Error defining BoundedVec as a Pallet Storage the trait `Decode` is not implemented for `sp_runtime::BoundedVec

Question

I have a StorageValue defined as follows

    #[pallet::storage]
    #[pallet::getter(fn reg_students)]
    pub type RegStudents<T: Config> =
        StorageValue<_, BoundedVec<StudentId, T::MaxStudents>, ValueQuery>;

and the types are defined as follows

#[pallet::constant]
type MaxStudents: Get<u16>;

pub type StudentId = u32;

I am getting the following error compiling

62  | pub trait StorageValue<T: FullCodec> {
    |                           ^^^^^^^^^ required by this bound in `frame_support::StorageValue::get`
help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement
    |
103 |     #[pallet::storage where sp_runtime::BoundedVec<u32, <T as pallet::Config>::MaxStudents>: Decode]

StorageValue<_, BoundedVec<StudentId, T::MaxStudents>, ValueQuery>;
    |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Decode` is not implemented for `sp_runtime::BoundedVec<u32, <T as pallet::Config>::MaxStudents>`

Answer 1

Please check the impl.

https://paritytech.github.io/substrate/master/src/sp_core/bounded/bounded_vec.rs.html#45

It requires Get<u32>.

Try:

#[pallet::constant]
type MaxStudents: Get<u32>;