Runtime API to collect values in StorageMap

Question

I'm trying to retrieve all values in my StorageMap defined as such in my pallet:

#[pallet::storage]
#[pallet::getter(fn submitted_tasks)]
pub type SubmittedTasks<T: Config> =
    StorageMap<_, Blake2_128Concat, B3Hash, Task<T>, OptionQuery>;

from my runtime api (in runtime/src/lib.rs), currently defined as such and not working:

impl pallet_submitter_runtime_api::SubmitterRuntimeApi<Block> for Runtime {
    fn get_submitted_tasks() -> Vec<Vec<u8>> {
        // This macro generated getter only allows me to query one item.
        SubmitterModule::submitted_tasks();

        // This does not compile due to associated item not found
        SubmitterModule::SubmittedTasks.iter_values().collect();
        
        vec![]
    }
}

Now from my understanding, if i use the macro generated getter, it's only possible to query one value from the StorageMap, however I would like to iterate over all values to collect them. How can I achieve this?

Note: the return type will be the vector of encoded Tasks for simplicity

Answer 1

This should work. I added a comment above the line in the code to explain what happens there.

impl pallet_submitter_runtime_api::SubmitterRuntimeApi<Block> for Runtime {
    fn get_submitted_tasks() -> Vec<Vec<u8>> {
        // This macro generated getter only allows me to query one item.
        SubmitterModule::submitted_tasks();

        // The return type is Vec<Vec<u8>>, but your StorageMap stores 
        // as value a `Task<T>`. So, you need to first encode this value
        // and then you can collect into a vector. You probably just missed
        // the explicit type to make Rust happy.
        pallet_submitter::SubmittedTasks::<Runtime>::iter_values().map(|v| v.encode()).collect::<Vec<Vec<_>>>();
    }
}