feat: anyRequired keyword, closes #85

README.md

@@ -28,6 +28,7 @@ Custom JSON-Schema keywords for [Ajv](https://github.com/epoberezkin/ajv) valida
     - [uniqueItemProperties](#uniqueitemproperties)
   - [Keywords for objects](#keywords-for-objects)
     - [allRequired](allrequired)
+    - [anyRequired](anyrequired)
     - [patternRequired](#patternrequired)
     - [prohibited](#prohibited)
     - [deepProperties](#deepproperties)
@@ -338,6 +339,28 @@ var invalidDataList = [ {}, { foo: 1 }, { bar: 2 } ];
 ```
 
 
+#### `anyRequired`
+
+This keyword allows to require the presence of any (at least one) property from the list.
+
+This keyword applies only to objects. If the data is not an object, the validation succeeds.
+
+The value of this keyword must be an array of strings, each string being a property name. For data object to be valid at least one of the properties in this array should be present in the object.
+
+```javascript
+var schema = {
+  anyRequired: ['foo', 'bar']
+};
+
+var validData = { foo: 1 };
+var alsoValidData = { foo: 1, bar: 2 };
+
+var invalidDataList = [ {}, { baz: 3 } ];
+```
+
+__Please note__: By combining `anyRequired` with `maxProperties: 1` you can achieve that exactly one property from the list is required to be present for the data object to pass validation.
+
+
 #### `patternRequired`
 
 This keyword allows to require the presence of properties that match some pattern(s).
@@ -379,6 +402,8 @@ var invalidDataList = [
 ];
 ```
 
+__Please note__: `{prohibited: ['foo', 'bar']}` is equivalent to `{not: {anyRequired: ['foo', 'bar']}}` (i.e. it has the same validation result for any data).
+
 
 #### `deepProperties`
 

keywords/anyRequired.js

@@ -0,0 +1,24 @@
+'use strict';
+
+module.exports = function defFunc(ajv) {
+  defFunc.definition = {
+    type: 'object',
+    macro: function (schema) {
+      if (schema.length == 0) return {};
+      if (schema.length == 1) return { required: schema };
+      var schemas = schema.map(function (prop) {
+        return { required: [prop] };
+      });
+      return { anyOf: schemas };
+    },
+    metaSchema: {
+      type: 'array',
+      items: {
+        type: 'string'
+      }
+    }
+  };
+
+  ajv.addKeyword('anyRequired', defFunc.definition);
+  return ajv;
+};

keywords/index.js

@@ -7,6 +7,7 @@ module.exports = {
   'typeof': require('./typeof'),
   dynamicDefaults: require('./dynamicDefaults'),
   allRequired: require('./allRequired'),
+  anyRequired: require('./anyRequired'),
   prohibited: require('./prohibited'),
   uniqueItemProperties: require('./uniqueItemProperties'),
   deepProperties: require('./deepProperties'),

spec/schema-tests.spec.js

@@ -7,6 +7,7 @@ var defineKeywords = require('..');
 var ajvs = [
   defineKeywords(getAjv(), [
     'allRequired',
+    'anyRequired',
     'deepProperties',
     'deepRequired',
     'formatMaximum',

spec/tests/anyRequired.json

@@ -0,0 +1,86 @@
+[
+  {
+    "description": "anyRequired requires that at least on property in the list is present",
+    "schema": {
+      "anyRequired": ["foo"]
+    },
+    "tests": [
+      {
+        "description": "property present is valid",
+        "data": {"foo": 1},
+        "valid": true
+      },
+      {
+        "description": "property present with an additional property is valid",
+        "data": {"foo": 1, "baz": 3},
+        "valid": true
+      },
+      {
+        "description": "no property present is invalid",
+        "data": { "baz": 1 },
+        "valid": false
+      },
+      {
+        "description": "empty object is invalid",
+        "data": {},
+        "valid": false
+      }
+    ]
+  },
+  {
+    "description": "multiple properties in prohibited",
+    "schema": {
+      "anyRequired": ["foo", "bar"]
+    },
+    "tests": [
+      {
+        "description": "property present is valid",
+        "data": {"foo": 1},
+        "valid": true
+      },
+      {
+        "description": "property present with an additional property is valid",
+        "data": {"foo": 1, "baz": 3},
+        "valid": true
+      },
+      {
+        "description": "all properties present is valid",
+        "data": {"foo": 1, "bar": 2},
+        "valid": true
+      },
+      {
+        "description": "all properties present with an additional property is valid",
+        "data": {"foo": 1, "bar": 2, "baz": 3},
+        "valid": true
+      },
+      {
+        "description": "no property present is invalid",
+        "data": {"baz": 3},
+        "valid": false
+      },
+      {
+        "description": "empty object is invalid",
+        "data": {},
+        "valid": false
+      }
+    ]
+  },
+  {
+    "description": "anyRequired: [] is always valid",
+    "schema": {
+      "anyRequired": []
+    },
+    "tests": [
+      {
+        "description": "any object is valid",
+        "data": {"foo": 1},
+        "valid": true
+      },
+      {
+        "description": "empty object is valid",
+        "data": {},
+        "valid": true
+      }
+    ]
+  }
+]