Generate Rust models and reqwest API clients

.github/workflows/ci.yaml

@@ -37,6 +37,8 @@ jobs:
       - uses: moonrepo/setup-toolchain@v0
         with:
           moon-version: "2.5.5"
+      - run: rustup toolchain install 1.98.1 --profile minimal
+      - run: rustup default 1.98.1
       - run: mkdir -p "$HOME/.cache/go-build"
       - name: Check affected tasks
         id: ci

.gitignore

@@ -12,3 +12,7 @@ test-results/
 *.pprof
 dump-*.json
 **/.moon/cache/
+
+/testdata/rust-client/target/
+/testdata/rust-client/src/public/
+/testdata/rust-client/src/models/

.golangci.yaml

@@ -68,6 +68,9 @@ linters:
       - path: ^internal/tsemit/tsemit\.go$
         linters: [gosec]
         text: G301|G306
+      - path: ^internal/rustemit/rustemit\.go$
+        linters: [gosec]
+        text: G301|G306
       # CLI input paths are intentionally supplied by the caller.
       - path: ^internal/openapi/openapi\.go$
         linters: [gosec]

README.md

@@ -1,6 +1,6 @@
 # OASmith
 
-OASmith generates focused Go and TypeScript code from OpenAPI YAML or JSON
+OASmith generates focused Go, TypeScript, and Rust code from OpenAPI YAML or JSON
 documents.
 It supports focused generation modes without the runtime and configuration
 surface of a general-purpose OpenAPI generator.
@@ -12,6 +12,8 @@ surface of a general-purpose OpenAPI generator.
 | `types` | `go` | Go models |
 | `client` | `go` | Go models and HTTP client |
 | `client` | `typescript` | TypeScript types and HTTP client |
+| `types` | `rust` | Serde models in `mod.rs` |
+| `client` | `rust` | Serde models and a Reqwest client in `mod.rs` |
 
 OASmith handles the OpenAPI schema and operation subset covered by its fixture
 suite, including objects, arrays, enums, `oneOf` discriminators, parameters,
@@ -39,7 +41,7 @@ Every invocation requires:
 
 - `--openapi`: input OpenAPI YAML or JSON document;
 - `--mode`: `types` or `client`;
-- `--lang`: `go` or `typescript`, subject to the supported pairs above;
+- `--lang`: `go`, `typescript`, or `rust`, subject to the supported pairs above;
 - `--out`: generated output directory.
 
 JSON input is supported alongside YAML. The document syntax is accepted
@@ -162,3 +164,22 @@ reports are attached to the workflow, including on failure.
 ## License
 
 [MIT](LICENSE)
+
+## Rust clients
+
+Use `--mode client --lang rust --out src/api`, then `mod api;`. Add `serde` 1
+(with `derive`), `serde_json` 1, and `reqwest` 0.12 (with `json`) to Cargo dependencies.
+Choose the Reqwest TLS features appropriate to your application.
+
+Construct `api::Client::new(http, base_url, bearer_token)` with your configured
+Reqwest client. Operation methods return request builders, so callers own timeouts,
+cancellation, tracing, and bounded body reads. Models and operation-specific
+`Response::decode` enums preserve declared HTTP statuses; undeclared statuses
+retain their original response. SSE responses remain streaming Reqwest responses,
+leaving event framing and cancellation to the caller.
+
+Rust supports JSON and raw request bodies, optional bodies, scalar and repeated
+query parameters, headers, escaped path parameters, enums, nullable values and
+untagged `oneOf` models. Sequential multipart requests currently fail generation
+with an explicit unsupported-body error. Run `moon run oasmith:test-rust` to generate,
+compile, and execute the Rust contract fixtures.

internal/cli/cli.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/responsibleapi/oasmith/internal/goemit"
 	"github.com/responsibleapi/oasmith/internal/openapi"
+	"github.com/responsibleapi/oasmith/internal/rustemit"
 	"github.com/responsibleapi/oasmith/internal/tsemit"
 )
 
@@ -29,14 +30,16 @@ func Run(args []string) error {
 		return err
 	}
 	switch {
+	case opts.Lang == "rust":
+		return rustemit.Emit(doc, rustemit.Options{OutDir: opts.Out}, opts.Mode == "client")
 	case opts.Mode == "types" && opts.Lang == "go":
 		return goemit.Emit(doc, goemit.Options{OutDir: opts.Out, SourcePath: opts.OpenAPI})
 	case opts.Mode == "client" && opts.Lang == "go":
 		return goemit.EmitClient(doc, goemit.Options{OutDir: opts.Out, SourcePath: opts.OpenAPI})
 	case opts.Mode == "client" && opts.Lang == "typescript":
 		return tsemit.Emit(doc, tsemit.Options{OutDir: opts.Out})
 	default:
-		return fmt.Errorf("unsupported --mode/--lang pair %q/%q; valid pairs are types/go, client/go, and client/typescript", opts.Mode, opts.Lang)
+		return fmt.Errorf("unsupported --mode/--lang pair %q/%q; valid pairs are types/go, client/go, client/typescript, types/rust, and client/rust", opts.Mode, opts.Lang)
 	}
 }
 
@@ -49,14 +52,15 @@ func Parse(args []string) (Options, error) {
 	fs.StringVar(&opts.Lang, "lang", "", "output language")
 	fs.StringVar(&opts.Out, "out", "", "output directory")
 	if err := fs.Parse(args); err != nil {
-		return Options{}, fmt.Errorf("usage: oasmith --openapi <openapidoc> --mode <types|client> --lang <go|typescript> --out <dir>")
+		return Options{}, fmt.Errorf("usage: oasmith --openapi <openapidoc> --mode <types|client> --lang <go|typescript|rust> --out <dir>")
 	}
 	if opts.OpenAPI == "" || opts.Mode == "" || opts.Lang == "" || opts.Out == "" {
-		return Options{}, fmt.Errorf("usage: oasmith --openapi <openapidoc> --mode <types|client> --lang <go|typescript> --out <dir>")
+		return Options{}, fmt.Errorf("usage: oasmith --openapi <openapidoc> --mode <types|client> --lang <go|typescript|rust> --out <dir>")
 	}
-	if (opts.Mode == "types" && opts.Lang == "go") ||
+	if ((opts.Mode == "types" || opts.Mode == "client") && opts.Lang == "rust") ||
+		(opts.Mode == "types" && opts.Lang == "go") ||
 		(opts.Mode == "client" && (opts.Lang == "go" || opts.Lang == "typescript")) {
 		return opts, nil
 	}
-	return Options{}, fmt.Errorf("unsupported --mode/--lang pair %q/%q; valid pairs are types/go, client/go, and client/typescript", opts.Mode, opts.Lang)
+	return Options{}, fmt.Errorf("unsupported --mode/--lang pair %q/%q; valid pairs are types/go, client/go, client/typescript, types/rust, and client/rust", opts.Mode, opts.Lang)
 }

internal/cli/cli_test.go

@@ -31,7 +31,7 @@ func TestParseRejectsInvalidModeLangPair(t *testing.T) {
 	if err == nil {
 		t.Fatal("Parse invalid mode/lang succeeded")
 	}
-	if !strings.Contains(err.Error(), "valid pairs are types/go, client/go, and client/typescript") {
+	if !strings.Contains(err.Error(), "valid pairs are types/go, client/go, client/typescript, types/rust, and client/rust") {
 		t.Fatalf("Parse error = %q, want valid pair message", err.Error())
 	}
 }

internal/openapi/openapi.go

@@ -102,23 +102,24 @@ type Encoding struct {
 
 // Schema describes the OpenAPI schema subset supported by the generator.
 type Schema struct {
-	Ref              string             `yaml:"$ref"`
-	Title            string             `yaml:"title"`
-	Type             Type               `yaml:"type"`
-	Format           string             `yaml:"format"`
-	Description      string             `yaml:"description"`
-	Enum             []string           `yaml:"enum"`
-	Const            any                `yaml:"const"`
-	Properties       map[string]*Schema `yaml:"properties"`
-	Required         []string           `yaml:"required"`
-	Items            *Schema            `yaml:"items"`
-	PrefixItems      []*Schema          `yaml:"prefixItems"`
-	MinItems         *int               `yaml:"minItems"`
-	MaxItems         *int               `yaml:"maxItems"`
-	OneOf            []*Schema          `yaml:"oneOf"`
-	Discriminator    *Discriminator     `yaml:"discriminator"`
-	ContentMediaType string             `yaml:"contentMediaType"`
-	ContentSchema    *Schema            `yaml:"contentSchema"`
+	AdditionalProperties any                `yaml:"additionalProperties"`
+	Ref                  string             `yaml:"$ref"`
+	Title                string             `yaml:"title"`
+	Type                 Type               `yaml:"type"`
+	Format               string             `yaml:"format"`
+	Description          string             `yaml:"description"`
+	Enum                 []string           `yaml:"enum"`
+	Const                any                `yaml:"const"`
+	Properties           map[string]*Schema `yaml:"properties"`
+	Required             []string           `yaml:"required"`
+	Items                *Schema            `yaml:"items"`
+	PrefixItems          []*Schema          `yaml:"prefixItems"`
+	MinItems             *int               `yaml:"minItems"`
+	MaxItems             *int               `yaml:"maxItems"`
+	OneOf                []*Schema          `yaml:"oneOf"`
+	Discriminator        *Discriminator     `yaml:"discriminator"`
+	ContentMediaType     string             `yaml:"contentMediaType"`
+	ContentSchema        *Schema            `yaml:"contentSchema"`
 }
 
 // Type holds one or more OpenAPI schema type names.