[Fix] parse: allow parsing of empty keys in objects

ljharb · Mar 5, 2022 · 1d5ccca · 1d5ccca
1 parent 066fae6
commit 1d5ccca
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Showing 3 changed files with 58 additions and 3 deletions.
diff --git a/README.md b/README.md
@@ -299,6 +299,23 @@ assert.deepEqual(primitiveValues, { a: '15', b: 'true', c: 'null' });
 
 If you wish to auto-convert values which look like numbers, booleans, and other values into their primitive counterparts, you can use the [query-types Express JS middleware](https://github.com/xpepermint/query-types) which will auto-convert all request query parameters.
 
+
+### Parsing empty keys
+
+By default, empty keys are omitted after parsing:
+
+```javascript
+var obj = qs.parse("=1&=2");
+assert.deepEqual(withNull, {});
+```
+
+It is possible to include empty keys by using `allowEmptyKeys` flag:
+
+```javascript
+var obj = qs.parse("=1&=2", { allowEmptyKeys: true });
+assert.deepEqual(withNull, { "": ["1","2"] });
+```
+
 ### Stringifying
 
 [](#preventEval)

diff --git a/lib/parse.js b/lib/parse.js
@@ -7,6 +7,7 @@ var isArray = Array.isArray;
 
 var defaults = {
     allowDots: false,
+    allowEmptyKeys: false,
     allowPrototypes: false,
     allowSparse: false,
     arrayLimit: 20,
@@ -83,6 +84,9 @@ var parseValues = function parseQueryStringValues(str, options) {
         var key, val;
         if (pos === -1) {
             key = options.decoder(part, defaults.decoder, charset, 'key');
+            if (key === '') {
+                continue;
+            }
             val = options.strictNullHandling ? null : '';
         } else {
             key = options.decoder(part.slice(0, pos), defaults.decoder, charset, 'key');
@@ -148,7 +152,7 @@ var parseObject = function (chain, val, options, valuesParsed) {
 };
 
 var parseKeys = function parseQueryStringKeys(givenKey, val, options, valuesParsed) {
-    if (!givenKey) {
+    if (!givenKey && (!options.allowEmptyKeys || givenKey !== '')) {
         return;
     }
 
@@ -168,7 +172,7 @@ var parseKeys = function parseQueryStringKeys(givenKey, val, options, valuesPars
     // Stash the parent if it exists
 
     var keys = [];
-    if (parent) {
+    if (parent || (options.allowEmptyKeys && parent === '')) {
         // If we aren't using plain objects, optionally prefix keys that would overwrite object prototype properties
         if (!options.plainObjects && has.call(Object.prototype, parent)) {
             if (!options.allowPrototypes) {
@@ -217,6 +221,7 @@ var normalizeParseOptions = function normalizeParseOptions(opts) {
 
     return {
         allowDots: typeof opts.allowDots === 'undefined' ? defaults.allowDots : !!opts.allowDots,
+        allowEmptyKeys: typeof opts.allowEmptyKeys === 'undefined' ? defaults.allowEmptyKeys : !!opts.allowEmptyKeys,
         allowPrototypes: typeof opts.allowPrototypes === 'boolean' ? opts.allowPrototypes : defaults.allowPrototypes,
         allowSparse: typeof opts.allowSparse === 'boolean' ? opts.allowSparse : defaults.allowSparse,
         arrayLimit: typeof opts.arrayLimit === 'number' ? opts.arrayLimit : defaults.arrayLimit,

diff --git a/test/parse.js b/test/parse.js
@@ -847,10 +847,43 @@ test('parse()', function (t) {
 
 test('parses empty keys', function (t) {
     emptyTestCases.forEach(function (testCase) {
+        t.test('parses an object with empty string key with ' + testCase.input, function (st) {
+            st.deepEqual(qs.parse(testCase.input, { allowEmptyKeys: true }), testCase.withEmptyKeys);
+            st.deepEqual(qs.parse(testCase.stringifyOutput, { allowEmptyKeys: true }), testCase.withEmptyKeys);
+
+            st.end();
+        });
+
         t.test('skips empty string key with ' + testCase.input, function (st) {
-            st.deepEqual(qs.parse(testCase.input), testCase.noEmptyKeys);
+            st.deepEqual(
+                qs.parse(testCase.input),
+                testCase.noEmptyKeys
+            );
+
+            st.deepEqual(
+                qs.parse(testCase.input, { allowEmptyKeys: false }),
+                testCase.noEmptyKeys
+            );
 
             st.end();
         });
     });
+
+    t.test('edge case with object/arrays', function (st) {
+        st.deepEqual(
+            qs.parse('[][0]=2&[][1]=3', { allowEmptyKeys: true }),
+            { '': { '': ['2', '3'] } },
+            'array/object conversion',
+            { skip: 'TODO: figure out what this should do' }
+        );
+
+        st.deepEqual(
+            qs.parse('[][0]=2&[][1]=3&[a]=2', { allowEmptyKeys: true }),
+            { '': { '': ['2', '3'], a: '2' } },
+            'array/object conversion',
+            { skip: 'TODO: figure out what this should do' }
+        );
+
+        st.end();
+    });
 });