memoizes the Populate function

src/fields/performFieldOperations.js

@@ -1,6 +1,8 @@
+const memoize = require('fast-memoize');
 const { ValidationError } = require('../errors');
 const sanitizeFallbackLocale = require('../localization/sanitizeFallbackLocale');
 const traverseFields = require('./traverseFields');
+const executeAccess = require('../auth/executeAccess');
 
 async function performFieldOperations(entityConfig, args) {
   const {
@@ -35,12 +37,72 @@ async function performFieldOperations(entityConfig, args) {
   // Maintain a top-level list of promises
   // so that all async field access / validations / hooks
   // can run in parallel
+
   const validationPromises = [];
   const accessPromises = [];
   const relationshipPopulations = [];
   const hookPromises = [];
   const errors = [];
 
+  // ////////////////////////////////////////////////////////////////
+  // Create memoized Populate function — with the same input (ID),
+  // it will return the same result without re-querying.
+  // Note - this function is recreated each time a request comes in
+  // ////////////////////////////////////////////////////////////////
+
+  const populate = memoize(async (
+    data,
+    dataReference,
+    field,
+    index,
+  ) => {
+    const dataToUpdate = dataReference;
+
+    const relation = Array.isArray(field.relationTo) ? data.relationTo : field.relationTo;
+    const relatedCollection = this.collections[relation];
+
+    if (relatedCollection) {
+      const accessResult = !overrideAccess ? await executeAccess({ req, disableErrors: true, id }, relatedCollection.config.access.read) : true;
+
+      let populatedRelationship = null;
+
+      if (accessResult && (depth && currentDepth <= depth)) {
+        let idString = Array.isArray(field.relationTo) ? data.value : data;
+
+        if (typeof idString !== 'string') {
+          idString = idString.toString();
+        }
+
+        populatedRelationship = await this.operations.collections.findByID({
+          req,
+          collection: relatedCollection,
+          id: idString,
+          currentDepth: currentDepth + 1,
+          disableErrors: true,
+          depth,
+        });
+      }
+
+      // If access control fails, update value to null
+      // If populatedRelationship comes back, update value
+      if (!accessResult || populatedRelationship) {
+        if (typeof index === 'number') {
+          if (Array.isArray(field.relationTo)) {
+            dataToUpdate[field.name][index].value = populatedRelationship;
+          } else {
+            dataToUpdate[field.name][index] = populatedRelationship;
+          }
+        } else if (Array.isArray(field.relationTo)) {
+          dataToUpdate[field.name].value = populatedRelationship;
+        } else {
+          dataToUpdate[field.name] = populatedRelationship;
+        }
+      }
+    }
+  }, {
+    serializer: (populateArgs) => JSON.stringify(populateArgs[0]),
+  });
+
   // //////////////////////////////////////////
   // Entry point for field validation
   // //////////////////////////////////////////
@@ -69,6 +131,7 @@ async function performFieldOperations(entityConfig, args) {
     validationPromises,
     errors,
     payload: this,
+    populate,
   });
 
   await Promise.all(hookPromises);