feat(model): add Model.applyVirtuals() to apply virtuals to a POJO

Fix #14818

lib/helpers/document/applyVirtuals.js

@@ -0,0 +1,141 @@
+'use strict';
+
+const mpath = require('mpath');
+
+module.exports = applyVirtuals;
+
+function applyVirtuals(schema, doc, virtuals, parent) {
+  if (doc == null) {
+    return doc;
+  }
+
+  let virtualsForChildren = virtuals;
+  let toApply = null;
+
+  if (Array.isArray(virtuals)) {
+    virtualsForChildren = [];
+    toApply = [];
+    const len = virtuals.length;
+    for (let i = 0; i < len; ++i) {
+      const virtual = virtuals[i];
+      if (virtual.length === 1) {
+        toApply.push(virtual[0]);
+      } else {
+        virtualsForChildren.push(virtual);
+      }
+    }
+  }
+
+  applyVirtualsToChildren(this, schema, doc, virtualsForChildren, parent);
+  return applyVirtualsToDocs(schema, doc, toApply);
+}
+
+function applyVirtualsToDocs(schema, res, toApply) {
+  if (Array.isArray(res)) {
+    const len = res.length;
+    for (let i = 0; i < len; ++i) {
+      applyVirtualsToDoc(schema, res[i], toApply);
+    }
+    return res;
+  } else {
+    return applyVirtualsToDoc(schema, res, toApply);
+  }
+}
+
+function applyVirtualsToChildren(doc, schema, res, virtuals, parent) {
+  const len = schema.childSchemas.length;
+  let attachedVirtuals = false;
+  for (let i = 0; i < len; ++i) {
+    const _path = schema.childSchemas[i].model.path;
+    const _schema = schema.childSchemas[i].schema;
+    if (!_path) {
+      continue;
+    }
+    const _doc = mpath.get(_path, res);
+    if (_doc == null || (Array.isArray(_doc) && _doc.flat(Infinity).length === 0)) {
+      continue;
+    }
+
+    let virtualsForChild = null;
+    if (Array.isArray(virtuals)) {
+      virtualsForChild = [];
+      const len = virtuals.length;
+      for (let i = 0; i < len; ++i) {
+        const virtual = virtuals[i];
+        if (virtual[0] == _path) {
+          virtualsForChild.push(virtual.slice(1));
+        }
+      }
+
+      if (virtualsForChild.length === 0) {
+        continue;
+      }
+    }
+
+    applyVirtuals.call(doc, _schema, _doc, virtualsForChild, res);
+    attachedVirtuals = true;
+  }
+
+  if (virtuals && virtuals.length && !attachedVirtuals) {
+    applyVirtualsToDoc(schema, res, virtuals, parent);
+  }
+}
+
+function applyVirtualsToDoc(schema, doc, virtuals) {
+  if (doc == null || typeof doc !== 'object') {
+    return;
+  }
+  if (Array.isArray(doc)) {
+    for (let i = 0; i < doc.length; ++i) {
+      applyVirtualsToDoc(schema, doc[i], virtuals);
+    }
+    return;
+  }
+
+  if (schema.discriminators && Object.keys(schema.discriminators).length > 0) {
+    for (const discriminatorKey of Object.keys(schema.discriminators)) {
+      const discriminator = schema.discriminators[discriminatorKey];
+      const key = discriminator.discriminatorMapping.key;
+      const value = discriminator.discriminatorMapping.value;
+      if (doc[key] == value) {
+        schema = discriminator;
+        break;
+      }
+    }
+  }
+
+  if (virtuals == null) {
+    virtuals = Object.keys(schema.virtuals);
+  }
+  const numVirtuals = virtuals.length;
+  for (let i = 0; i < numVirtuals; ++i) {
+    const virtual = virtuals[i];
+    if (schema.virtuals[virtual] == null) {
+      continue;
+    }
+    const virtualType = schema.virtuals[virtual];
+    const sp = Array.isArray(virtual)
+      ? virtual :
+      virtual.indexOf('.') === -1
+        ? [virtual]
+        : virtual.split('.');
+    let cur = doc;
+    for (let j = 0; j < sp.length - 1; ++j) {
+      cur[sp[j]] = sp[j] in cur ? cur[sp[j]] : {};
+      cur = cur[sp[j]];
+    }
+    let val = virtualType.applyGetters(cur[sp[sp.length - 1]], doc);
+    if (isPopulateVirtual(virtualType) && val === undefined) {
+      if (virtualType.options.justOne) {
+        val = null;
+      } else {
+        val = [];
+      }
+    }
+    cur[sp[sp.length - 1]] = val;
+  }
+}
+
+function isPopulateVirtual(virtualType) {
+  return virtualType.options && (virtualType.options.ref || virtualType.options.refPath);
+}

lib/model.js

@@ -31,6 +31,7 @@ const applySchemaCollation = require('./helpers/indexes/applySchemaCollation');
 const applyStaticHooks = require('./helpers/model/applyStaticHooks');
 const applyStatics = require('./helpers/model/applyStatics');
 const applyWriteConcern = require('./helpers/schema/applyWriteConcern');
+const applyVirtualsHelper = require('./helpers/document/applyVirtuals');
 const assignVals = require('./helpers/populate/assignVals');
 const castBulkWrite = require('./helpers/model/castBulkWrite');
 const clone = require('./helpers/clone');
@@ -3488,6 +3489,9 @@ function handleSuccessfulWrite(document) {
  */
 
 Model.applyDefaults = function applyDefaults(doc) {
+  if (doc == null) {
+    return doc;
+  }
   if (doc.$__ != null) {
     applyDefaultsHelper(doc, doc.$__.fields, doc.$__.exclude);
 
@@ -3503,6 +3507,40 @@ Model.applyDefaults = function applyDefaults(doc) {
   return doc;
 };
 
+/**
+ * Apply this model's virtuals to a given POJO. Virtuals execute with the POJO as the context `this`.
+ *
+ * #### Example:
+ *
+ *     const userSchema = new Schema({ name: String });
+ *     userSchema.virtual('upper').get(function() { return this.name.toUpperCase(); });
+ *     const User = mongoose.model('User', userSchema);
+ *
+ *     const obj = { name: 'John' };
+ *     User.applyVirtuals(obj);
+ *     obj.name; // 'John'
+ *     obj.upper; // 'JOHN', Mongoose applied the return value of the virtual to the given object
+ *
+ * @param {Object} obj object or document to apply virtuals on
+ * @param {Array<string>} [virtualsToApply] optional whitelist of virtuals to apply
+ * @returns {Object} obj
+ * @api public
+ */
+
+Model.applyVirtuals = function applyVirtuals(doc, virtualsToApply) {
+  if (doc == null) {
+    return doc;
+  }
+  // Nothing to do if this is already a hydrated document - it should already have virtuals
+  if (doc.$__ != null) {
+    return doc;
+  }
+
+  applyVirtualsHelper(this.schema, doc, virtualsToApply, null);
+
+  return doc;
+};
+
 /**
  * Cast the given POJO to the model's schema
  *