lesson_3.md

Lesson 3 - Update and import new data that links to old data

Remember the company phonebook stored in TerminusDB? It has been a few months and there is a new recruit:

Employee id	Name	Title	Team	Manager
005	Ethan Abbott	Backend Developer	IT	004

Employee id	Contact number	Home address	Postcode
005	070 7796 8035	84 Shore Street, Stoer	IV27 2TG

Also, the Marketing Manager Destiny has moved to a new address:

Employee id	Contact number	Home address	Postcode
001	(01986) 113367	73 Lairg Road, Newbigging	PH12 3RP

How are we going to update the records?

Getting data objects back from TerminusDB/ TerminusCMS

Let us first look at how to update Destiny's Address. We will use a script called update_data.js.

Let's examine the parts of the script. We import the Employee document that represents Destiny. Since we know the id, we will use getDocument:

const destiny = await client.getDocument({"id":"Employee/001"});

Update a document

We know destiny is an Employee object so we can go ahead and update the details:

  // will have to delete "@id" because the database will create a new one
  delete destiny.address['@id'];

  destiny.address.postcode = "PH12 3RP";
  destiny.address.street = "Lairg Road";
  destiny.address.street_num = 73;
  destiny.address.town = "Newbigging";
  

The script then sends destiny back to the database with updateDocument. The difference between addDocument and updateDocument is that if an object already exists updateDocument will replace the old with the new.

await client.updateDocument(destiny);

Linking a new document to an old document

Now let's work on our new recruit. We now create ethan and link Ethan's manager as Employee/004:

const ethan = {
    "@type": "Employee",
    "employee_id": "005",
    name: "Ethan Abbott",
    title: "Backend Developer",
    team: "IT",
    contact_number: "070 7796 8035",
    address: {
        "@type": "Address",
        postcode: "IV27 2TG",
        street: "Shore Street",
        street_num: 84,
        town: "Stoer"
    },
    manager: "Employee/004",
}

All is ready so we'll put ethan into the database. Use addDocument to insert ethan:

await client.addDocument(ethan);

Before running the script ensure to set the end point, team and user credentials.

Run the scripts:

$ node update_data.js

Use the terminal to check if the database is up-to-date:

const result = await client.getDocument({"as_list":true});
console.log(result);

If you are using TerminusCMS, you can also check it in the dashboard.

---

Lesson 4 - Query the database and get result back as JSON