索引到JSON

Question

This seems like it should be a very easy question but I'm having some trouble with it. I'm creating my own JSON and I need to index into it in order to seed by database. I've indexed into JSONs before with very little difficulty, but for some reason I can't index into my own. That makes me think that there might be an issue with my JSON itself, but I can't see anything that would cause an issue. I appreciate your assistance!

My JSON:

{
    "workouts": [
        {
            "level": "1",
            "exercises": [
                {
                    "name": "box jumps",
                    "difficulty": "3",
                    "reps": "10",
                    "sets": "3",
                    "requirements": [
                        "sturdy box at least two feet high"
                    ],
                    "body-part": "quadriceps",
                    "description": "Plant both feet should length apart and jump onto the box. Once on the box, stand fully upright.",
                    "pounds": "1"
                },
                {
                    "name": "v-press",
                    "difficulty": "4",
                    "reps": "12",
                    "sets": "3",
                    "requirements": [
                        "mat"
                    ],
                    "body-part": "abdominals",
                    "description": "Lie flat on the ground, then raise your legs and arms slightly off the matt.",
                    "pounds": "1"
                }
            ]
        },
        {
            "level": "2",
            "exercises": [
                {
                    "name": "assisted pullups",
                    "difficulty": "1",
                    "reps": "12",
                    "sets": "3",
                    "requirements": [
                        "Assisted Pullup Machine"
                    ],
                    "body-part": "biceps",
                    "description": "Kneel on the machine and adjust the weight to your needs",
                    "pounds": "50"
                },
                {
                    "name": "assisted dips",
                    "difficulty": "1",
                    "reps": "12",
                    "sets": "3",
                    "requirements": [
                        "Assisted Dips Machine"
                    ],
                    "body-part": "triceps",
                    "description": "Kneel on the machine and adjust the weight to your needs",
                    "pounds": "50"
                }
            ]
        }
    ]
}

In pry, I do the following:

require "json"
f= File.open("workout.json")
mylist = JSON.parse(f.read)

When I try to index in, I get various errors (syntax error, no method errors, nil). Below are some examples of indexing I have attempted.

mylist.workouts
mylist[:workouts]
mylist[0]
mylist[:workouts][0][:level]

Thanks in advance!

Answer 1

The keys in the Hash after parsing the JSON data are strings not symbols. Try this :

mylist['workouts']
mylist['workouts'][0]['level']

A couple of points to remember :

1. Strings and Symbols are not interchangeable as keys in a Hash . They both are different objects and hence different keys.
2. To get the behaviour of the params in Rails controller where strings and symbols are interchangeable you need to instantiate an instance of HashWithInDifferentAccess . It is a separate utility class provided by Rails and is not part of the Ruby stdlib
3. The gem jbuilder is not a JSON parser. It is a JSON creator. It is used to create JSON structures from Ruby objects, used mostly in writing views for JSON responses. It is analogous to how ERB is used for HTML responses.
4. JSON has been part of Ruby stdlib for some time now (ie JSON parsing and serialization does not require any additional gems).