feat(pathError hook): add pathError hook for errors identified while

merging jsonGraphs

if a route returns a jsonGraph that has a node inside of it that is of
`$type: 'error'`, then during the merge process the `pathError` hook
will be called.

Just add a `hooks.pathError` function to the options argument to
`Router` ctor:

```js
var router = new Router(routes, {
  hooks: {
    pathError: function (pathValue) { }
  }
});
```

src/Router.js

@@ -14,6 +14,7 @@ var Router = function(routes, options) {
  this._rst = parseTree(routes);
  this._matcher = matcher(this._rst);
  this._debug = opts.debug;
+ this._pathErrorHook = (opts.hooks && opts.hooks.pathError) || noOp;
  this._errorHook = (opts.hooks && opts.hooks.error) || noOp;
  this.maxRefFollow = opts.maxRefFollow || MAX_REF_FOLLOW;
  this.maxPaths = opts.maxPaths || MAX_PATHS;

src/cache/jsongMerge.js

@@ -1,21 +1,23 @@
 var iterateKeySet = require('falcor-path-utils').iterateKeySet;
 var types = require('./../support/types');
 var $ref = types.$ref;
+var $error = types.$error;
 var clone = require('./../support/clone');
 var cloneArray = require('./../support/cloneArray');
 var catAndSlice = require('./../support/catAndSlice');
 
 /**
  * merges jsong into a seed
  */
-module.exports = function jsongMerge(cache, jsongEnv) {
+module.exports = function jsongMerge(cache, jsongEnv, routerInstance) {
  var paths = jsongEnv.paths;
  var j = jsongEnv.jsonGraph;
  var references = [];
  var values = [];
 
  paths.forEach(function(p) {
  merge({
+ router: routerInstance,
  cacheRoot: cache,
  messageRoot: j,
  references: references,
@@ -49,6 +51,12 @@ function merge(config, cache, message, depth, path, fromParent, fromKey) {
  if (message === null || typeOfMessage !== 'object' || message.$type) {
  fromParent[fromKey] = clone(message);
 
+ // If we notice an error while merging, we'll fire the error hook
+ // for logging purposes.
+ if (message && message.$type === $error) {
+ config.router._pathErrorHook({ path: path, value: message });
+ }
+
  // NOTE: If we have found a reference at our cloning position
  // and we have resolved our path then add the reference to
  // the unfulfilledRefernces.

src/router/get.js

@@ -53,7 +53,7 @@ module.exports = function routerGet(paths) {
  mCGRI(out.jsonGraph, [{
  jsonGraph: jsonGraphFragment.jsonGraph,
  paths: unhandledPaths
- }]);
+ }], router);
  return out;
  }).
  defaultIfEmpty(out);

src/router/set.js

@@ -137,7 +137,7 @@ module.exports = function routerSet(jsonGraph) {
  mCGRI(out.jsonGraph, [{
  jsonGraph: unhandledJsonGraphEnv.jsonGraph,
  paths: unhandledPaths
- }]);
+ }], router);
  return out;
  }).
  defaultIfEmpty(out);

src/run/call/runCallAction.js

@@ -84,7 +84,8 @@ function runCallAction(matchAndPath, routerInstance, callPath, args,
 
  });
 
- var invsRefsAndValues = mCGRI(jsongCache, callOutput);
+ var invsRefsAndValues =
+ mCGRI(jsongCache, callOutput, routerInstance);
  invsRefsAndValues.references.forEach(function(ref) {
  refs[++refLen] = ref;
  });

src/run/mergeCacheAndGatherRefsAndInvalidations.js

@@ -14,7 +14,9 @@ module.exports = mergeCacheAndGatherRefsAndInvalidations;
  * @param {Object} cache
  * @param {Array} jsongOrPVs
  */
-function mergeCacheAndGatherRefsAndInvalidations(cache, jsongOrPVs) {
+function mergeCacheAndGatherRefsAndInvalidations(
+ cache, jsongOrPVs, routerInstance
+) {
  var references = [];
  var len = -1;
  var invalidations = [];
@@ -39,7 +41,7 @@ function mergeCacheAndGatherRefsAndInvalidations(cache, jsongOrPVs) {
  }
 
  else if (isJSONG(jsongOrPV)) {
- refsAndValues = jsongMerge(cache, jsongOrPV);
+ refsAndValues = jsongMerge(cache, jsongOrPV, routerInstance);
  }
 
  // Last option are path values.

src/run/recurseMatchAndExecute.js

@@ -77,7 +77,8 @@ function _recurseMatchAndExecute(
  value = [value];
  }
 
- var invsRefsAndValues = mCGRI(jsongCache, value);
+ var invsRefsAndValues =
+ mCGRI(jsongCache, value, routerInstance);
  var invalidations = invsRefsAndValues.invalidations;
  var unhandled = invsRefsAndValues.unhandledPaths;
  var messages = invsRefsAndValues.messages;

src/run/set/runSetAction.js

@@ -67,7 +67,7 @@ function runSetAction(routerInstance, jsongMessage, matchAndPath, jsongCache) {
  paths: [match.requested]
  };
  arg = {};
- jsongMerge(arg, subJsonGraphEnv);
+ jsongMerge(arg, subJsonGraphEnv, routerInstance);
  }
  try {
  out = match.action.call(routerInstance, arg);

test/unit/core/get.spec.js

@@ -619,6 +619,68 @@ describe('Get', function() {
  subscribe(noOp, done, done);
  });
 
+ it('should fire the error hook if the graph node in it', function (done) {
+ var callCount = 0;
+ var callContext = null;
+ var callArgs = null;
+ var router = new R([{
+ route: 'videos[{integers:ids}].title',
+ get: function (alias) {
+ return Observable.of({
+ jsonGraph: {
+ videos: {
+ 1: {
+ title: { $type: 'error', value: { message: 'bad luck for you' } }
+ }
+ }
+ }
+ });
+ }
+ }],
+ {
+ hooks: {
+ pathError: function () {
+ callCount++;
+ callArgs = Array.prototype.slice.call(arguments, 0);
+ callContext = this;
+ }
+ }
+ });
+
+ router.get([['videos',1,'title']])
+ .do(
+ function (jsonGraph) {
+ expect(jsonGraph).to.deep.equal({
+ jsonGraph: {
+ 'videos': {
+ 1: {
+ 'title': {
+ $type: 'error', value: {
+ message: 'bad luck for you'
+ }
+ }
+ }
+ }
+ }
+ })
+ },
+ noOp,
+ function () {
+ expect(callCount).to.equal(1);
+ expect(callArgs).to.deep.equal([{
+ path: ['videos', 1, 'title'],
+ value: { $type: 'error', value: { message: 'bad luck for you' } }
+ }]);
+ expect(callContext).to.equal(router);
+ }
+ )
+ .subscribe(
+ noOp,
+ done,
+ done
+ )
+ });
+
  it('should fire the error hook passed in via options.hooks', function (done) {
  var callCount = 0;
  var callContext = null;

test/unit/internal/jsongMerge.spec.js

@@ -215,6 +215,47 @@ describe('JSONG - Merge', function() {
  }]
  });
  });
+
+ it('should fire the router error hook if $type:"error" is found while walking', function () {
+ var jsong = {
+ jsonGraph: {
+ this: {
+ is: {
+ deep: {
+ yo: { $type: 'error', value: { message: 'lol error' } }
+ }
+ }
+ }
+ },
+ paths: [['this', 'is', 'deep', 'yo']]
+ };
+ var callArgs = null;
+ var callCount = 0;
+ var mockRouter = {
+ _pathErrorHook: function () {
+ callCount++;
+ callArgs = Array.prototype.slice.call(arguments);
+ }
+ }
+ var cache = {};
+ var out = jsongMerge(cache, jsong, mockRouter);
+ expect(out).to.deep.equal({
+ values: [{
+ path: ['this', 'is', 'deep', 'yo'],
+ value: { $type: 'error', value: { message: 'lol error' } }
+ }],
+ references: []
+ });
+ expect(callArgs).to.deep.equals([
+ {
+ path: ['this', 'is', 'deep', 'yo'],
+ value : {
+ $type: 'error', value: { message: 'lol error'}
+ }
+ }
+ ]);
+ expect(callCount).to.equals(1);
+ });
 });
 
 function mergeTest(jsong) {