Node.js Basics — MongoDB Complex Updates and Upserts
Tags: node, webdev, programming, javascript
Published: 2021-01-24 01:17:39

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Node.js is a popular runtime platform to create programs that run on it.

It lets us run JavaScript outside the browser.

In this article, we’ll look at how to start using Node.js to create programs.

### Filtered Positional Operator for Arrays in Documents

We can get the position and insert what we want into it.

For example, we can write:

```
const { MongoClient } = require('mongodb');
const connection = "mongodb://localhost:27017";
const client = new MongoClient(connection);

async function run() {
  try {
    await client.connect();
    const testCollection = await client.db("test").collection('test');
    const result = await testCollection.insertOne({
      name: "Popeye",
      address: "1 Sweethaven",
      items: [
        {
          type: "pizza",
          size: "large",
          toppings: ["garlic, spinach"],
        },
        {
          type: "calzone",
          toppings: ["ham"],
        },
      ],
    });
    console.log(result)
    const query = { name: "Popeye" };
    const options = {
      arrayFilters: [{
        "orderItem.type": "pizza",
        "orderItem.size": "large",
      }]
    };
    const updateDocument = {
      $push: { "items.$[orderItem].toppings": "veggie" }
    };
    const updateResult = await testCollection.updateOne(query, updateDocument, options);
    console.log(updateResult)
  } finally {
    await client.close();
  }
}
run().catch(console.dir);
```

We add the items into the `toppings` array of the object with the given `type` and `size` in the `items` array.

The `items.$[orderItem].toppings` gets the item with the given result from the `arrayFilters` search.

It’ll search the `items` array for the entry by replacing `orderItem` with the index of the search result in `arrayFilters` .

Now we should see `veggie` as the 2nd wntr of the `toppings` array property.

The document should now be:

```
{
   "_id":{
      "$oid":"5f68f03c9b873d2818970b52"
   },
   "name":"Popeye",
   "address":"1 Sweethaven",
   "items":[
      {
         "type":"pizza",
         "size":"large",
         "toppings":[
            "garlic, spinach",
            "veggie"
         ]
      },
      {
         "type":"calzone",
         "toppings":[
            "ham"
         ]
      }
   ]
}
```

### Upsert

We can upsert one or more documents with the `updateOne` , `replaceOne` or `updateMany` methods.

To update a single entry, we can use the `updateOne` method:

```
const { MongoClient } = require('mongodb');
const connection = "mongodb://localhost:27017";
const client = new MongoClient(connection);

async function run() {
  try {
    await client.connect();
    const testCollection = await client.db("test").collection('test');
    const result = await testCollection.insertOne({
      name: "Popeye",
    });
    console.log(result)
    const query = { name: "Popeye" };
    const update = { $set: { name: "Popeye", address: "3 Nassau St" } };
    const options = {};
    const updateResult = await testCollection.updateOne(query, update, options);
    console.log(updateResult)
  } finally {
    await client.close();
  }
}
run().catch(console.dir);
```

We insert an item with a `name` key.

Then we call the `updateOne` with the `query` object to find the item with the given `name` value.

Then we create the `update` object with the `$set` property to update the properties with the items.

The `replaceOne` method lets us replace an item with another one.

For example, we can write:

```
const { MongoClient } = require('mongodb');
const connection = "mongodb://localhost:27017";
const client = new MongoClient(connection);

async function run() {
  try {
    await client.connect();
    const testCollection = await client.db("test").collection('test');
    const result = await testCollection.insertOne({
      name: "Popeye",
    });
    console.log(result)
    const query = { name: "Popeye" };
    const update = { name: "Popeye", address: "3 Nassau St" };
    const options = {};
    const updateResult = await testCollection.replaceOne(query, update, options);
    console.log(updateResult)
  } finally {
    await client.close();
  }
}
run().catch(console.dir);
```

We call `replaceOne` to replace the item with `name` set to `'Popeye'` to an object with both the `name` and `address` properties.

### Conclusion

We can call various methods to update our MongoDB documents.