fix(populate+discriminator): handle populating document whose discriminator value is different from discriminator model name

Fix #8324

Author: vkarpov15

lib/helpers/discriminator/getConstructor.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const getDiscriminatorByValue = require('../../queryhelpers').getDiscriminatorByValue;
+const getDiscriminatorByValue = require('./getDiscriminatorByValue');
 
 /*!
  * Find the correct constructor, taking into account discriminators

lib/helpers/discriminator/getDiscriminatorByValue.js

@@ -0,0 +1,27 @@
+'use strict';
+
+/*!
+* returns discriminator by discriminatorMapping.value
+*
+* @param {Model} model
+* @param {string} value
+*/
+
+module.exports = function getDiscriminatorByValue(model, value) {
+ let discriminator = null;
+ if (!model.discriminators) {
+   return discriminator;
+ }
+ for (const name in model.discriminators) {
+   const it = model.discriminators[name];
+   if (
+     it.schema &&
+     it.schema.discriminatorMapping &&
+     it.schema.discriminatorMapping.value == value
+   ) {
+     discriminator = it;
+     break;
+   }
+ }
+ return discriminator;
+}

lib/helpers/populate/getModelsMapForPopulate.js

@@ -2,6 +2,7 @@
 
 const MongooseError = require('../../error/index');
 const get = require('../get');
+const getDiscriminatorByValue = require('../discriminator/getDiscriminatorByValue');
 const isPathExcluded = require('../projection/isPathExcluded');
 const getSchemaTypes = require('./getSchemaTypes');
 const getVirtual = require('./getVirtual');
@@ -297,12 +298,18 @@ module.exports = function getModelsMapForPopulate(model, docs, options) {
 
       if (!schema && discriminatorKey) {
         modelForFindSchema = utils.getValue(discriminatorKey, doc);
-
         if (modelForFindSchema) {
-          try {
-            modelForCurrentDoc = model.db.model(modelForFindSchema);
-          } catch (error) {
-            return error;
+          // `modelForFindSchema` is the discriminator value, so we might need
+          // find the discriminated model name
+          const discriminatorModel = getDiscriminatorByValue(model, modelForFindSchema);
+          if (discriminatorModel != null) {
+            modelForCurrentDoc = discriminatorModel;
+          } else {
+            try {
+              modelForCurrentDoc = model.db.model(modelForFindSchema);
+            } catch (error) {
+              return error;
+            }
           }
 
           schemaForCurrentDoc = modelForCurrentDoc.schema._getSchema(options.path);

lib/model.js

@@ -30,7 +30,7 @@ const assignVals = require('./helpers/populate/assignVals');
 const castBulkWrite = require('./helpers/model/castBulkWrite');
 const discriminator = require('./helpers/model/discriminator');
 const each = require('./helpers/each');
-const getDiscriminatorByValue = require('./queryhelpers').getDiscriminatorByValue;
+const getDiscriminatorByValue = require('./helpers/discriminator/getDiscriminatorByValue');
 const getModelsMapForPopulate = require('./helpers/populate/getModelsMapForPopulate');
 const immediate = require('./helpers/immediate');
 const internalToObjectOptions = require('./options').internalToObjectOptions;

lib/query.js

@@ -18,6 +18,7 @@ const castArrayFilters = require('./helpers/update/castArrayFilters');
 const castUpdate = require('./helpers/query/castUpdate');
 const completeMany = require('./helpers/query/completeMany');
 const get = require('./helpers/get');
+const getDiscriminatorByValue = require('./helpers/discriminator/getDiscriminatorByValue');
 const hasDollarKeys = require('./helpers/query/hasDollarKeys');
 const helpers = require('./queryhelpers');
 const isInclusive = require('./helpers/projection/isInclusive');
@@ -4429,7 +4430,7 @@ Query.prototype._castUpdate = function _castUpdate(obj, overwrite) {
       typeof filter[schema.options.discriminatorKey] !== 'object' &&
       schema.discriminators != null) {
     const discriminatorValue = filter[schema.options.discriminatorKey];
-    const byValue = helpers.getDiscriminatorByValue(this.model, discriminatorValue);
+    const byValue = getDiscriminatorByValue(this.model, discriminatorValue);
     schema = schema.discriminators[discriminatorValue] ||
       (byValue && byValue.schema) ||
       schema;

lib/queryhelpers.js

@@ -7,6 +7,8 @@
 const checkEmbeddedDiscriminatorKeyProjection =
   require('./helpers/discriminator/checkEmbeddedDiscriminatorKeyProjection');
 const get = require('./helpers/get');
+const getDiscriminatorByValue =
+  require('./helpers/discriminator/getDiscriminatorByValue');
 const isDefiningProjection = require('./helpers/projection/isDefiningProjection');
 const utils = require('./utils');
 
@@ -71,34 +73,6 @@ exports.preparePopulationOptionsMQ = function preparePopulationOptionsMQ(query,
   return pop;
 };
 
-
-/*!
- * returns discriminator by discriminatorMapping.value
- *
- * @param {Model} model
- * @param {string} value
- */
-function getDiscriminatorByValue(model, value) {
-  let discriminator = null;
-  if (!model.discriminators) {
-    return discriminator;
-  }
-  for (const name in model.discriminators) {
-    const it = model.discriminators[name];
-    if (
-      it.schema &&
-      it.schema.discriminatorMapping &&
-      it.schema.discriminatorMapping.value == value
-    ) {
-      discriminator = it;
-      break;
-    }
-  }
-  return discriminator;
-}
-
-exports.getDiscriminatorByValue = getDiscriminatorByValue;
-
 /*!
  * If the document is a mapped discriminator type, it returns a model instance for that type, otherwise,
  * it returns an instance of the given model.

lib/schema/array.js

@@ -17,7 +17,7 @@ const util = require('util');
 const utils = require('../utils');
 const castToNumber = require('./operators/helpers').castToNumber;
 const geospatial = require('./operators/geospatial');
-const getDiscriminatorByValue = require('../queryhelpers').getDiscriminatorByValue;
+const getDiscriminatorByValue = require('../helpers/discriminator/getDiscriminatorByValue');
 
 let MongooseArray;
 let EmbeddedDoc;

lib/types/documentarray.js

@@ -8,7 +8,7 @@ const CoreMongooseArray = require('./core_array');
 const Document = require('../document');
 const ObjectId = require('./objectid');
 const castObjectId = require('../cast/objectid');
-const getDiscriminatorByValue = require('../queryhelpers').getDiscriminatorByValue;
+const getDiscriminatorByValue = require('../helpers/discriminator/getDiscriminatorByValue');
 const internalToObjectOptions = require('../options').internalToObjectOptions;
 const util = require('util');
 const utils = require('../utils');

test/model.populate.test.js

@@ -8825,7 +8825,6 @@ describe('model: populate:', function() {
         yield Model.create({ main: d._id });
 
         const docs = yield Main.find().populate('virtualField').exec();
-        console.log(docs.map(d => d.virtualField))
         assert.ok(docs[0].virtualField[0].main);
       });
     });