Derive Macro utoipa::IntoParams

#[derive(IntoParams)]
{
    // Attributes available to this derive:
    #[param]
    #[into_params]
}

IntoParams derive macro.

This is #[derive] implementation for IntoParams trait.

Typically path parameters need to be defined within #[utoipa::path(...params(...))] section for the endpoint. But this trait eliminates the need for that when structs are used to define parameters. Still std::primitive and String path parameters or tuple style path parameters need to be defined within params(...) section if description or other than default configuration need to be given.

You can use the Rust’s own #[deprecated] attribute on field to mark it as deprecated and it will reflect to the generated OpenAPI spec.

#[deprecated] attribute supports adding additional details such as a reason and or since version but this is is not supported in OpenAPI. OpenAPI has only a boolean flag to determine deprecation. While it is totally okay to declare deprecated with reason #[deprecated = "There is better way to do this"] the reason would not render in OpenAPI spec.

IntoParams Container Attributes for #[into_params(...)]

The following attributes are available for use in on the container attribute #[into_params(...)] for the struct deriving IntoParams:

• names(...) Define comma seprated list of names for unnamed fields of struct used as a path parameter.
• style = ... Defines how all parameters are serialized by ParameterStyle. Default values are based on parameter_in attribute.
• parameter_in = ... = Defines where the parameters of this field are used with a value from openapi::path::ParameterIn. There is no default value, if this attribute is not supplied, then the value is determined by the parameter_in_provider in IntoParams::into_params().

IntoParams Field Attributes for #[param(...)]

The following attributes are available for use in the #[param(...)] on struct fields:

• style = ... Defines how the parameter is serialized by ParameterStyle. Default values are based on parameter_in attribute.
• explode Defines whether new parameter=value pair is created for each parameter withing object or array.
• allow_reserved Defines whether reserved characters :/?#[]@!$&'()*+,;= is allowed within value.
• example = ... Can be literal value, method reference or json!(...). ¹ Given example will override any example in underlying parameter type.
• value_type = ... Can be used to override default type derived from type of the field used in OpenAPI spec. This is useful in cases where the default type does not correspond to the actual type e.g. when any third-party types are used which are not ToSchemas nor primitive types. Value can be any Rust type what normally could be used to serialize to JSON or custom type such as Object. Object will be rendered as generic OpenAPI object.
• inline If set, the schema for this field’s type needs to be a ToSchema, and the schema definition will be inlined.

Note! #[into_params(...)] is only supported on unnamed struct types to declare names for the arguments.

Use names to define name for single unnamed argument.

#[derive(IntoParams)]
#[into_params(names("id"))]
struct Id(u64);

Use names to define names for multiple unnamed arguments.

#[derive(IntoParams)]
#[into_params(names("id", "name"))]
struct IdAndName(u64, String);

Examples

Demonstrate IntoParams usage with resolving Path and Query parameters for get_pet endpoint. ²

use actix_web::{get, HttpResponse, Responder};
use actix_web::web::{Path, Query};
use serde::Deserialize;
use serde_json::json;
use utoipa::IntoParams;

#[derive(Deserialize, IntoParams)]
struct PetPathArgs {
    /// Id of pet
    id: i64,
    /// Name of pet
    name: String,
}

#[derive(Deserialize, IntoParams)]
struct Filter {
    /// Age filter for pets
    #[deprecated]
    #[param(style = Form, explode, allow_reserved, example = json!([10]))]
    age: Option<Vec<i32>>,
}

#[utoipa::path(
    params(PetPathArgs, Filter),
    responses(
        (status = 200, description = "success response")
    )
)]
#[get("/pet/{id}/{name}")]
async fn get_pet(pet: Path<PetPathArgs>, query: Query<Filter>) -> impl Responder {
    HttpResponse::Ok().json(json!({ "id": pet.id }))
}

Demonstrate IntoParams usage with the #[into_params(...)] container attribute to be used as a path query, and inlining a schema query field:

use serde::Deserialize;
use utoipa::{IntoParams, ToSchema};

#[derive(Deserialize, ToSchema)]
#[serde(rename_all = "snake_case")]
enum PetKind {
    Dog,
    Cat,
}

#[derive(Deserialize, IntoParams)]
#[into_params(style = Form, parameter_in = Query)]
struct PetQuery {
    /// Name of pet
    name: Option<String>,
    /// Age of pet
    age: Option<i32>,
    /// Kind of pet
    #[param(inline)]
    kind: PetKind
}

#[utoipa::path(
    get,
    path = "/get_pet",
    params(PetQuery),
    responses(
        (status = 200, description = "success response")
    )
)]
async fn get_pet(query: PetQuery) {
    // ...
}

Override String with i64 using value_type attribute.

#[derive(IntoParams)]
#[into_params(parameter_in = Query)]
struct Filter {
    #[param(value_type = i64)]
    id: String,
}

Override String with Object using value_type attribute. Object will render as type: object in OpenAPI spec.

#[derive(IntoParams)]
#[into_params(parameter_in = Query)]
struct Filter {
    #[param(value_type = Object)]
    id: String,
}

You can use a generic type to override the default type of the field.

#[derive(IntoParams)]
#[into_params(parameter_in = Query)]
struct Filter {
    #[param(value_type = Option<String>)]
    id: String
}

You can even overide a Vec with another one.

#[derive(IntoParams)]
#[into_params(parameter_in = Query)]
struct Filter {
    #[param(value_type = Vec<i32>)]
    id: Vec<String>
}

We can override value with another ToSchema.

#[derive(ToSchema)]
struct Id {
    value: i64,
}

#[derive(IntoParams)]
#[into_params(parameter_in = Query)]
struct Filter {
    #[param(value_type = Id)]
    id: String
}

---

1. json feature need to be enabled for json!(...) type to work. ↩

2. Feature actix_extras need to be enabled ↩