Where is my GenesisConfig entry for my config storage? - substrate

Question

I'm trying to reconstruct the Sudo module's root key behaviour before I extend it. Following the v1 documentation on GenesisConfig, I have a config() storage variable in my decl_storage:
RootKey get(fn rootkey) config(): T::AccountId;
(in the node-template template.rs for now)
Yet, if I look at the macro-expanded output, I have no template item in the GenesisConfig struct, and I cannot put in an entry like the following in the chain_spec's testnet_genesis function
template: Some(TemplateConfig {
rootkey: root_key,
}),
Because I get a complaint about both template and TemplateConfig, even though both are supposed to be constructed by the macro expansion.
Edit: Specifically, if it add the above with a TemplateConfig item in the use runtime::{} list, I am informed:
error[E0432]: unresolved import `runtime::TemplateConfig`
--> node-template/src/chain_spec.rs:4:14
|
4 | SudoConfig, TemplateConfig, IndicesConfig, SystemConfig, WASM_BINARY, Signature
| ^^^^^^^^^^^^^^ no `TemplateConfig` in the root
error[E0560]: struct `node_template_runtime::GenesisConfig` has no field named `template`
--> node-template/src/chain_spec.rs:142:3
|
142 | template: Some(TemplateConfig {
| ^^^^^^^^ `node_template_runtime::GenesisConfig` does not have this field
|
= note: available fields are: `system`, `aura`, `grandpa`, `indices`, `balances`, `sudo`
I also don't see any template items in polkadot.js under storage, whereas I do see sudo's key().
What obvious thing am I missing?

Answer 1

When trying to set up the genesis configuration for a runtime module you need to do the following:
Make sure your runtime module has "configurable storage items". This could be as simple as setting config() in the decl_storage! macro, but could also be a bit more complicated as documented here: `decl_storage! - GenesisConfig.
decl_storage! {
trait Store for Module<T: Trait> as Sudo {
Key get(fn key) config(): T::AccountId;
//--------------^^^^^^^^---------------
}
}
This will generate a GenesisConfig in your module, which will be used in the next step.
Next you need to expose your module specific GenesisConfig struct to the rest of your runtime's genesis configuration by adding the Config/Config<T> item to your construct_runtime! macro. In this example, we use Config<T> because we are configuring a generic T::AccountId:
construct_runtime!(
pub enum Runtime where
Block = Block,
NodeBlock = opaque::Block,
UncheckedExtrinsic = UncheckedExtrinsic
{
//--snip--
TemplateModule: template::{Module, Call, Storage, Event<T>, Config<T>},
//----------------------------------------------------------^^^^^^^^^--
}
}
This will generate an alias to your module specific GenesisConfig object based on the name you configured for your module (name + Config). In this case, the name of the object will be TemplateModuleConfig.
Finally, you need to configure this storage item in the chain_spec.rs file. To do this, make sure to import the TemplateModuleConfig item:
use node_template_runtime::{
AccountId, AuraConfig, BalancesConfig, GenesisConfig, GrandpaConfig,
SudoConfig, IndicesConfig, SystemConfig, WASM_BINARY, Signature,
TemplateModuleConfig,
//--^^^^^^^^^^^^^^^^^^^^
};
And then configure your genesis information:
template: Some(TemplateModuleConfig {
key: root_key,
}),

Answer 2

It sounds like you're missing use TemplateConfig at the beginning of your chain_spec.rs file. Something like this https://github.com/substrate-developer-hub/substrate-node-template/blob/8fea1dc6dd0c5547117d022fd0d1bf49868ee548/src/chain_spec.rs#L4
If this is not your issue please supply the exact error you're getting, and optionally a link to the full code.