CODEWITHSUNDEEP
rubyjson
linkyndy
linkyndy

Reputation: 17928

What's the preferred way to dump a JSON object? to_json, JSON.generate or JSON.dump?

I need to dump a hash object to JSON and I was wondering which of these three, to_json, JSON.generate or JSON.dump, is the preferred way to do it.

I've tested the results of these methods and they are the same:

> {a: 1, b: 2}.to_json
=> "{\"a\":1,\"b\":2}" 
> JSON.generate({a: 1, b: 2})
=> "{\"a\":1,\"b\":2}" 
> JSON.dump({a: 1, b: 2})
=> "{\"a\":1,\"b\":2}"

Upvotes: 11

Views: 15532

Answers (4)

EliadL
EliadL

Reputation: 7098

Working with a huge hash (300MB), to_json was unable to generate the json string, it crashed.
However JSON.generate did work, and so did JSON.dump.

Upvotes: 2

aligo
aligo

Reputation: 61

For dumping arrays, hashs and objects (converted by to_hash), these 3 ways are equivalent.

But JSON.generate or JSON.dump only allowed arrays, hashs and objects.

to_json accepts many Ruby classes even though it acts only as a method for serialization, like a integer:

JSON.generate 1 # would be allowed
1.to_json # => "1"

JSON.generate took more options for output style (like space, indent)

And JSON.dump, output default style, but took a IO-like object as second argument to write, third argument as limit number of nested arrays or objects.

Upvotes: 3

Amadan
Amadan

Reputation: 198566

From docs:

JSON.generate only allows objects or arrays to be converted to JSON syntax. to_json, however, accepts many Ruby classes even though it acts only as a method for serialization

and

[JSON.dumps] is part of the implementation of the load/dump interface of Marshal and YAML.

If anIO (an IO-like object or an object that responds to the write method) was given, the resulting JSON is written to it.

Upvotes: 9

pangpang
pangpang

Reputation: 8831

JSON.generate only allows objects or arrays to be converted to JSON syntax.

to_json accepts many Ruby classes even though it acts only as a method for serialization

JSON.generate(1)
JSON::GeneratorError: only generation of JSON objects or arrays allowed

1.to_json
=> "1"

JSON.dump: Dumps obj as a JSON string, calls generate on the object and returns the result.

You can get more info from here

Upvotes: 4

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