Replace stub for mongDB lesson (use model.findOne) (#36493)

* Replace stub for mongDB lesson (use model.findOne)

Add solution

* Use callback in `createAndSavePerson()`

guide/english/certifications/apis-and-microservices/mongodb-and-mongoose/use-model.findone-to-return-a-single-matching-document-from-your-database/index.md

@@ -1,10 +1,65 @@
 ---
 title: Use model.findOne() to Return a Single Matching Document from Your Database
 ---
-## Use model.findOne() to Return a Single Matching Document from Your Database
+# Use model.findOne() to Return a Single Matching Document from Your Database
 
-This is a stub. <a href='https://github.com/freecodecamp/guides/tree/master/src/pages/certifications/apis-and-microservices/mongodb-and-mongoose/use-model.findone-to-return-a-single-matching-document-from-your-database/index.md' target='_blank' rel='nofollow'>Help our community expand it</a>.
+## Solutions
 
-<a href='https://github.com/freecodecamp/guides/blob/master/README.md' target='_blank' rel='nofollow'>This quick style guide will help ensure your pull request gets accepted</a>.
+<details><summary>Solution #1 (Click to Show/Hide)</summary>
 
-<!-- The article goes here, in GitHub-flavored Markdown. Feel free to add YouTube videos, images, and CodePen/JSBin embeds  -->
+Code for `myApp.js`
+
+```javascript
+/** 1) Install & Set up mongoose */
+const mongoose = require('mongoose');
+mongoose.connect(process.env.MONGO_URI);
+
+/** 2) Create a 'Person' Model */
+var personSchema = new mongoose.Schema({
+  name: String,
+  age: Number,
+  favoriteFoods: [String]
+});
+
+/** 3) Create and Save a Person */
+var Person = mongoose.model('Person', personSchema);
+
+var createAndSavePerson = function(done) {
+  var janeFonda = new Person({name: "Jane Fonda", age: 84, favoriteFoods: ["vodka", "air"]});
+
+  janeFonda.save(function(err, data) {
+    if (err) return console.error(err);
+    done(null, data)
+  });
+};
+
+/** 4) Create many People with `Model.create()` */
+var arrayOfPeople = [
+  {name: "Frankie", age: 74, favoriteFoods: ["Del Taco"]},
+  {name: "Sol", age: 76, favoriteFoods: ["roast chicken"]},
+  {name: "Robert", age: 78, favoriteFoods: ["wine"]}
+];
+var createManyPeople = function(arrayOfPeople, done) {
+  Person.create(arrayOfPeople, function (err, people) {
+    if (err) return console.log(err);
+    done(null, people);
+  });
+};
+
+/** 5) Use `Model.find()` */
+var findPeopleByName = function(personName, done) {
+  Person.find({name: personName}, function (err, personFound) {
+    if (err) return console.log(err);
+    done(null, personFound);
+  });
+};
+
+/** 6) Use `Model.findOne()` */
+var findOneByFood = function(food, done) {
+  Person.findOne({favoriteFoods: food}, function (err, data) {
+    if (err) return console.log(err);
+    done(null, data);
+  });
+};
+```
+</details>