Ruby On Rails | What is format.html/json for?

Question

So I have been going through Rails Zombies and have gotten to the part explaining format.html and .json My question is what do these lines of code do, and why do we have them? If I write these methods or actions without these format codes they work perfectly fine, as i'd assume they simply display in html format by default? If somebody could clear up exactly what this code does I'd be grateful, I also do not fully understand what JSON is.

def create
    @zombie = Zombie.new(zombie_params)

    respond_to do |format|
      if @zombie.save
        format.html { redirect_to @zombie, notice: 'Zombie was successfully created.' }
        format.json { render :show, status: :created, location: @zombie }
      else
        format.html { render :new }
        format.json { render json: @zombie.errors, status: :unprocessable_entity }
      end
    end

nbkhope · Accepted Answer · 2017-05-18 00:56:35Z

2

In simple terms:

If the request wants an HTML page, it will perform the instructions set by the block given to format.html.

If the request wants application/json (like when you make an Ajax request), the response will be given as instructed in the block given to format.json.

You should know what JSON means before delving into creating any web service. See http://www.json.org/

answered May 18, 2017 at 0:56

nbkhope

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5 Comments

Gerry Over a year ago

Actually you will use format.js for Ajax requests, format.json is more suitable for an API.

Colton Van Bastelaere Over a year ago

So when would I use JSON and why?

nbkhope Over a year ago

JSON is the preferred way nowadays to serve data from a web service. In the past people liked to use XML. But now JSON has taken over. You should really learn about it first before going full force into web development. Also, read about SOA, Service Oriented Architecture.

nbkhope Over a year ago

An example of a fake API that serves json: jsonplaceholder.typicode.com Try their endpoints, for instance jsonplaceholder.typicode.com/users

Colton Van Bastelaere Over a year ago

@nbkhope thank you very much this has cleared up lots for me!

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