emuto

Tutorial

Setup

To follow this tutorial, you will need emuto and emuto-cli. Don't worry, you can install them really easily:

npm install -g emuto emuto-cli

Requesting data from an API

In this tutorial we'll play with this fun little Star Wars API:

curl "https://swapi.co/api/people/1/"

{"name":"Luke Skywalker","height":"172","mass":"77","hair_color":"blond","skin_color":"fair","eye_color":"blue","birth_year":"19BBY","gender":"male","homeworld":"https://swapi.co/api/planets/1/","films":["https://swapi.co/api/films/2/","https://swapi.co/api/films/6/","https://swapi.co/api/films/3/","https://swapi.co/api/films/1/","https://swapi.co/api/films/7/"],"species":["https://swapi.co/api/species/1/"],"vehicles":["https://swapi.co/api/vehicles/14/","https://swapi.co/api/vehicles/30/"],"starships":["https://swapi.co/api/starships/12/","https://swapi.co/api/starships/22/"],"created":"2014-12-09T13:50:51.644000Z","edited":"2014-12-20T21:17:56.891000Z","url":"https://swapi.co/api/people/1/"}

Pretty-printing the JSON with emuto

Just pipe the results to emuto. It will automatically convert it to a much more readable and pleasant format:

curl "https://swapi.co/api/people/1/" | emuto

{
  "name": "Luke Skywalker",
  "height": "172",
  "mass": "77",
  "hair_color": "blond",
  "skin_color": "fair",
  "eye_color": "blue",
  "birth_year": "19BBY",
  "gender": "male",
  "homeworld": "https://swapi.co/api/planets/1/",
  "films": [
    "https://swapi.co/api/films/2/",
    "https://swapi.co/api/films/6/",
    "https://swapi.co/api/films/3/",
    "https://swapi.co/api/films/1/",
    "https://swapi.co/api/films/7/"
  ],
  "species": [ "https://swapi.co/api/species/1/" ],
  "vehicles": [ "https://swapi.co/api/vehicles/14/", "https://swapi.co/api/vehicles/30/" ],
  "starships": [ "https://swapi.co/api/starships/12/", "https://swapi.co/api/starships/22/" ],
  "created": "2014-12-09T13:50:51.644000Z",
  "edited": "2014-12-20T21:17:56.891000Z",
  "url": "https://swapi.co/api/people/1/"
}

Let's start filtering data

That's way more data than we actually need. Let's just return the character's name:

curl "https://swapi.co/api/people/1/" | emuto '$.name'

"Luke Skywalker"

Creating new data structures

Let's create a new data structure by combining the filters $.name and $.gender:

curl "https://swapi.co/api/people/1/" | emuto '{"name": $.name, "gender": $.gender}'

{ "name": "Luke Skywalker", "gender": "male" }

Chaining filters

It's possible to chain two filters together using the pipe character |. Let's chain $.films and length together to find how many films our character appeared in.

curl "https://swapi.co/api/people/1/" | emuto '$.films | length'

5

Now there's nothing stopping us from putting that into our new data structure as well! (I omitted gender for simplicity's sake)

curl "https://swapi.co/api/people/1/" | emuto '{"name": $.name, "films": ($.films | length)}'

{ "name": "Luke Skywalker", "films": 5 }
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