Understanding Responders

To understand the concepts behind responders, we must understand the three variables that affect how controllers respond: request type, HTTP verb, and resource status.

Navigational and API Requests

A controller the scaffold generator creates responds to two formats by default: HTML and JavaScript Object Notation (JSON). The scaffold generator uses these two formats because they represent two types of requests: navigational and API. The former is handled by a browser and holds formats like HTML and MOBILE, whereas the latter is used by machines and represents formats like XML and JSON.

​ 
​def​ index
​ 
@users = User.all
​ 
respond_to ​do​ |format|
​ 
format.html ​# index.html.erb​
​ 
format.json ...

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