default-conversion-rs

Default conversion for structures with same fields of the same name

I discovered this way to do the same job of this crate: https://stackoverflow.com/questions/57477967/how-can-i-use-serde-to-serialize-a-struct-to-another-rust-data-structure

But apparently my way to do it with From is faster : https://github.com/serde-rs/json/issues/724

Why I created this ?

Some projects which use derive proc macros need separates structures with similar "structures" to make different things. For example :

• An API with input structures that have some same fields with the model.

Usage :

default-conversion = "0.1.0"

Example :

Developper code:

struct B {
    a: i32,
};

#[derive(IntoDefault)]
#[IntoStruct(B)]
struct InputB {
    a: i32,
};

struct A {
    a: String,
    b: i32,
    c: B
};

#[derive(IntoDefault)]
#[IntoStruct(A)]
struct InputA {
    a: String,
    b: i32,
    #[IntoType(B)]
    c: InputB
};

let a = InputA {
    a: String::from("test"),
    b: 2,
    c: InputB {
        a: 3
    }
};

let b = A::from(a);

Expanded code :

struct B {
    a: i32,
};

#[derive(IntoDefault)]
#[IntoStruct(B)]
struct InputB {
    a: i32,
};

impl From<InputB> for B {
    fn from(item: InputB) -> Self {
        B {
            a: item.a.into()
        }
    }
}

struct A {
    a: String,
    b: i32,
    c: B
};

#[derive(IntoDefault)]
#[IntoStruct(A)]
struct InputA {
    a: String,
    b: i32,
    #[IntoType(B)]
    c: InputB
};

impl From<InputA> for A {
    fn from(item: InputA) -> Self {
        A {
            a: item.a.into(),
            b: item.b.into(),
            c: item.c.into()
        }
    }
}

let a = InputA {
    a: String::from("test"),
    b: 2,
    c: InputB {
        a: 3
    }
};

let b = A::from(a);

Complete example in tests/basic_struct.rs

Explanations

Detailed explanations in docs (soon xd).

IntoDefault is the main derive macro to invoke the from implementation.

IntoStruct the attribute proc macro to define the type in which we want to implement the conversion. #[IntoStruct(TYPE_OF_STRUCT)]

Supported features:

• Conversion with primitive types.
• Conversion with complex types.
• Auto convert to Option or Object as needed.
• Conversion with vectors of different types

Next steps:

• Examples
• Better tests
• Docs