addMetaSchema method, closes #26

README.md

@@ -39,6 +39,8 @@ npm install ajv
 
 ## Usage
 
+The fastest validation call:
+
 ```
 var Ajv = require('ajv');
 var ajv = Ajv(); // options can be passed
@@ -47,7 +49,7 @@ var valid = validate(data);
 if (!valid) console.log(validate.errors);
 ```
 
-or
+or with less code
 
 ```
 // ...
@@ -68,6 +70,8 @@ if (!valid) console.log(ajv.errorsText());
 
 ajv compiles schemas to functions and caches them in all cases (using stringified schema as a key - using [json-stable-stringify](https://github.com/substack/json-stable-stringify)), so that the next time the same schema is used (not necessarily the same object instance) it won't be compiled again.
 
+The best performance is achieved when using compiled functions (there is no additional function call).
+
 
 ## Using in browser
 
@@ -159,6 +163,13 @@ Version [1.0](https://github.com/epoberezkin/ajv/tree/1.0.0) will only compile s
 By default schema is validated against meta-schema before it is compiled and if the schema does not pass validation the exception is thrown. This behaviour is controlled by `validateSchema` option.
 
 
+##### .addMetaSchema(Object schema [, String key]) -> Function
+
+Adds meta schema that can be used to validate other schemas. That function should be used instead of `addSchema` because there may be instance options that would compile a meta schema incorrectly (at the moment it is `removeAdditional` option).
+
+There is no need to explicitely add draft 4 meta schema (http://json-schema.org/draft-04/schema) - it is added by default, unless option `meta` is set to `false`. You only need to use it if you have a changed meta-schema that you want to use to validate your schemas. See `validateSchema`.
+
+
 ##### .validateSchema(Object schema) -> Boolean
 
 Validates schema. This method should be used to validate schemas rather than `validate` due to the inconsistency of `uri` format in JSON-Schema standart.

lib/ajv.js

@@ -80,7 +80,7 @@ function Ajv(opts) {
      * Adds schema to the instance.
      * @param {Object|Array} schema schema or array of schemas. If array is passed, `key` will be ignored.
      * @param {String} key Optional schema key. Can be passed to `validate` method instead of schema object or id/ref. One schema per instance can have empty `id` and `key`.
-     * @return {Function} compiled schema with method `validate` that accepts `data`.
+     * @return {Function} compiled schema function.
      */
     function addSchema(schema, key, _skipValidation) {
         if (Array.isArray(schema))
@@ -93,6 +93,22 @@ function Ajv(opts) {
     }
 
 
+    /**
+     * Add schema that will be used to validate other schemas
+     * removeAdditional option is alway set to false
+     * @param {Object} schema
+     * @param {String} key optional schema key
+     * @return {Function} compiled schema
+     */
+    function addMetaSchema(schema, key, _skipValidation) {
+        var currentRemoveAdditional = self.opts.removeAdditional;
+        self.opts.removeAdditional = false;
+        var validate = addSchema(schema, META_SCHEMA_ID, true);
+        self.opts.removeAdditional = currentRemoveAdditional;
+        return validate;
+    }
+
+
     /**
      * Validate schema
      * @param  {Object} schema schema to validate
@@ -189,12 +205,8 @@ function Ajv(opts) {
 
 
     function addInitialSchemas() {
-        if (self.opts.meta !== false) {
-            var currentRemoveAdditional = self.opts.removeAdditional;
-            self.opts.removeAdditional = false;
-            addSchema(require('./refs/json-schema-draft-04.json'), META_SCHEMA_ID, true);
-            self.opts.removeAdditional = currentRemoveAdditional;
-        }
+        if (self.opts.meta !== false)
+            addMetaSchema(require('./refs/json-schema-draft-04.json'), META_SCHEMA_ID);
 
         var optsSchemas = self.opts.schemas;
         if (!optsSchemas) return;

package.json

@@ -1,6 +1,6 @@
 {
   "name": "ajv",
-  "version": "0.6.13",
+  "version": "0.6.14",
   "description": "Another JSON Schema Validator",
   "main": "lib/ajv.js",
   "scripts": {