Factory Contracts

Factory contracts are contracts that create other contracts. They are useful for:

• Dividing your app into parts, each with different responsibilities.

• Extending the scope of your app by dynamically adding a piece of functionality.

• Managing different parts of the app from a single location, etc.

The Factory Contract Template is a good starting point for setting up your own factory contracts and experimenting with them.

Here are some examples of active projects that use factory contracts:

• SecretSwap, where a Factory contract creates a new Child contract for every new pair supported on the exchange. (Cosmwasm v0.10).

• SecretJack, where a Parent "Bank" Contract which manages the funds creates a single "Game" Contract which manages the game logic. (Cosmwasm v0.10).

How to create Factory contracts

After the child contract is stored on chain, you can instantiate child contracts from the factory in the following manner:

Cosmwasm v1

Assume the child contract expects the following instantiate message:

// example of an Instantiate Msg
#[derive(serde::Serialize, serde::Deserialize)]
pub struct OffspringInstantiateMsg {
    pub example_field: i32,
}

To instantiate the child contract, you can send a submessage from the parent with the child's instantiate message:

use cosmwasm_std::{SubMsg, Response};
use secret_toolkit::utils::{InitCallback};

const OFFSPRING_INSTANTIATE_REPLY_ID: u64 = 1;

// Implement InitCallback on the OffsprintInit message
// to be able to convert it to cosmosMsg
impl InitCallback for OffspringInstantiateMsg {
    const BLOCK_SIZE: usize = BLOCK_SIZE;
}

// populate the message
let init_msg = OffspringInstantiateMsg {
    example_field: 1,
};

// build a submessage from the offspring init message
let init_submsg = SubMsg::reply_always(
    initmsg.to_cosmos_msg(
        "example_label".to_string(), // label for offspring contract
        1,                           // offspring code id
        "d519793af2...".to_string(), // offspring code hash
        None,                        // funds amount
    )?,
    OFFSPRING_INSTANTIATE_REPLY_ID,
);

// then build the response with the submessage
Ok(Response::new().add_submessage(init_submsg))

If you don't care about the reply, you can send a regular message instead:

let init_cosmos_msg = initmsg.to_cosmos_msg(
    "example_label".to_string(), // label for offspring contract
    1,                           // offspring code id
    "d519793af2...".to_string(), // offspring code hash
    None,                        // funds amount
)?;

Ok(Response::new().add_message(init_cosmos_msg))

Cosmwasm v0.10

Assume the child contract expects the following instantiate message:

// example of an Instantiate Msg
#[derive(serde::Serialize, serde::Deserialize)]
pub struct OffspringInstantiateMsg {
    pub example_field: i32,
}

To instantiate the child contract, send a message on the parent's response:

use cosmwasm_std::{CosmosMsg, WasmMsg};
use secret_toolkit::utils::{InitCallback};

// Implement InitCallback on the OffsprintInit message
// to be able to convert it to cosmosMsg
impl InitCallback for OffspringInstantiateMsg {
    const BLOCK_SIZE: usize = BLOCK_SIZE;
}

let messages = vec![
    initmsg.to_cosmos_msg(
        "example_label".to_string(), // label for offspring contract
        1,                           // offspring code id
        "d519793af2...".to_string(), // offspring code hash
        None,                        // funds amount
    )?,
]);

// Then return the message from an entry point, for example on init:
Ok(InitResponse {
    messages,
    log: vec![],
})