Compile JSON Schema documents into Rust types. This can be used ...
-
via the macro
import_types!("types.json")to generate Rust types directly in your program -
via a builder interface to generate Rust types in
build.rs -
or via the builder functions to generate persistent files e.g. when building API bindings.
We can divide types in JSON Schema into a few classes:
Integers, floating-point numbers, strings, etc. Those all have straightforward translations. The only significant nuance is how to select the appropriate built-in type.
JSON Schema arrays can turn into three Rust types Vec<T>, HashSet<T>, and
tuples. Arrays may have a fixed length that matches a fixed list of item types;
this matches well with Rust tuples. The distintion between Vec<T> and HashSet<T> is only if the uniqueItems field is true.
In general Objects turn in to Rust structs, but if there are no properties
defined Typify models this as a HashMap<String, T> if the
additionalProperties schema specifies T or a HashMap<String, serde_json::Value> otherwise. Properties that are not in the required set and represented as an Option<T>.
The OneOf construct maps to a Rust enum. Typify maps this to the various serde enum types.
The anyOf and allOf constructs are a little trickier to handle, but (in
general) Typify models these as structs where each member is decorated with the
#[serde(flatten)] attribute.
Typify is a work in progress. Changes that affect output will likely be breaking changes. We will continue to update the crate version number with each change; be cognizant when updating to a new version.
Bounded numbers aren't very well handled. Consider, for example, the schema:
{
"type": "integer",
"minimum": 1,
"maximum": 6
}The resulting types won't enforce those value constraints.
Similarly, patterns and lengths for strings are not enforced.
In general, if you have a JSON Schema that causes Typify to fail or if the generated type isn't what you expect, please file an issue.