Comparison helpers should still execute when their key parameter is s…

…et but resolves to undefined.

Previously, if a helper's key parameter was set, but the Dust variable to which it pointed did not exist, the helper would immediately abort. However, this breaks cases especially for {@ne} in which it would be completely valid if the key did not exist.

The helper will still fail to execute if a key parameter is not passed. However, if the parameter resolves to an undefined variable, it will now execute.

This is a non-backwards-compatible change. Closes #59.

lib/dust-helpers.js

@@ -33,18 +33,17 @@ function filter(chunk, context, bodies, params, filterOp) {
  actualKey,
  expectedValue,
  filterOpType = params.filterOpType || '';
+
  // when @eq, @lt etc are used as standalone helpers, key is required and hence check for defined
- if ( typeof params.key !== "undefined") {
+ if (params.hasOwnProperty("key")) {
  actualKey = dust.helpers.tap(params.key, chunk, context);
- }
- else if (isSelect(context)) {
+ } else if (isSelect(context)) {
  actualKey = context.current().selectKey;
  // supports only one of the blocks in the select to be selected
  if (context.current().isResolved) {
  filterOp = function() { return false; };
  }
- }
- else {
+ } else {
  _log("No key specified for filter in:" + filterOpType + " helper ");
  return chunk;
  }
@@ -57,19 +56,17 @@ function filter(chunk, context, bodies, params, filterOp) {
  // we want helpers without bodies to fail gracefully so check it first
  if(body) {
  return chunk.render(body, context);
- }
- else {
- _log("No key specified for filter in:" + filterOpType + " helper ");
+ } else {
+ _log("No body specified for " + filterOpType + " helper ");
  return chunk;
  }
- }
- else if (bodies['else']) {
+ } else if (bodies['else']) {
  return chunk.render(bodies['else'], context);
  }
  return chunk;
 }
 
-function coerce (value, type, context) {
+function coerce(value, type, context) {
  if (value) {
  switch (type || typeof(value)) {
  case 'number': return +value;

test/jasmine-test/spec/helpersTests.js

@@ -497,11 +497,18 @@
  },
  {
  name: "eq helper with no params",
- source: "{@eq}Hello{/eq}",
+ source: "{@eq}Hello{:else}Goodbye{/eq}",
  context: {},
  expected: "",
  message: "eq helper with no params does not execute"
  },
+ {
+ name: "eq helper with key that resolves to undefined",
+ source: "{@eq key=foo value=\"0\"}Hello{:else}Goodbye{/eq}",
+ context: {},
+ expected: "Goodbye",
+ message: "eq helper with key that resolves to undefined executes {:else}"
+ },
  {
  name: "eq helper matching string case",
  source: "{@eq key=\"foo\" value=\"foo\"}equal{/eq}",