Chapter 5, “Fluent and Persisting Models”, explained the concept of models and how to store them in a database using Fluent. This chapter concentrates on how to interact with models in the database. You’ll learn about CRUD operations and how they relate to REST APIs. You’ll also see how to leverage Fluent to perform complex queries on your models.
Note: This chapter requires you to use PostgreSQL. Follow the steps in Chapter 5, “Fluent and Persisting Models”, to set up PostgreSQL in Docker and configure your Vapor application.
CRUD and REST
CRUD operations — Create, Retrieve, Update, Delete — form the four basic functions of persistent storage. With these, you can perform most actions required for your application. You actually implemented the first function, create, in Chapter 5.
RESTful APIs provide a way for clients to call the CRUD functions in your application. Typically you have a resource URL for your models. For the TIL application, this is the acronym resource: http://localhost:8080/api/acronyms. You then define routes on this resource, paired with appropriate HTTP request methods, to perform the CRUD operations. For example:
In Chapter 5, “Fluent and Persisting Models”, you implemented the create route for an Acronym. You can either continue with your project or open the TILApp in the starter folder for this chapter. To recap, you created a new route handler in routes.swift:
For TILApp, retrieve consists of two separate operations: retrieve all the acronyms and retrieve a single, specific acronym. Fluent makes both of these tasks easy.
Retrieve all acronyms
To retrieve all acronyms, create a route handler for GET requests to /api/acronyms/. Open routes.swift and add the following at the end of routes(_:):
Mevp rju batiotj xo nia mgi untejxhz ucsuexn ew pdi mumakezi:
Retrieve a single acronym
Vapor’s parameters integrate with Fluent’s querying functions to make it easy to get acronyms by IDs. To get a single acronym, you need a new route handler. Open routes.swift and add the following at the end of routes(_:):
// 1
app.get("api", "acronyms", ":acronymID") {
req -> EventLoopFuture<Acronym> in
// 2
Acronym.find(req.parameters.get("acronymID"), on: req.db)
// 3
.unwrap(or: Abort(.notFound))
}
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Delete
To delete a model in a RESTful API, you send a DELETE request to the resource. Add the following to the end of routes(_:) to create a new route handler:
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Hitt i nujeafn nu cey ihv lha anrekhtd ilz hee’ks kau qxu JDY ownazpm or qi daflud af mju huqazegi.
Fluent queries
You’ve seen how easy Fluent makes basic CRUD operations. It can perform more powerful queries just as easily.
Filter
Search functionality is a common feature in applications. If you want to search all the acronyms in the database, Fluent makes this easy. Ensure the following line of code is at the top of routes.swift:
import Fluent
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Diofv itj hid naam anpgitoveah, bjal ypeapa u say qolierp iz KALWud. Bavzuqeku gde suzuink em zicqopq:
Ruri: Qxoxic ux ANPh mojv mu EZF-elkecox ic oiwxor %74 eb + li ra pesoz.
First result
Sometimes an application needs only the first result of a query. Creating a specific handler for this ensures the database only returns one result rather than loading all results into memory. Create a new route handler to return the first acronym at the end of routes(_:):
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You now know how to use Fluent to perform the different CRUD operations and advanced queries. At this stage, routes.swift is getting cluttered with all the code from this chapter. The next chapter looks at how to better organize your code using controllers.
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