document selectn dot-property accessors

Author: Cache Hamm

docs/rules.md

@@ -188,7 +188,6 @@ let rule = new Rule({
         fact: 'product-price',
         params: {
           productId: 'widget',
-          // Complex accessor are supported, e.g. '.profile.addresses[0].city'
           path: '.price'
         },
         operator: 'greaterThan',
@@ -198,7 +197,34 @@ let rule = new Rule({
   }
 })
 ```
-See the [fact-dependency](../examples/04-fact-dependency.js) example
+
+To access nested properties, use dot/bracket-notation:
+```js
+  /*
+  {
+    profile: {
+      addresses: [{ city: 'Denver' }]
+    }
+  }
+  */
+
+  path: '.profile.addresses[0].city'  // "Denver"
+```
+
+To access properties with a '.', pass an array of properties
+```js
+ /*
+  {
+    property: {
+      'dot.property': 'hello-world'
+    }
+  }
+  */
+  path: ['property', 'dot.property']  // "hello-world"
+```
+Full documentation for `path` can be found in the [selectn](https://github.com/wilmoore/selectn.js) library
+
+For an example, see [fact-dependency](../examples/04-fact-dependency.js)
 
 ### Comparing facts
 

test/engine-fact.test.js

@@ -23,6 +23,7 @@ async function eligibilityData (params, engine) {
       name: 'Colorado'
     },
     zip: '80403',
+    'dot.property': 'dot-property-value',
     occupantHistory: [
       { name: 'Joe', year: 2011 },
       { name: 'Jane', year: 2013 }
@@ -171,6 +172,16 @@ describe('Engine: fact evaluation', () => {
         expect(successSpy).to.have.been.calledWith(event)
       })
 
+      it('correctly interprets "path" when target object properties have dots', async () => {
+        let complexCondition = conditions()
+        complexCondition.any[0].path = ['address', 'dot.property']
+        complexCondition.any[0].value = 'dot-property-value'
+        complexCondition.any[0].operator = 'equal'
+        setup(complexCondition)
+        await engine.run()
+        expect(successSpy).to.have.been.calledWith(event)
+      })
+
       it('correctly interprets "path" with runtime fact objects', async () => {
         let fact = { x: { y: 1 }, a: 2 }
         let conditions = {