CODEWITHSUNDEEP
crystal-lang
vtambourine
vtambourine

Reputation: 2149

What is the difference between JSON::Any and JSON::Type in Crystal?

In Crystal language, what is the difference between JSON::Any and JSON::Type? What are the use cases of this types?

Upvotes: 3

Views: 426

Answers (2)

peak
peak

Reputation: 116720

JSON::Type is a recursively-defined "alias":

alias Type = Nil | Bool | Int64 | Float64 | String | Array(Type) | Hash(String, Type)

Aliases are part of Crystal's type grammar. For details, see https://crystal-lang.org/docs/syntax_and_semantics/alias.html

JSON::Any is a Struct (Struct < Value < Object); an instance of JSON::Any holds the "raw" value of any JSON type:

cr(0.24.1) > x=JSON::Any.new("hi")
 => "hi"
icr(0.24.1) > x
 => "hi"
icr(0.24.1) > x.raw
 => "hi"

Upvotes: 2

Vitalii Elenhaupt
Vitalii Elenhaupt

Reputation: 7326

JSON::Any is a struct, which is returned as a result of parsing. It has convenient methods to access underlying data as_s, as_bool, as_f etc. :

obj = JSON.parse %({"access": true})
p obj.class           # => JSON::Any
p obj["access"]       # => true
p obj["access"].class # => JSON::Any

JSON::Type is an union type of all possible json types. It is used internally by JSON::Any struct to represent the data:

p obj.raw             # => {"access" => true}
p obj.raw.class       # => Hash(String, JSON::Type)

Upvotes: 5

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