some progress

node_modules/mongoose/lib/helpers/populate/getVirtual.js

@@ -0,0 +1,72 @@
+'use strict';
+
+module.exports = getVirtual;
+
+/*!
+ * ignore
+ */
+
+function getVirtual(schema, name) {
+  if (schema.virtuals[name]) {
+    return { virtual: schema.virtuals[name], path: void 0 };
+  }
+
+  const parts = name.split('.');
+  let cur = '';
+  let nestedSchemaPath = '';
+  for (let i = 0; i < parts.length; ++i) {
+    cur += (cur.length > 0 ? '.' : '') + parts[i];
+    if (schema.virtuals[cur]) {
+      if (i === parts.length - 1) {
+        return { virtual: schema.virtuals[cur], path: nestedSchemaPath };
+      }
+      continue;
+    }
+
+    if (schema.nested[cur]) {
+      continue;
+    }
+
+    if (schema.paths[cur] && schema.paths[cur].schema) {
+      schema = schema.paths[cur].schema;
+      const rest = parts.slice(i + 1).join('.');
+
+      if (schema.virtuals[rest]) {
+        if (i === parts.length - 2) {
+          return {
+            virtual: schema.virtuals[rest],
+            nestedSchemaPath: [nestedSchemaPath, cur].filter(v => !!v).join('.')
+          };
+        }
+        continue;
+      }
+
+      if (i + 1 < parts.length && schema.discriminators) {
+        for (const key of Object.keys(schema.discriminators)) {
+          const res = getVirtual(schema.discriminators[key], rest);
+          if (res != null) {
+            const _path = [nestedSchemaPath, cur, res.nestedSchemaPath].
+              filter(v => !!v).join('.');
+            return {
+              virtual: res.virtual,
+              nestedSchemaPath: _path
+            };
+          }
+        }
+      }
+
+      nestedSchemaPath += (nestedSchemaPath.length > 0 ? '.' : '') + cur;
+      cur = '';
+      continue;
+    }
+
+    if (schema.discriminators) {
+      for (const discriminatorKey of Object.keys(schema.discriminators)) {
+        const virtualFromDiscriminator = getVirtual(schema.discriminators[discriminatorKey], name);
+        if (virtualFromDiscriminator) return virtualFromDiscriminator;
+      }
+    }
+
+    return null;
+  }
+}