## OpenAPI Client and Server Code Generator ⚠️ This README may be for the latest development version, which may contain unreleased changes. Please ensure you're looking at the README for the latest release version. This package contains a set of utilities for generating Go boilerplate code for services based on [OpenAPI 3.0](https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.0.md) API definitions. When working with services, it's important to have an API contract which servers and clients both implement to minimize the chances of incompatibilities. It's tedious to generate Go models which precisely correspond to OpenAPI specifications, so let our code generator do that work for you, so that you can focus on implementing the business logic for your service. We have chosen to focus on [Echo](https://github.com/labstack/echo) as our default HTTP routing engine, due to its speed and simplicity for the generated stubs. [Chi](https://github.com/go-chi/chi), [Gin](https://github.com/gin-gonic/gin), [gorilla/mux](https://github.com/gorilla/mux), and [Fiber](https://github.com/gofiber/fiber) have also been added by contributors as additional routers. We chose Echo because the `Context` object is a mockable interface, and it allows for some advanced testing. This package tries to be too simple rather than too generic, so we've made some design decisions in favor of simplicity, knowing that we can't generate strongly typed Go code for all possible OpenAPI Schemas. If there is a way to accomplish something via utility code or reflection, it's probably a better approach than code generation, which is fragile due to the very dynamic nature of OpenAPI and the very static nature of Go. ## Overview We're going to use the OpenAPI example of the [Expanded Petstore](https://github.com/OAI/OpenAPI-Specification/blob/master/examples/v3.0/petstore-expanded.yaml) in the descriptions below, please have a look at it. In order to create a Go server to serve this exact schema, you would have to write a lot of boilerplate code to perform all the marshalling and unmarshalling into objects which match the OpenAPI 3.0 definition. The code generator in this directory does a lot of that for you. You would run it like so: go install github.com/deepmap/oapi-codegen/cmd/oapi-codegen@latest oapi-codegen -package petstore petstore-expanded.yaml > petstore.gen.go Let's go through that `petstore.gen.go` file to show you everything which was generated. ## Generated Server Boilerplate The `/components/schemas` section in OpenAPI defines reusable objects, so Go types are generated for these. The Pet Store example defines `Error`, `Pet`, `Pets` and `NewPet`, so we do the same in Go: ```go // Error defines model for Error. type Error struct { // Error code Code int32 `json:"code"` // Error message Message string `json:"message"` } // NewPet defines model for NewPet. type NewPet struct { // Name of the pet Name string `json:"name"` // Type of the pet Tag *string `json:"tag,omitempty"` } // Pet defines model for Pet. type Pet struct { // Unique id of the pet Id int64 `json:"id"` // Name of the pet Name string `json:"name"` // Type of the pet Tag *string `json:"tag,omitempty"` } // Type definition for component schema "Pets" type Pets []Pet ``` It's best to define objects under `/components` field in the schema, since those will be turned into named Go types. If you use inline types in your handler definitions, we will generate inline, anonymous Go types, but those are more tedious to deal with since you will have to redeclare them at every point of use. For each element in the `paths` map in OpenAPI, we will generate a Go handler function in an interface object. Here is the generated Go interface for our Echo server. ```go type ServerInterface interface { // (GET /pets) FindPets(ctx echo.Context, params FindPetsParams) error // (POST /pets) AddPet(ctx echo.Context) error // (DELETE /pets/{id}) DeletePet(ctx echo.Context, id int64) error // (GET /pets/{id}) FindPetById(ctx echo.Context, id int64) error } ``` These are the functions which you will implement yourself in order to create a server conforming to the API specification. Normally, all the arguments and parameters are stored on the `echo.Context` in handlers, so we do the tedious work of unmarshalling the JSON automatically, simply passing values into your handlers. Notice that `FindPetById` takes a parameter `id int64`. All path arguments will be passed as arguments to your function, since they are mandatory. Remaining arguments can be passed in headers, query arguments or cookies. Those will be written to a `params` object. Look at the `FindPets` function above, it takes as input `FindPetsParams`, which is defined as follows: ```go // Parameters object for FindPets type FindPetsParams struct { Tags *[]string `json:"tags,omitempty"` Limit *int32 `json:"limit,omitempty"` } ``` The HTTP query parameter `limit` turns into a Go field named `Limit`. It is passed by pointer, since it is an optional parameter. If the parameter is specified, the pointer will be non-`nil`, and you can read its value. If you changed the OpenAPI specification to make the parameter required, the `FindPetsParams` structure will contain the type by value: ```go type FindPetsParams struct { Tags *[]string `json:"tags,omitempty"` Limit int32 `json:"limit"` } ``` ### Registering handlers There are a few ways of registering your http handler based on the type of server generated i.e. `-generate server` or `-generate chi-server`
Echo Code generated using `-generate server`. The usage of `Echo` is out of scope of this doc, but once you have an echo instance, we generate a utility function to help you associate your handlers with this autogenerated code. For the pet store, it looks like this: ```go func RegisterHandlers(router codegen.EchoRouter, si ServerInterface) { wrapper := ServerInterfaceWrapper{ Handler: si, } router.GET("/pets", wrapper.FindPets) router.POST("/pets", wrapper.AddPet) router.DELETE("/pets/:id", wrapper.DeletePet) router.GET("/pets/:id", wrapper.FindPetById) } ``` The wrapper functions referenced above contain generated code which pulls parameters off the `Echo` request context, and unmarshals them into Go objects. You would register the generated handlers as follows: ```go func SetupHandler() { var myApi PetStoreImpl // This implements the pet store interface e := echo.New() petstore.RegisterHandlers(e, &myApi) ... } ```
Chi Code generated using `-generate chi-server`. ```go type PetStoreImpl struct {} func (*PetStoreImpl) GetPets(w http.ResponseWriter, r *http.Request) { // Implement me } func SetupHandler() { var myApi PetStoreImpl r := chi.NewRouter() r.Mount("/", Handler(&myApi)) } ```
Gin Code generated using `-generate gin`. The usage of `gin` is out of scope of this doc, but once you have an gin instance, we generate a utility function to help you associate your handlers with this autogenerated code. For the pet store, it looks like this: ```go // RegisterHandlersWithOptions creates http.Handler with additional options func RegisterHandlersWithOptions(router *gin.Engine, si ServerInterface, options GinServerOptions) *gin.Engine { wrapper := ServerInterfaceWrapper{ Handler: si, HandlerMiddlewares: options.Middlewares, } router.GET(options.BaseURL+"/pets", wrapper.FindPets) router.POST(options.BaseURL+"/pets", wrapper.AddPet) router.DELETE(options.BaseURL+"/pets/:id", wrapper.DeletePet) router.GET(options.BaseURL+"/pets/:id", wrapper.FindPetByID) return router } ``` ```go import ( "github.com/gin-gonic/gin" "github.com/deepmap/oapi-codegen/examples/petstore-expanded/gin/api" middleware "github.com/deepmap/oapi-codegen/pkg/gin-middleware" ) type PetStoreImpl struct {} func (*PetStoreImpl) GetPets(w http.ResponseWriter, r *http.Request) { // Implement me } func SetupHandler() { var myApi PetStoreImpl r := gin.Default() r.Use(middleware.OapiRequestValidator(swagger)) r = api.RegisterHandlers(r, petStore) } ```
net/http [Chi](https://github.com/go-chi/chi) is 100% compatible with `net/http` allowing the following with code generated using `-generate chi-server`. ```go type PetStoreImpl struct {} func (*PetStoreImpl) GetPets(w http.ResponseWriter, r *http.Request) { // Implement me } func SetupHandler() { var myApi PetStoreImpl http.Handle("/", Handler(&myApi)) } ``` Alternatively, [Gorilla](https://github.com/gorilla/mux) is also 100% compatible with `net/http` and can be generated with `-generate gorilla`.
#### Strict server generation oapi-codegen also supports generating RPC inspired strict server, that will parse request bodies and encode responses. The main points of this code is to automate some parsing, abstract user code from server specific code, and also to force user code to comply with the schema. It supports binding of `application/json` and `application/x-www-form-urlencoded` to a struct, for `multipart` requests it generates a `multipart.Reader`, which can be used to either manually iterating over parts or using `runtime.BindMultipart` function to bind the form to a struct. All other content types are represented by a `io.Reader` interface. To form a response simply return one of the generated structs with corresponding status code and content type. For example, to return a status code 200 JSON response for a AddPet use the `AddPet200JSONResponse` struct which will set the correct Content-Type header, status code and will marshal the response data. You can also return an error, that will cause an `Internal Server Error` response. Short example: ```go type PetStoreImpl struct {} func (*PetStoreImpl) GetPets(ctx context.Context, request GetPetsRequestObject) (GetPetsResponseObject, error) { var result []Pet // Implement me return GetPets200JSONResponse(result), nil } ``` For a complete example see [`examples/petstore-expanded/strict`](https://github.com/deepmap/oapi-codegen/tree/master/examples/petstore-expanded/strict). Code is generated with a configuration flag `generate: strict-server: true` along with any other server (echo, chi, gin and gorilla are supported). The generated strict wrapper can then be used as an implementation for `ServerInterface`. Setup example: ```go func SetupHandler() { var myApi PetStoreImpl myStrictApiHandler := api.NewStrictHandler(myApi, nil) e := echo.New() petstore.RegisterHandlers(e, &myStrictApiHandler) } ``` Strict server also has its own middlewares. It can access to both request and response structs, as well as raw request\response data. It can be used for logging the parsed request\response objects, transforming go errors into response structs, authorization, etc. Note that middlewares are server-specific. #### Additional Properties in type definitions [OpenAPI Schemas](https://swagger.io/specification/#schemaObject) implicitly accept `additionalProperties`, meaning that any fields provided, but not explicitly defined via properties on the schema are accepted as input, and propagated. When unspecified, the `additionalProperties` field is assumed to be `true`. Additional properties are tricky to support in Go with typing, and require lots of boilerplate code, so in this library, we assume that `additionalProperties` defaults to `false` and we don't generate this boilerplate. If you would like an object to accept `additionalProperties`, specify a schema for `additionalProperties`. Say we declared `NewPet` above like so: ```yaml NewPet: required: - name properties: name: type: string tag: type: string additionalProperties: type: string ``` The Go code for `NewPet` would now look like this: ```go // NewPet defines model for NewPet. type NewPet struct { Name string `json:"name"` Tag *string `json:"tag,omitempty"` AdditionalProperties map[string]string `json:"-"` } ``` The additionalProperties, of type `string` become `map[string]string`, which maps field names to instances of the `additionalProperties` schema. ```go // Getter for additional properties for NewPet. Returns the specified // element and whether it was found func (a NewPet) Get(fieldName string) (value string, found bool) {...} // Setter for additional properties for NewPet func (a *NewPet) Set(fieldName string, value string) {...} // Override default JSON handling for NewPet to handle additionalProperties func (a *NewPet) UnmarshalJSON(b []byte) error {...} // Override default JSON handling for NewPet to handle additionalProperties func (a NewPet) MarshalJSON() ([]byte, error) {...}w ``` There are many special cases for `additionalProperties`, such as having to define types for inner fields which themselves support additionalProperties, and all of them are tested via the [`internal/test/components`](https://github.com/deepmap/oapi-codegen/tree/master/internal/test/components) schemas and tests. Please look through those tests for more usage examples. #### oneOf/anyOf/allOf support - `oneOf` and `anyOf` are implemented using delayed parsing with the help of `json.RawMessage`. The following schema will result in a type that has methods such as `AsCat`, `AsDog`, `FromCat`, `FromDog`, `MergeCat`, `MergeDog`. If the schema also includes a discriminator the generated code will also have methods such as `Discriminator`, `ValueByDiscriminator` and will force discriminator value in `From` methods. ```yaml schema: oneOf: - $ref: '#/components/schemas/Cat' - $ref: '#/components/schemas/Dog' ``` - `allOf` is supported, by taking the union of all the fields in all the component schemas. This is the most useful of these operations, and is commonly used to merge objects with an identifier, as in the `petstore-expanded` example. ## Generated Client Boilerplate Once your server is up and running, you probably want to make requests to it. If you're going to do those requests from your Go code, we also generate a client which is conformant with your schema to help in marshaling objects to JSON. It uses the same types and similar function signatures to your request handlers. The interface for the pet store looks like this: ```go // The interface specification for the client above. type ClientInterface interface { // FindPets request FindPets(ctx context.Context, params *FindPetsParams, reqEditors ...RequestEditorFn) (*http.Response, error) // AddPet request with JSON body AddPet(ctx context.Context, body NewPet, reqEditors ...RequestEditorFn) (*http.Response, error) // DeletePet request DeletePet(ctx context.Context, id int64, reqEditors ...RequestEditorFn) (*http.Response, error) // FindPetById request FindPetById(ctx context.Context, id int64, reqEditors ...RequestEditorFn) (*http.Response, error) } ``` A Client object which implements the above interface is also generated: ```go // Client which conforms to the OpenAPI3 specification for this service. type Client struct { // The endpoint of the server conforming to this interface, with scheme, // https://api.deepmap.com for example. Server string // HTTP client with any customized settings, such as certificate chains. Client http.Client // A callback for modifying requests which are generated before sending over // the network. RequestEditors []func(ctx context.Context, req *http.Request) error } ``` Each operation in your OpenAPI spec will result in a client function which takes the same arguments. It's difficult to handle any arbitrary body that Swagger supports, so we've done some special casing for bodies, and you may get more than one function for an operation with a request body. 1. If you have more than one request body type, meaning more than one media type, you will have a generic handler of this form: AddPet(ctx context.Context, contentType string, body io.Reader) 2. If you have only a JSON request body, you will get: AddPet(ctx context.Context, body NewPet) 3. If you have multiple request body types, which include a JSON type you will get two functions. We've chosen to give the JSON version a shorter name, as we work with JSON and don't want to wear out our keyboards. AddPet(ctx context.Context, body NewPet) AddPetWithBody(ctx context.Context, contentType string, body io.Reader) The Client object above is fairly flexible, since you can pass in your own `http.Client` and a request editing callback. You can use that callback to add headers. In our middleware stack, we annotate the context with additional information such as the request ID and function tracing information, and we use the callback to propagate that information into the request headers. Still, we can't foresee all possible usages, so those functions call through to helper functions which create requests. In the case of the pet store, we have: ```go // Request generator for FindPets func NewFindPetsRequest(server string, params *FindPetsParams) (*http.Request, error) {...} // Request generator for AddPet with JSON body func NewAddPetRequest(server string, body NewPet) (*http.Request, error) {...} // Request generator for AddPet with non-JSON body func NewAddPetRequestWithBody(server string, contentType string, body io.Reader) (*http.Request, error) {...} // Request generator for DeletePet func NewDeletePetRequest(server string, id int64) (*http.Request, error) {...} // Request generator for FindPetById func NewFindPetByIdRequest(server string, id int64) (*http.Request, error) {...} ``` You can call these functions to build an `http.Request` from Go objects, which will correspond to your request schema. They map one-to-one to the functions on the client, except that we always generate the generic non-JSON body handler. There are some caveats to using this code. - exploded, form style query arguments, which are the default argument format in OpenAPI 3.0 are undecidable. Say that I have two objects, one composed of the fields `(name=bob, id=5)` and another which has `(name=shoe, color=brown)`. The first parameter is named `person` and the second is named `item`. The default marshaling style for query args would result in `/path/?name=bob,id=5&name=shoe,color=brown`. In order to tell what belongs to which object, we'd have to look at all the parameters and try to deduce it, but we're lazy, so we didn't. Don't use exploded form style arguments if you're passing around objects which have similar field names. If you used unexploded form parameters, you'd have `/path/?person=name,bob,id,5&item=name,shoe,color,brown`, which an be parsed unambiguously. - Parameters can be defined via `schema` or via `content`. Use the `content` form for anything other than trivial objects, they can marshal to arbitrary JSON structures. When you send them as cookie (`in: cookie`) arguments, we will URL encode them, since JSON delimiters aren't allowed in cookies. ## Using SecurityProviders If you generate client-code, you can use some default-provided security providers which help you to use the various OpenAPI 3 Authentication mechanism. ```go import ( "github.com/deepmap/oapi-codegen/pkg/securityprovider" ) func CreateSampleProviders() error { // Example BasicAuth // See: https://swagger.io/docs/specification/authentication/basic-authentication/ basicAuthProvider, basicAuthProviderErr := securityprovider.NewSecurityProviderBasicAuth("MY_USER", "MY_PASS") if basicAuthProviderErr != nil { panic(basicAuthProviderErr) } // Example BearerToken // See: https://swagger.io/docs/specification/authentication/bearer-authentication/ bearerTokenProvider, bearerTokenProviderErr := securityprovider.NewSecurityProviderBearerToken("MY_TOKEN") if bearerTokenProviderErr != nil { panic(bearerTokenProviderErr) } // Example ApiKey provider // See: https://swagger.io/docs/specification/authentication/api-keys/ apiKeyProvider, apiKeyProviderErr := securityprovider.NewSecurityProviderApiKey("query", "myApiKeyParam", "MY_API_KEY") if apiKeyProviderErr != nil { panic(apiKeyProviderErr) } // Example providing your own provider using an anonymous function wrapping in the // InterceptoFn adapter. The behaviour between the InterceptorFn and the Interceptor interface // are the same as http.HandlerFunc and http.Handler. customProvider := func(req *http.Request, ctx context.Context) error { // Just log the request header, nothing else. log.Println(req.Header) return nil } // Exhaustive list of some defaults you can use to initialize a Client. // If you need to override the underlying httpClient, you can use the option // // WithHTTPClient(httpClient *http.Client) // client, clientErr := NewClient("https://api.deepmap.com", WithRequestEditorFn(apiKeyProvider.Intercept)) return nil } ``` ## Extensions `oapi-codegen` supports the following extended properties: - `x-go-type`: specifies Go type name. It allows you to specify the type name for a schema, and will override any default value. This extended property isn't supported in all parts of OpenAPI, so please refer to the spec as to where it's allowed. Swagger validation tools will flag incorrect usage of this property. - `x-go-name`: specifies Go field name. It allows you to specify the field name for a schema, and will override any default value. This extended property isn't supported in all parts of OpenAPI, so please refer to the spec as to where it's allowed. Swagger validation tools will flag incorrect usage of this property. - `x-go-type-name`: This property allows for assigning a Go type name to some part of a schema, such as generating a type name for an anonymous object inside another object, or renaming an enum. It differs from `x-go-type`, in that it doesn't completely replace some type reference, but simply names it. - `x-go-json-ignore`: sets tag to `-` to ignore the field in json completely. - `x-oapi-codegen-extra-tags`: adds extra Go field tags to the generated struct field. This is useful for interfacing with tag based ORM or validation libraries. The extra tags that are added are in addition to the regular json tags that are generated. If you specify your own `json` tag, you will override the default one. ```yaml components: schemas: Object: properties: name: type: string x-oapi-codegen-extra-tags: tag1: value1 tag2: value2 ``` In the example above, field `name` will be declared as: ``` Name string `json:"name" tag1:"value1" tag2:"value2"` ``` - `x-go-type-import`: adds extra Go imports to your generated code. It can help you, when you want to choose your own import package for `x-go-type`. ```yaml schemas: Pet: properties: age: x-go-type: myuuid.UUID x-go-type-import: name: myuuid path: github.com/google/uuid ``` After code generation you will get this: ```go import ( ... myuuid "github.com/google/uuid" ) //Pet defines model for Pet. type Pet struct { Age *myuuid.UUID `json:"age,omitempty"` } ``` `name` is an optional parameter. Example: ```yaml components: schemas: Pet: properties: age: x-go-type: uuid.UUID x-go-type-import: path: github.com/google/uuid required: - age ``` After code generation you will get this result: ```go import ( "github.com/google/uuid" ) // Pet defines model for Pet. type Pet struct { Age uuid.UUID `json:"age"` } ``` - `x-enum-varnames`: supplies other enum names for the corresponding values. (alias: `x-enumNames`) ```yaml components: schemas: Object: properties: category: type: integer enum: [0, 1, 2] x-enum-varnames: - notice - warning - urgent ``` After code generation you will get this result: ```go // Defines values for ObjectCategory. const ( Notice ObjectCategory = 0 Urgent ObjectCategory = 2 Warning ObjectCategory = 1 ) // ObjectCategory defines model for Object.Category. type ObjectCategory int ``` ## Using `oapi-codegen` The default options for `oapi-codegen` will generate everything; client, server, type definitions and embedded swagger spec, but you can generate subsets of those via the `-generate` flag. It defaults to `types,client,server,spec`, but you can specify any combination of those. - `types`: generate all type definitions for all types in the OpenAPI spec. This will be everything under `#components`, as well as request parameter, request body, and response type objects. - `server`: generate the Echo server boilerplate. `server` requires the types in the same package to compile. - `chi-server`: generate the Chi server boilerplate. This code is dependent on that produced by the `types` target. - `fiber`: generate the Fiber server boilerplate. This code is dependent on that produced by the `types` target. - `client`: generate the client boilerplate. It, too, requires the types to be present in its package. - `spec`: embed the OpenAPI spec into the generated code as a gzipped blob. This is then usable with the `OapiRequestValidator`, or to be used by other methods that need access to the parsed OpenAPI specification - `skip-fmt`: skip running `goimports` on the generated code. This is useful for debugging the generated file in case the spec contains weird strings. - `skip-prune`: skip pruning unused components from the spec prior to generating the code. - `import-mapping`: specifies a map of references external OpenAPI specs to go Go include paths. Please see below. So, for example, if you would like to produce only the server code, you could run `oapi-codegen -generate types,server`. You could generate `types` and `server` into separate files, but both are required for the server code. `oapi-codegen` can filter paths base on their tags in the openapi definition. Use either `-include-tags` or `-exclude-tags` followed by a comma-separated list of tags. For instance, to generate a server that serves all paths except those tagged with `auth` or `admin`, use the argument, `-exclude-tags="auth,admin"`. To generate a server that only handles `admin` paths, use the argument `-include-tags="admin"`. When neither of these arguments is present, all paths are generated. `oapi-codegen` can filter schemas based on the option `--exclude-schemas`, which is a comma separated list of schema names. For instance, `--exclude-schemas=Pet,NewPet` will exclude from generation schemas `Pet` and `NewPet`. This allow to have a in the same package a manually defined structure or interface and refer to it in the openapi spec. Since `go generate` commands must be a single line, all the options above can make them pretty unwieldy, so you can specify all of the options in a configuration file via the `--config` option. Please see the test under [`/internal/test/externalref/`](https://github.com/deepmap/oapi-codegen/blob/master/internal/test/externalref/externalref.cfg.yaml) for an example. The structure of the file is as follows: ```yaml package: externalref generate: models: true embedded-spec: true import-mapping: ./packageA/spec.yaml: github.com/deepmap/oapi-codegen/internal/test/externalref/packageA ./packageB/spec.yaml: github.com/deepmap/oapi-codegen/internal/test/externalref/packageB output: externalref.gen.go output-options: skip-prune: true ``` Have a look at [`cmd/oapi-codegen/oapi-codegen.go`](https://github.com/deepmap/oapi-codegen/blob/master/cmd/oapi-codegen/oapi-codegen.go#L48) to see all the fields on the configuration structure. ### Import Mappings OpenAPI specifications may contain references to other OpenAPI specifications, and we need some additional information in order to be able to generate correct Go code. An external reference looks like this: $ref: ./some_spec.yaml#/components/schemas/Type We assume that you have already generated the boilerplate code for `./some_spec.yaml` using `oapi-codegen`, and you have a package which contains the generated code, let's call it `github.com/deepmap/some-package`. You need to tell `oapi-codegen` that `some_spec.yaml` corresponds to this package, and you would do it by specifying this command line argument: -import-mapping=./some_spec.yaml:github.com/deepmap/some-package This tells us that in order to resolve references generated from `some_spec.yaml` we need to import `github.com/deepmap/some-package`. You may specify multiple mappings by comma separating them in the form `key1:value1,key2:value2`. ## What's missing or incomplete This code is still young, and not complete, since we're filling it in as we need it. We've not yet implemented several things: - `patternProperties` isn't yet supported and will exit with an error. Pattern properties were defined in JSONSchema, and the `kin-openapi` Swagger object knows how to parse them, but they're not part of OpenAPI 3.0, so we've left them out, as support is very complicated. ## Making changes to code generation The code generator uses a tool to inline all the template definitions into code, so that we don't have to deal with the location of the template files. When you update any of the files under the `templates/` directory, you will need to regenerate the template inlines: go generate ./pkg/codegen/templates All this command does is inline the files ending in `.tmpl` into the specified Go file. Afterwards you should run `go generate ./...`, and the templates will be updated accordingly. Alternatively, you can provide custom templates to override built-in ones using the `-templates` flag specifying a path to a directory containing templates files. These files **must** be named identically to built-in template files (see `pkg/codegen/templates/*.tmpl` in the source code), and will be interpreted on-the-fly at run time. Example: $ ls -1 my-templates/ client.tmpl typedef.tmpl $ oapi-codegen \ -templates my-templates/ \ -generate types,client \ petstore-expanded.yaml When using the configuration file, it is possible to provide templates directly as text, as a local path, or as a URL. If the data provided to the configuration file is more than one line, the local path and URL checks will be ignored and will be treated as raw template text. If one line, the string will be used to check for a local file, followed by checking performing a HTTP GET request. If the file lookup returns any error other than not found, or the HTTP request returns a non 200 response code, the generator will error. ⚠️ Warning: If using urls that tracks against git repositories such as `raw.githubusercontent.com`, it is strongly encouraged to use a tag or a hash instead of a branch like `main`. Tracking a branch can lead to unexpected API drift, and loss of the ability to reproduce a build. Examples: ```yaml output: api.gen.go package: api output-options: user-templates: # using a local file client-with-responses.tmpl: /home/username/workspace/templatesProject/my-client-with-responses.tmpl # The following are referencing a versuion of the default # client-with-responses.tmpl file, but loaded in through # github's raw.githubusercontent.com. The general form # to use raw.githubusercontent.com is as follows # https://raw.githubusercontent.com////path/to/template/template.tmpl # using raw.githubusercontent.com with a hash client-with-responses.tmpl: https://raw.githubusercontent.com/deepmap/oapi-codegen/7b010099dcf1192b3bfaa3898b5f375bb9590ddf/pkg/codegen/templates/client-with-responses.tmpl # using raw.githubusercontent.com with a tag client-with-responses.tmpl: https://raw.githubusercontent.com/deepmap/oapi-codegen/v1.12.4/pkg/codegen/templates/client-with-responses.tmpl # using raw.githubusercontent.com with a branch client-with-responses.tmpl: https://raw.githubusercontent.com/deepmap/oapi-codegen/master/pkg/codegen/templates/client-with-responses.tmpl #This example is directly embedding the template into the config file. client-with-responses.tmpl: | // ClientWithResponses builds on ClientInterface to offer response payloads type ClientWithResponses struct { ClientInterface } ... # template shortened for brevity ``` Using the configuration file to load in templates **will** load in templates with names other than those defined by the built in templates. These user templates will not be called unless the user overrides a built in template to call them however.