feat: "dynamicDefaults" keyword

Author: epoberezkin

README.md

@@ -7,6 +7,20 @@ Custom JSON-Schema keywords for [ajv](https://github.com/epoberezkin/ajv) valida
 [![Coverage Status](https://coveralls.io/repos/github/epoberezkin/ajv-keywords/badge.svg?branch=master)](https://coveralls.io/github/epoberezkin/ajv-keywords?branch=master)
 
 
+## Contents
+
+- [Install](#install)
+- [Usage](#usage)
+- [Keywords](#keywords)
+  - [typeof](#typeof)
+  - [instanceof](#instanceof)
+  - [range and exclusiveRange](#range-and-exclusiverange)
+  - [propertyNames](#propertynames)
+  - [regexp](#regexp)
+  - [dynamicDefaults](#dynamicdefaults)
+- [License](#license)
+
+
 ## Install
 
 ```
@@ -168,6 +182,117 @@ var invalidData = {
 ```
 
 
+### `dynamicDefaults`
+
+This keyword allows to assign dynamic defaults to properties, such as timestamps, unique IDs etc.
+
+This keyword only works if `useDefaults` options is used and not inside `anyOf` keywrods etc., in the same way as [default keyword treated by Ajv](https://github.com/epoberezkin/ajv#assigning-defaults).
+
+The keyword should be added on the object level. Its value should be an object with each property corresponding to a property name, in the same way as in standard `properties` keyword. The value of each property can be:
+
+- an identifier of default function (a string)
+- an object with properties `func` (an identifier) and `args` (an object with parameters that will be passed to this function during schema compilation - see examples).
+
+The properties used in `dynamicDefaults` should not be added to `required` keyword (or validation will fail), because unlike `default` this keyword is processed after validation.
+
+There are several predefined dynamic default functions:
+
+- `"timestamp"` - current timestamp in milliseconds
+- `"datetime"' - current date and time as string (ISO, valid according to `date-time` format)
+- `"date"' - current date as string (ISO, valid according to `date` format)
+- `"time"` - current time as string (ISO, valid according to `time` format)
+- `"random"` - pseudo-random number in [0, 1) interval
+- `"randomint"` - pseudo-random integer number. If string is used as a property value, the function will randomly return 0 or 1. If object `{func: 'randomint', max: N}` is used then the default will be an integer number in [0, N) interval.
+- `"seq"` - sequential integer number starting from 0. If string is used as a property value, the default sequence will be used. If object `{func: 'seq', name: 'foo'}` is used then the sequence with name `"foo"` will be used. Sequences are global, even if different ajv instances are used.
+
+```javascript
+var schema = {
+  type: 'object',
+  dynamicDefaults: {
+    ts: 'datetime',
+    r: { func: 'randomint', max: 100 },
+    id: { func: 'seq', name: 'id' }
+  },
+  properties: {
+    ts: {
+      type: 'string',
+      format: 'datetime'
+    },
+    r: {
+      type: 'integer',
+      minimum: 0,
+      maximum: 100,
+      exclusiveMaximum: true
+    },
+    id: {
+      type: 'integer',
+      minimum: 0
+    }
+  }
+};
+
+var data = {};
+ajv.validate(data); // true
+data; // { ts: '2016-12-01T22:07:28.829Z', r: 25, id: 0 }
+
+var data1 = {};
+ajv.validate(data1); // true
+data1; // { ts: '2016-12-01T22:07:29.832Z', r: 68, id: 1 }
+
+ajv.validate(data1); // true
+data1; // didn't change, as all properties were defined
+```
+
+You can add your own dynamic default function to be recognised by this keyword:
+
+```javascript
+var uuid = require('uuid');
+
+function uuidV4() { return uuid.v4(); }
+
+var definition = require('ajv-keywords').get('dynamicDefaults').definition;
+// or require('ajv-keywords/keywords/dynamicDefaults').definition;
+definition.DEFAULTS.uuid = uuidV4;
+
+var schema = {
+  dynamicDefaults: { id: 'uuid' },
+  properties: { id: { type: 'string', format: 'uuid' } }
+};
+
+var data = {};
+ajv.validate(schema, data); // true
+data; // { id: 'a1183fbe-697b-4030-9bcc-cfeb282a9150' };
+
+var data1 = {};
+ajv.validate(schema, data1); // true
+data1; // { id: '5b008de7-1669-467a-a5c6-70fa244d7209' }
+```
+
+You also can define dynamic default that accepts parameters, e.g. version of uuid:
+
+```javascript
+var uuid = require('uuid');
+
+function getUuid(args) {
+  var version = 'v' + (arvs && args.v || 4);
+  return function() {
+    return uuid[version]();
+  };
+}
+
+var definition = require('ajv-keywords').get('dynamicDefaults').definition;
+definition.DEFAULTS.uuid = getUuid;
+
+var schema = {
+  dynamicDefaults: {
+    id1: 'uuid', // v4
+    id2: { func: 'uuid', v: 4 }, // v4
+    id3: { func: 'uuid', v: 1 } // v1
+  }
+};
+```
+
+
 ## License
 
 [MIT](https://github.com/JSONScript/ajv-keywords/blob/master/LICENSE)

keywords/dynamicDefaults.js

@@ -0,0 +1,67 @@
+'use strict';
+
+var sequences = {};
+
+var DEFAULTS = {
+  timestamp: function() { return Date.now(); },
+  datetime: function() { return (new Date).toISOString(); },
+  date: function() { return (new Date).toISOString().slice(0, 10); },
+  time: function() { return (new Date).toISOString().slice(11); },
+  random: function() { return Math.random(); },
+  randomint: function (args) {
+    var limit = args && args.max || 2;
+    return function() { return Math.floor(Math.random() * limit); };
+  },
+  seq: function (args) {
+    var name = args && args.name || '';
+    sequences[name] = sequences[name] || 0;
+    return function() { return sequences[name]++; };
+  }
+};
+
+module.exports = function defFunc(ajv) {
+  defFunc.definition = {
+    compile: function (schema, parentSchema, it) {
+      var funcs = {};
+
+      for (var key in schema) {
+        var d = schema[key];
+        var func = getDefault(typeof d == 'string' ? d : d.func);
+        funcs[key] = func.length ? func(d.args) : func;
+      }
+
+      return it.opts.useDefaults && !it.compositeRule
+              ? assignDefaults
+              : noop;
+
+      function assignDefaults(data) {
+        for (var prop in schema)
+          if (data[prop] === undefined) data[prop] = funcs[prop]();
+        return true;
+      }
+
+      function noop() { return true; }
+    },
+    DEFAULTS: DEFAULTS,
+    metaSchema: {
+      type: 'object',
+      additionalProperties: {
+        type: ['string', 'object'],
+        additionalProperties: false,
+        required: ['func', 'args'],
+        properties: {
+          func: { type: 'string' },
+          args: { type: 'object' }
+        }
+      }
+    }
+  };
+
+  ajv.addKeyword('dynamicDefaults', defFunc.definition);
+
+  function getDefault(d) {
+    var def = DEFAULTS[d];
+    if (def) return def;
+    throw new Error('invalid "dynamicDefaults" keyword property value: ' + d);
+  }
+};

keywords/index.js

@@ -1,9 +1,10 @@
 'use strict';
 
 module.exports = {
-  'typeof': require('./typeof'),
   'instanceof': require('./instanceof'),
-  range: require('./range'),
   propertyNames: require('./propertyNames'),
-  regexp: require('./regexp')
+  range: require('./range'),
+  regexp: require('./regexp'),
+  'typeof': require('./typeof'),
+  dynamicDefaults: require('./dynamicDefaults')
 };

package.json

@@ -1,6 +1,6 @@
 {
   "name": "ajv-keywords",
-  "version": "1.1.1",
+  "version": "1.2.0",
   "description": "Custom JSON-Schema keywords for ajv validator",
   "main": "index.js",
   "scripts": {
@@ -25,16 +25,17 @@
   },
   "homepage": "https://github.com/epoberezkin/ajv-keywords#readme",
   "peerDependencies": {
-    "ajv": ">=4.2.0"
+    "ajv": ">=4.9.0"
   },
   "devDependencies": {
-    "ajv": "^4.7.4",
+    "ajv": "^4.9.0",
     "ajv-pack": "^0.2.0",
     "chai": "^3.5.0",
     "coveralls": "^2.11.9",
     "eslint": "^3.6.0",
     "istanbul": "^0.4.3",
     "mocha": "^3.0.2",
-    "pre-commit": "^1.1.3"
+    "pre-commit": "^1.1.3",
+    "uuid": "^3.0.1"
   }
 }