fix: add default support

[dotkas]

No description provided.

[Copilot]

Pull request overview

Adds end-to-end support for OpenAPI default values during lowering and code emission, so missing optional fields/params can deserialize into concrete Rust values (and error out when a default cannot be represented).

Changes:

• Lower schema and query-parameter default into an IR DefaultValue, and adjust optionality so “optional + default” becomes non-Option<T> (except nullable).
• Emit #[serde(default = "...")] plus per-struct associated default fns, and introduce a dedicated UnsupportedDefault error for unrenderable defaults.
• Add fixtures + generated outputs + coverage table updates documenting and testing supported/unsupported defaults.

Reviewed changes

Copilot reviewed 17 out of 19 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
docs/design.md	Documents the new default/Option lowering rules and edge cases (nullable, required fields, unrepresentable defaults).
crates/oapi-codegen/tests/generated/server_query_params.rs	Updates generated query struct to use a serde default fn and non-optional limit.
crates/oapi-codegen/tests/generated/schema_defaults.rs	New generated output exercising defaults across scalar/enum/empty-collection/nullable cases.
crates/oapi-codegen/tests/generated.rs	Registers the new generated module.
crates/oapi-codegen/tests/fixtures/unsupported_default_value.yaml	New fixture covering an unrepresentable default (non-empty array).
crates/oapi-codegen/tests/fixtures/server_query_params.yaml	Adds a query-parameter default used to drive generation changes.
crates/oapi-codegen/tests/fixtures/schema_defaults.yaml	New fixture covering supported default shapes and semantics.
crates/oapi-codegen/tests/coverage.rs	Marks meta.default supported and adds an explicit unsupported sub-feature + fixtures; wires new generated test.
crates/oapi-codegen/src/lower/schema.rs	Computes declared defaults for object properties, adjusts optionality rules, and lowers defaults into IR fields.
crates/oapi-codegen/src/lower/recurse.rs	Updates test field construction for the new Field.default member.
crates/oapi-codegen/src/lower/paths.rs	Adds query-parameter default lowering and threads owner name for generated default fn paths.
crates/oapi-codegen/src/lower/mod.rs	Exposes new lower::default module.
crates/oapi-codegen/src/lower/default.rs	New lowering module that validates/normalizes JSON defaults against Rust types and enum wire values.
crates/oapi-codegen/src/ir.rs	Extends Field with default: Option<DefaultValue> and defines DefaultValue.
crates/oapi-codegen/src/error.rs	Adds Error::UnsupportedDefault with display + error trait integration.
crates/oapi-codegen/src/emit/usage.rs	Updates test helper Field construction for the new default member.
crates/oapi-codegen/src/emit/models.rs	Emits serde default attributes + associated default fns and renders DefaultValue into Rust expressions.
crates/oapi-codegen/src/console.rs	Routes UnsupportedDefault into hint printing.
crates/oapi-codegen/Cargo.toml	Adds serde_json dependency for default handling.

[Copilot]

Pull request overview

Copilot reviewed 17 out of 19 changed files in this pull request and generated no new comments.

Suppressed comments (2)

crates/oapi-codegen/src/lower/default.rs:64

• lower_default treats both i32 and i64 defaults via Value::as_i64() with no range check. For an int32 field, a schema default outside the i32 range will currently lower successfully and then fail later as a Rust compile error (literal/type mismatch). Prefer rejecting out-of-range values here so the generator reports a clear UnsupportedDefault error instead of producing uncompilable output.

        RustType::Bool => json.as_bool().map(DefaultValue::Bool),
        RustType::I32 | RustType::I64 => json.as_i64().map(DefaultValue::Int),

docs/design.md:310

• The example ?limit= is misleading: #[serde(default = ...)] only applies when the parameter is absent, not when it is present but empty. With axum_extra::extract::Query/serde_urlencoded, limit= will typically fail to deserialize into i32 rather than using the default. The text should describe omitting limit entirely.

A query parameter follows the same rule. `?limit=` with `default: 20` gives a
plain `i32` field.

[Copilot]

Pull request overview

Copilot reviewed 17 out of 19 changed files in this pull request and generated no new comments.

Suppressed comments (3)

docs/design.md:310

• The example ?limit= is a present-but-empty query parameter, not an absent parameter. A serde default only applies when the key is missing; with ?limit= deserialization of i32 will typically fail rather than falling back to the default. Reword this to describe an absent limit parameter (or use an example that omits limit entirely).

A query parameter follows the same rule. `?limit=` with `default: 20` gives a
plain `i32` field.

crates/oapi-codegen/Cargo.toml:27

• serde_json is now a normal dependency (needed by non-test code), but it is still listed in [dev-dependencies] as well. Keeping the same crate/version in both places is redundant and can drift over time; tests can use the normal dependency.

serde_json = "1.0.151"

crates/oapi-codegen/src/emit/models.rs:180

• Default functions are emitted whenever field.default is present, even when the struct does not derive any serde traits (has_serde == false). In that case emit_field suppresses the #[serde(default = "...")] attribute, so the generated default_* functions become unused and can trigger dead_code warnings in the generated crate. Gate emitting default functions (and the impl block) on has_serde.

    let mut defaults = Vec::new();
    for field in &strukt.fields {
        fields.push(emit_field(field, has_serde, &strukt.name)?);
        if let Some(value) = &field.default {
            defaults.push(emit_default_fn(field, value)?);

[Copilot]

Pull request overview

Copilot reviewed 17 out of 19 changed files in this pull request and generated no new comments.

Suppressed comments (2)

crates/oapi-codegen/src/emit/models.rs:246

• The generated doc string for default helper functions has a leading space (" The ..."), which will be rendered into rustdoc output and looks accidental. Removing it keeps documentation formatting clean.

    let doc = format!(" The `default` the document gives `{}`.", field.name.logical());

crates/oapi-codegen/src/lower/mod.rs:8

• lower is exported from the crate (pub mod lower in lib.rs), so making lower::default public also exposes this new internal module as part of the public API. If lower_default is only an implementation detail, keep the module private to avoid committing to it as a supported API surface.

pub mod default;

[Copilot]

Pull request overview

Copilot reviewed 17 out of 19 changed files in this pull request and generated no new comments.

Suppressed comments (3)

crates/oapi-codegen/src/lower/default.rs:47

• The hint string for UnsupportedDefault uses line-continuation (\) with indentation, which will embed large runs of whitespace in the emitted hint text. This makes the console hint harder to read/copy.

            hint: format!(
                "`{owner}.{property}` lowers to {}. Give it a `default` of that type, or remove the `default`. \
                 This generator renders a scalar, an enum value, an empty array, and an empty object. \
                 It cannot render a non-empty array or object.",
                describe(ty)

crates/oapi-codegen/src/lower/paths.rs:456

• query_field already resolves the parameter schema inside query_param_type, but query_param_default resolves/clones the schema again just to read schema_data.default. For inline (non-$ref) parameter schemas, this extra clone/work is avoidable.

    /// The `default` a query parameter's schema declares, if any.
    fn query_param_default(
        &self,
        path: &str,
        method: &str,
        origin: Option<&str>,
        data: &ParameterData,
    ) -> Result<Option<serde_json::Value>> {
        let ParameterSchemaOrContent::Schema(schema) = &data.format else {
            // `query_param_type` rejects a `content` parameter with a better
            // message than this could give.
            return Ok(None);
        };
        let schema = self.resolve_param_schema(path, method, origin, &data.name, schema)?;
        return Ok(schema.schema_data.default);
    }

docs/design.md:306

• The design doc implies that an “empty object” default works for any object-typed field, but the implementation only supports default: {} when the field lowers to a HashMap (RustType::Map). For struct-shaped objects (named types), {} has no literal form and will be rejected as an unsupported default. Clarifying this avoids misleading spec authors.

Only a value with a literal form works: a string, a number, a boolean, an enum
value, an empty array, and an empty object. A non-empty array, a non-empty
object, and a value of the wrong type are errors, not silent drops. A dropped

[Copilot]

Pull request overview

Copilot reviewed 17 out of 19 changed files in this pull request and generated no new comments.

[alchemax-housekeeper]

🎉 This PR is included in version 1.0.0-dev.27 🎉

The release is available on GitHub release

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[alchemax-housekeeper]

🎉 This PR is included in version 1.0.0 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀