fix(package): improve workaround for obj.toString

add workaround for keySet/entrySet/size
add helpers 'walk'
add tests

index.js

@@ -79,27 +79,50 @@ module.exports = function(template, payload, params, context) {
     }
   };
 
-  // API Gateway convert function to "{}" on toString.
+  // Workaround to followings
+  // When the tempalte is "$input.params" (= function)
+  //   - AWS API Gateway returns "{}".
+  //   - This is not org.apache.velocity's behaviour. It returns "$input.params".
+  // When the tempalte is "$input" or "$input"
+  //   - AWS API Gateway returns "{}"
+  //   - This is not org.apache.velocity's behaviour. It returns serialized hash.
   var returnEmptyObject = function() { return "{}"; };
-  [
-    data.input,
-    data.input.params,
-    data.input.path,
-    data.input.json,
-    data.util,
-    data.util.escapeJavaScript,
-    data.util.urlEncode,
-    data.util.urlDecode,
-    data.util.base64Encode,
-    data.util.base64Decode,
-  ].forEach(function(f) {
-    f.toString = returnEmptyObject;
+
+  // This never be called because velocity.js will process.
+  // But I want to handling only toString
+  var builtinMethod = function() { throw "unexpected error"; };
+  builtinMethod.toString = returnEmptyObject;
+
+  data.input.toString = returnEmptyObject;
+  data.util.toString = returnEmptyObject;
+  walk(data, function(obj) {
+    if (typeof(obj) == 'function') {
+      obj.toString = returnEmptyObject;
+    }
+
+    obj.keySet = builtinMethod;
+    obj.entrySet = builtinMethod;
+    obj.size = builtinMethod;
   });
 
   var ast = Velocity.parse(template.toString());
   return (new Velocity.Compile(ast)).render(data);
 };
 
+function walk(obj, cb) {
+  cb(obj);
+
+  if (Array.isArray(obj)) {
+    obj.forEach(function(c) {
+      walk(c, cb);
+    });
+  } else if ({}.toString.call(obj) === '[object Object]') {
+    Object.keys(obj).forEach(function(k) {
+      walk(obj[k], cb);
+    });
+  }
+}
+
 function base64Encode(x) {
   return (new Buffer(x)).toString('base64');
 }

misc/gen.js

@@ -195,6 +195,16 @@ var post = require('./post');
     payload: "",
     headers: {},
   },
+  {
+    template: '$input.keySet',
+    payload: "",
+    headers: {},
+  },
+  {
+    template: '$input.params.keySet',
+    payload: "",
+    headers: {},
+  },
   {
     template: '$util',
     payload: "",

test/_.js

@@ -132,6 +132,22 @@ describe('$input.path|$input.json', function() {
       assert.deepEqual(expected, actual);
     });
   });
+  // https://github.com/ToQoz/api-gateway-mapping-template/blob/master/test/_.md#example-ec2bf3b4
+  describe('H=`{}` P=`` ===> T=`$input.keySet`', function() {
+    it('return ', function() {
+      var expected = {};
+      var actual = JSON.parse(mappingTemplate("$input.keySet", "", {}));
+      assert.deepEqual(expected, actual);
+    });
+  });
+  // https://github.com/ToQoz/api-gateway-mapping-template/blob/master/test/_.md#example-3e03488f
+  describe('H=`{}` P=`` ===> T=`$input.params.keySet`', function() {
+    it('return ', function() {
+      var expected = {};
+      var actual = JSON.parse(mappingTemplate("$input.params.keySet", "", {}));
+      assert.deepEqual(expected, actual);
+    });
+  });
   // https://github.com/ToQoz/api-gateway-mapping-template/blob/master/test/_.md#example-a35f2355
   describe('H=`{}` P=`` ===> T=`$util`', function() {
     it('return ', function() {

test/_.md

@@ -83,6 +83,16 @@ Template|Header|Payload|Status code|Result
 --------|------|-------|-----------|------
 `$input`|`None`|``|`200`|`{}`
 
+## example-ec2bf3b4
+Template|Header|Payload|Status code|Result
+--------|------|-------|-----------|------
+`$input.keySet`|`None`|``|`200`|`{}`
+
+## example-3e03488f
+Template|Header|Payload|Status code|Result
+--------|------|-------|-----------|------
+`$input.params.keySet`|`None`|``|`200`|`{}`
+
 ## example-a35f2355
 Template|Header|Payload|Status code|Result
 --------|------|-------|-----------|------