fix string type checking and circular reference, working on #81

src/render.js

@@ -1,6 +1,7 @@
 const Syntax = require('./syntax.js')
 const mapSeries = require('./util/promise.js').mapSeries
 const RenderBreakError = require('./util/error.js').RenderBreakError
+const _ = require('./util/underscore.js')
 const RenderError = require('./util/error.js').RenderError
 const assert = require('./util/assert.js')
 
@@ -27,9 +28,7 @@ var render = {
         return this.renderTag(template, scope)
           .then(partial => partial === undefined ? '' : partial)
       } else if (template.type === 'value') {
-        return Promise.resolve()
-          .then(() => this.evalValue(template, scope))
-          .then(partial => partial === undefined ? '' : stringify(partial))
+        return this.renderValue(template, scope)
       } else { // template.type === 'html'
         return Promise.resolve(template.value)
       }
@@ -46,6 +45,12 @@ var render = {
     return template.render(scope)
   },
 
+  renderValue: function (template, scope) {
+    return Promise.resolve()
+      .then(() => this.evalValue(template, scope))
+      .then(partial => partial === undefined ? '' : _.stringify(partial))
+  },
+
   evalValue: function (template, scope) {
     assert(scope, 'unable to evalValue: scope undefined')
     return template.filters.reduce(
@@ -59,9 +64,4 @@ function factory () {
   return instance
 }
 
-function stringify (val) {
-  if (typeof val === 'string') return val
-  return JSON.stringify(val)
-}
-
 module.exports = factory

src/util/underscore.js

@@ -6,7 +6,27 @@ const toStr = Object.prototype.toString
  * @return {Boolean} Returns true if value is a string, else false.
  */
 function isString (value) {
-  return value instanceof String || typeof value === 'string'
+  return toStr.call(value) === '[object String]'
+}
+
+function stringify (value) {
+  if (isString(value)) {
+    return value
+  }
+  if (value && typeof value.to_liquid === 'function') {
+    return value.to_liquid()
+  }
+
+  let cache = []
+  return JSON.stringify(value, (key, value) => {
+    if (isObject(value)) {
+      if (cache.indexOf(value) !== -1) {
+        return
+      }
+      cache.push(value)
+    }
+    return value
+  })
 }
 
 function isNil (value) {
@@ -126,3 +146,4 @@ exports.last = last
 exports.forOwn = forOwn
 exports.assign = assign
 exports.uniq = uniq
+exports.stringify = stringify

test/render.js

@@ -17,11 +17,17 @@ describe('render', function () {
   var scope, render
 
   beforeEach(function () {
-    scope = Scope.factory({
+    var ctx = {
       foo: {
         bar: ['a', 2]
+      },
+      bar: {
+        to_liquid: x => 'custom'
       }
-    })
+    }
+    ctx.self = ctx
+
+    scope = Scope.factory(ctx)
     filter.clear()
     tag.clear()
     render = Render()
@@ -39,6 +45,34 @@ describe('render', function () {
     })
   })
 
+  describe('.renderValue()', function () {
+    it('should respect to .to_liquid() method', function () {
+      var tpl = Template.parseValue('bar')
+      return expect(render.renderValue(tpl, scope)).to.eventually.equal('custom')
+    })
+
+    it('should stringify objects', function () {
+      let scope = Scope.factory({
+        foo: { obj: { arr: ['a', 2] } }
+      })
+      let tpl = Template.parseValue('foo')
+      return expect(render.renderValue(tpl, scope)).to.eventually.equal('{"obj":{"arr":["a",2]}}')
+    })
+    it('should skip circular property', function () {
+      let ctx = { foo: { num: 2 }, bar: 'bar' }
+      ctx.foo.circular = ctx
+
+      let scope = Scope.factory(ctx)
+      let tpl = Template.parseValue('foo')
+      return expect(render.renderValue(tpl, scope)).to.eventually.equal('{"num":2,"circular":{"bar":"bar"}}')
+    })
+    it('should skip function property', function () {
+      let scope = Scope.factory({obj: {foo: 'foo', bar: x => x}})
+      let tpl = Template.parseValue('obj')
+      return expect(render.renderValue(tpl, scope)).to.eventually.equal('{"foo":"foo"}')
+    })
+  })
+
   it('should eval filter with correct arguments', function () {
     var date = sinon.stub().returns('y')
     var time = sinon.spy()
@@ -62,5 +96,10 @@ describe('render', function () {
       var tpl = Template.parseValue('foo.bar[0] | date: "b" | time:2')
       expect(render.evalValue(tpl, scope)).to.equal('ab6')
     })
+    it('should reserve type', function () {
+      filter.register('arr', () => [1])
+      var tpl = Template.parseValue('"x" | arr')
+      expect(render.evalValue(tpl, scope)).to.deep.equal([1])
+    })
   })
 })