Access runtime storage `OnEmpty` values from the client

Question

StateBackend::storage calls return None when the StorageKey is empty.

If OnEmpty was set, one can decode and parse the RuntimeMetadata to access the default value and fall back to it.

• Is there any alternative method to get a storage default value from the client?
• In other words, are OnEmpty values persisted exclusively on the RuntimeMetadata?

Answer 1

No, there is no way to get the storage default value. If you want something like this, you will need to make the default value "shareable" between the node and runtime.

struct MyType(u32);

const MY_TYPE_DEFAULT: u32 = 10;

impl Default for MyType {
    fn default() -> Self { Self(MY_TYPE_DEFAULT) }
}

Something like this. Then you can also just use MY_TYPE_DEFAULT in the node for example.