Prisma.js: Code-first ORM in JavaScript

Listing 9. Finding tags by idea and ideas by tags

// Display ideas with a given tag
app.get('/ideas/tag/:tagId', async (req, res) => {
  const { tagId } = req.params;

  try {
    const tag = await prisma.tag.findUnique({
      where: {
        id: parseInt(tagId)
      }
    });

    const ideas = await prisma.idea.findMany({
      where: {
        tags: {
          some: {
            id: tag.id
          }
        }
      }
    });

    res.json(ideas);
  } catch (error) {
    console.error('Error retrieving ideas with tag:', error);
    res.status(500).json({
      error: 'An error occurred while retrieving the ideas with the tag'
    });
  }
});

// tags on an idea:
app.get('/ideatags/:ideaId', async (req, res) => {
  const { ideaId } = req.params;
  try {
    const idea = await prisma.idea.findUnique({
      where: {
        id: parseInt(ideaId)
      }
    });

    const tags = await prisma.tag.findMany({
      where: {
        ideas: {
          some: {
            id: idea.id
          }
        }
      }
    });

    res.json(tags);
  } catch (error) {
    console.error('Error retrieving tags for idea:', error);
    res.status(500).json({
      error: 'An error occurred while retrieving the tags for the idea'
    });
  }
});

Here, we have two endpoints: /ideas/tag/:tagId and /ideatags/:ideaId. They work very similarly to find ideas for a given tag ID and tags on a given idea ID. Essentially, the querying works just like it would in a one-to-many relationship, and Prisma deals with walking the lookup table. For example, for finding tags on an idea, we use the tag.findMany method with a where clause looking for ideas with the relevant ID, as shown in Listing 10.

Listing 10. Testing the tag-idea many-to-many relationship

$ curl -X POST -H "Content-Type: application/json" -d '{"name":"Funny Stuff"}' http://localhost:3000/tags

$ curl -X POST http://localhost:3000/ideas/1/tags/2
{"idea":{"id":1,"name":"New Idea","description":"Idea description","ownerId":3},"tag":{"id":2,"name":"Funny Stuff"}}

$ curl localhost:3000/ideas/tag/2
[{"id":1,"name":"New Idea","description":"Idea description","ownerId":3}]

$ curl localhost:3000/ideatags/1
[{"id":1,"name":"New Tag"},{"id":2,"name":"Funny Stuff"}]

Conclusion

Although we have hit on some CRUD and relationship basics here, Prisma is capable of much more. It gives you cascading operations like cascading delete, fetching strategies that allow you to fine-tune how objects are returned from the database, transactions, a query and filter API, and more. Prisma also allows you to migrate your database schema in accord with the model. Moreover, it keeps your application database-agnostic by abstracting all database client work in the framework. 

Prisma puts a lot of convenience and power at your fingertips for the cost of defining and maintaining the model definition. It’s easy to see why this ORM tool for JavaScript is a popular choice for developers.