Let's Go Further › Parsing JSON requests

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Chapter 4.

Parsing JSON requests

So far we’ve been looking at how to create and send JSON responses from our API, but in this next section of the book we’re going to explore things from the other side and discuss how to read and parse JSON requests from clients.

To help demonstrate this, we’re going to start working on the POST /v1/movies endpoint and createMovieHandler that we set up earlier.

Method	URL Pattern	Handler	Action
GET	/v1/healthcheck	healthcheckHandler	Show application information
POST	/v1/movies	createMovieHandler	Create a new movie
GET	/v1/movies/:id	showMovieHandler	Show the details of a specific movie

When a client calls this endpoint, we expect them to provide a JSON request body containing data for the movie they want to create in our system. So, for example, if a client wants to add a record for the movie Moana to our API, they would send a request body similar to this:

{
    "title": "Moana",
    "year": 2016,
    "runtime": 107,
    "genres": ["animation", "adventure"]
}

For now, we’ll just focus on the reading, parsing and validation aspects of dealing with this JSON request body. Specifically, you’ll learn:

How to read a request body and decode it to a native Go value using the encoding/json package.
How to deal with bad requests from clients and invalid JSON, and return clear, actionable, error messages.
How to create a reusable helper package for validating data to ensure it meets your business rules.
Different techniques for controlling and customizing how JSON is decoded.