How to use serde_as with vec of my type?

[Magicloud]

Say

struct MyType;
impl Display for MyType {};
impl FromStr for MyType {};

#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
struct MyStruct {
  #[serde_as(as = "DisplayFromStr")] // How to make this line works?
  field: Vec<MyType>
}

Thanks.

[jonasbb]

Hi, as written, the code tries to use the Display an FromStr implementations of Vec to perform the serialization. These do not exist, which is why you see the error. What you want is to apply the DisplayFromStr conversion on each element of the Vec. You write this as:

#[serde_with::serde_as] // You also need to add this line in front of each struct/enum where you use serde_as
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
struct MyStruct {
    #[serde_as(as = "Vec<DisplayFromStr>")]
    field: Vec<MyType>,
}

Other container types (e.g., Option, BTreeMap, HashSet) work the same way, by using the collection type for the field and inside serde_as.

If you work with a type you defined (like in your example), you might also be interested in the two derive macros SerializeDisplay and DeserializeFromStr. They can be used instead of the derives from serde. This way MyType implements the necessary traits you can remove serde_as from MyStruct.

[Magicloud]

Simple like that? Cool!

Thanks for the answer.