 }}, { a: { b: 2 }});
+    assert(query.$set['a.b'] == 2);
+    assert(query.$unset['a.c'] == 1);
+  });
+  
+  describe('when given a filter', function () {
+    it('should minify the query', function () {
+      var query = diff({ a: 1, b: 2 }, { a: 2, b: 3 }, { a: 1 });
+      assert(query.$set.a == 2);
+      assert(!('b' in query.$set));
+    });
+    
+    it('should work with nested keys', function () {
+      var query = diff({ a: { b: 1, c: 2 }}, { a: { b: 2 }}, { 'a.b': 1 });
+      assert(query.$set['a.b'] == 2);
+      assert(!('$unset' in query));
+    });
+  });
+})
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