Struct structsy::PrepareOpen

pub struct PrepareOpen { /* private fields */ }

Prepare open of a structsy file, with migrations possibilities

Implementations

impl PrepareOpen

pub fn migrate<S, D>(&self) -> SRes<()>where S: Persistent, D: Persistent + From<S>,

Migrate an existing persistent struct to a new struct.

In structsy the name and order of the fields matter for the persistence, so each change need to migrate existing data from existing struct layout to the new struct.

Example

use structsy::Structsy;
use structsy_derive::Persistent;
#[derive(Persistent)]
struct PersonV0 {
    name:String,
}

#[derive(Persistent)]
struct PersonV1 {
    name:String,
    surname:String,
}

impl From<PersonV0> for PersonV1 {
    fn from(f: PersonV0)  -> Self {
        PersonV1 {
            name: f.name,
            surname: "Doe".to_string(),
        }
    }
}


let prepare = Structsy::prepare_open("path/to/file.stry")?;
prepare.migrate::<PersonV0,PersonV1>()?;
let stry = prepare.open()?;
stry.define::<PersonV1>()?;

pub fn open(self) -> SRes<Structsy>

Open a structsy instance from a prepare context.

Example

use structsy::Structsy;
let prepare = Structsy::prepare_open("path/to/file.stry")?;
let stry = prepare.open()?;