new 'object' macro: specify lifetimes for context object

[5o50]

I'm trying to specify a lifetime for a Context object using the new juniper::object proc macro.

pub struct Context<'a> {
    pub datastore: &'a Datastore
}

impl<'a> juniper::Context for Context<'a> {}

impl<'a> Context<'a> {

    pub fn new(repo: &'a Repo) -> Context<'a> {
        Context {
            datastore: &repo.datastore
        }
    }
}

pub struct Query;

#[juniper::object(context = Context)] // ^^^^^^^ expected lifetime parameter under Context
impl Query {

    fn datastore_version(ctx: &Context) -> String {
        ctx.datastore.get_version()
    }
}

The error is on #[juniper::object(context = Context)] a lifetime specifier is expected for Context.
When trying #[juniper::object(context = Context<'a>)] a ^^ undeclared lifetime for <`a> is returned.

[theduke]

This is the same issue as #143. (See especially the very last comment there, and the whole discussion for an explanation)

Below is a solution that works with the new macro.

Note that this might break in the future if you want to switch to async.

pub struct DataStore;

pub struct Context<'a> {
    pub datastore: &'a DataStore
}

impl<'a> juniper::Context for Context<'a> {}

pub struct Query<'a> {
  marker: std::marker::PhantomData<&'a ()>,   
}

#[juniper::object(context = Context<'a>)]
impl<'a> Query<'a> {

    fn datastore_version(ctx: &Context<'a>) -> String {
        "lala".into()
    }
}


fn main() {
  let query = Query{ marker: std::marker::PhantomData };
}