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crystal-lang

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?

Solution

  • 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)