Crate struct_builder

Derive builders for your structs.

Putting #[builder] on your struct will derive the builder pattern for it. A new “params” struct will be defined derived from that follow the builder pattern. The builder can be used to create the struct from only required fields (those without the Option type) and modify the content of the struct.

A struct builder enforces required fields to be specified and allows optional arguments to be specified post-construction. This is done by defining a “params” struct that the builder depends on to be initialized. This struct defines all the fields in the original struct that don’t have the “Option” type. Once the builder is initialized with the params, both required and optional fields can be updated by calling builder methods (using the identifiers with_<field>).

Examples

Using builder to build a request with named fields.

use struct_builder::builder;

#[builder]
#[derive(Debug, Clone, Ord, PartialOrd, Eq, PartialEq)]
pub struct CreateUserRequest<P> {
    pub email: String,
    pub first_name: Option<String>,
    pub last_name: Option<String>,
    pub age: Option<u64>,
    pub payload: P
}

// Inherits attributes and generics from `CreateUserRequest`
let params: CreateUserRequestParams<String> = CreateUserRequestParams {
    email: "john.doe@email.com".to_owned(),
    payload: "John Doe's User".to_owned()
};

let request = CreateUserRequest::builder(params)
    .with_first_name(Some("John".to_owned()))
    .with_age(Some(35))
    .build();

assert_eq!(request.email, "john.doe@email.com".to_owned());
assert_eq!(request.first_name, Some("John".to_owned()));
assert_eq!(request.last_name, None);
assert_eq!(request.age, Some(35));

Using builder to build a tuple (unnamed) struct.

use struct_builder::builder;

/// First, Middle, and Last names.
#[builder]
pub struct FullName(pub String, pub Option<String>, pub String);

let params = FullNameParams("John".to_owned(), "Doe".to_owned());

let request = FullName::builder(params)
    .with_1(Some("Harold".to_owned()))
    .build();

assert_eq!(request.0, "John".to_owned());
assert_eq!(request.1, Some("Harold".to_owned()));
assert_eq!(request.2, "Doe".to_owned());

Converting a params struct directly with no builder.

use struct_builder::builder;

#[builder]
pub struct CreateUserRequest {
    pub email: String,
    pub first_name: Option<String>,
    pub last_name: Option<String>,
}

let request = CreateUserRequest::from(CreateUserRequestParams {
    email: "john.doe@email.com".to_owned()
});

assert_eq!(request.email, "john.doe@email.com".to_owned());
assert_eq!(request.first_name, None);
assert_eq!(request.last_name, None);

Creating a builder directly

use struct_builder::builder;

#[builder]
pub struct CreateUserRequest {
    pub email: String,
    pub first_name: Option<String>,
    pub last_name: Option<String>,
}

let request = CreateUserRequest {
    email: "john.doe@email.com".to_owned(),
    first_name: Some("John".to_owned()),
    last_name: None
};

let rebuilt_request = CreateUserRequestBuilder::from(request)
    .with_last_name(Some("Doe".to_owned()))
    .build();

assert_eq!(rebuilt_request.email, "john.doe@email.com".to_owned());
assert_eq!(rebuilt_request.first_name, Some("John".to_owned()));
assert_eq!(rebuilt_request.last_name, Some("Doe".to_owned()));

Attribute Macros

builder

Derive the builder pattern for a struct.

Derive Macros

StructBuilderDeprecated