fix: remove conflicting child projections when parent path excluded

lib/helpers/projection/parseProjection.js

@@ -29,5 +29,20 @@ module.exports = function parseProjection(v, retainMinusPaths) {
     ret[field] = include;
   }
 
+  removeConflictingProjections(ret);
+
   return ret;
 };
+
+function removeConflictingProjections(projection) {
+  const keys = Object.keys(projection);
+  for (const key of keys) {
+    if (projection[key] === 0) {
+      for (const other of keys) {
+        if (other.startsWith(key + '.') && projection[other] === 0) {
+          delete projection[other];
+        }
+      }
+    }
+  }
+}

test/projection.pathCollision.test.js

@@ -0,0 +1,24 @@
+'use strict';
+
+const mongoose = require('../');
+const { Schema, model } = mongoose;
+const assert = require('assert');
+
+describe('Fix projection collision', function() {
+  it('removes children when parent is excluded', async function() {
+    const BarSchema = new Schema({
+      name: String,
+      subd: {
+        raw: { type: String, select: false },
+        clean: String
+      }
+    });
+
+    const Bar = model('Bar', BarSchema, 'bars');
+
+    const q = Bar.find({}).select('subd');
+    const proj = q._fields;
+
+    assert.deepStrictEqual(proj, { subd: 0 });
+  });
+});