Go Substrate Code Generator

A tool that generates boilerplate code for substrate-based chains (calls, storage access, events, etc) using go-substrate-rpc-client.

This uses the metadata Json RPC provided by substrate-based chains, which you can get by doing:

curl -L -X POST -H "Content-Type: application/json" -d '{"id":1, "jsonrpc":"2.0", "method": "state_getMetadata"}' https://rpc.polkadot.io > polkadot-meta.json

Just replace rpc.polkadot.io with your own server.

Installation

Clone the repo, run go install ./... and make sure it's on your path.

Using go generate

Make a submodule in your go project. Place a metadata.json and the following mymodule.go file in it

//go:generate go-substrate-gen metadata.json "github.com/my/package/mymodule"

package mymodule

Then run go generate ./... and it'll generate code for each pallet in the mymodule directory.

Calling manually

go-substrate-gen meta.json "github.com/my/package/submodule/for/code" 

Getting Metadata

There is code included under json-gen to fetch a human-readable version of the json from a locally running substrate node in dev mode. View the readme for instructions.

Architecture and Design

Please read the documentation, which describes the received metadata's structure, and also gives an overview of the code's structure.

Calling code

Example for pallet_balances

// Transfer some liquid free balance to another account.
//
// `transfer` will set the `FreeBalance` of the sender and receiver.
// If the sender's account is below the existential deposit as a result
// of the transfer, the account will be reaped.
//
// The dispatch origin for this call must be `Signed` by the transactor.
//
// # <weight>
// - Dependent on arguments but not critical, given proper implementations for input config
//   types. See related functions below.
// - It contains a limited number of reads and writes internally and no complex
//   computation.
//
// Related functions:
//
//   - `ensure_can_withdraw` is always called internally but has a bounded complexity.
//   - Transferring balances to accounts that did not exist before will cause
//     `T::OnNewAccount::on_new_account` to be called.
//   - Removing enough funds from an account will trigger `T::DustRemoval::on_unbalanced`.
//   - `transfer_keep_alive` works the same way as `transfer`, but has an additional check
//     that the transfer will not kill the origin account.
// ---------------------------------
// - Origin account is already in memory, so no DB operations for them.
// # </weight>
func MakeTransferCall(dest0 *MultiAddress, value1 *types.UCompact) (types.Call, error) {...}
...

Storage code

// Make a storage key for Account
//  The Balances pallet example of storing the balance of an account.
//
//  # Example
//
//  
//   impl pallet_balances::Config for Runtime {
//     type AccountStore = StorageMapShim<Self::Account<Runtime>, frame_system::Provider<Runtime>, AccountId, Self::AccountData<Balance>>
//   }
//  
//
//  You can also store the balance of an account in the `System` pallet.
//
//  # Example
//
//  ```nocompile
//   impl pallet_balances::Config for Runtime {
//    type AccountStore = System
//   }
//  ```
//
//  But this comes with tradeoffs, storing account balances in the system pallet stores
//  `frame_system` data alongside the account data contrary to storing account balances in the
//  `Balances` pallet, which uses a `StorageMap` to store balances data only.
//  NOTE: This is only used in the case that this pallet is used to store balances.
func MakeAccountStorageKey(byteArray0 [32]byte) (types.StorageKey, error) {...}

func GetAccount(state *state.State, bhash types.Hash, byteArray0 [32]byte) (ret AccountData, err error) {...}
...

Types

// Generated pallet_balances_AccountData
type AccountData struct {
	// Field 0 with TypeId=6
	Free types.U128
	// Field 1 with TypeId=6
	Reserved types.U128
	// Field 2 with TypeId=6
	MiscFrozen types.U128
	// Field 3 with TypeId=6
	FeeFrozen types.U128
}

// Generated SpRuntimeMultiaddressMultiAddress with id=188
type MultiAddress struct {
	IsId              bool
	AsIdField0        [32]byte
	IsIndex           bool
	AsIndexField0     struct{}
	IsRaw             bool
	AsRawField0       []byte
	IsAddress32       bool
	AsAddress32Field0 [32]byte
	IsAddress20       bool
	AsAddress20Field0 [20]byte
}

func (ty MultiAddress) Encode(encoder scale.Encoder) (err error) {...}

func (ty *MultiAddress) Decode(decoder scale.Decoder) (err error) {...}