llmrb-json_schema is a small, dependency-free library that can produce a JSON Schema through the composition of simple Ruby objects. It is an optional dependency of llmrb/llm where it is used to describe the response a Large Language Model (LLM) is expected to produce.
The following example demonstrates how to produce a schema that
describes a theoretical object with three properties: name, age,
and salary. Some properties are required, others have a default, and
some have a range of values:
#!/usr/bin/env ruby
require "json"
require "json/schema"
schema = JSON::Schema.new
schema.object({
name: schema.string.required,
age: schema.number.default(18),
salary: schema.number.min(65_000).max(120_000)
})
print JSON.pretty_generate(schema.to_h), "\n"The following example demonstrates how to produce a schema that describes an array of objects. It builds on the previous example by allowing an array of objects with the same properties, and it also allows the array to include "null" values:
#!/usr/bin/env ruby
require "json"
require "json/schema"
schema = JSON::Schema.new
schema.array(
schema.object({
name: schema.string.required,
age: schema.number.default(18),
salary: schema.number.min(65_000).max(120_000)
}),
schema.null
)
print JSON.pretty_generate(schema.to_h), "\n"Generally each JSON value can have certain constraints, such as a minimum or maximum value, whether or not it is a required item in an object, or has a default value. We have seen some of these in the previous examples. The following example demonstrates a few more. See the API reference for a complete list of constraints on a per-value basis:
#!/usr/bin/env ruby
require "json"
require "json/schema"
schema = JSON::Schema.new
schema.object({
name: schema.string.required,
age: schema.number.default(18),
salary: schema.number.min(65_000).max(120_000).multiple_of(5_000),
is_employee: schema.boolean.default(true)
})The README tries to provide a high-level overview of the library. For everything else there's the API reference. It covers classes and methods that the README glances over or doesn't cover at all. The API reference is available at 0x1eef.github.io/x/llmrb-json_schema.
llmrb-json_schema is available via RubyGems
gem install llmrb-json_schema