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State

type State<A> = {
  fetch: Promise<undefined | A>;
  fromAppState: A;
  get: A;
  getAndRequireEquals: A;
  requireEquals: void;
  requireEqualsIf: void;
  requireNothing: void;
  set: void;
};

Defined in: lib/mina/v1/state.ts:86

Gettable and settable state that can be checked for equality.

Type Parameters​

A​

A

Methods​

fetch()​

fetch(): Promise<undefined | A>;

Defined in: lib/mina/v1/state.ts:57

Asynchronously fetch the on-chain state. This is intended for getting the state outside a smart contract.

Returns​

Promise<undefined | A>

fromAppState()​

fromAppState(appState: Field[]): A;

Defined in: lib/mina/v1/state.ts:84

Get the state from the raw list of field elements on a zkApp account, for example:

let myContract = new MyContract(address);
let account = Mina.getAccount(address);

let x = myContract.x.fromAppState(account.zkapp!.appState);

Parameters​

appState​

Field[]

Returns​

A

get()​

get(): A;

Defined in: lib/mina/v1/state.ts:44

Get the current on-chain state.

Caution: If you use this method alone inside a smart contract, it does not prove that your contract uses the current on-chain state. To successfully prove that your contract uses the current on-chain state, you must add an additional .requireEquals() statement or use .getAndRequireEquals():

let x = this.x.get();
this.x.requireEquals(x);

OR

let x = this.x.getAndRequireEquals();

Returns​

A

getAndRequireEquals()​

getAndRequireEquals(): A;

Defined in: lib/mina/v1/state.ts:49

Get the current on-chain state and prove it really has to equal the on-chain state, by adding a precondition which the verifying Mina node will check before accepting this transaction.

Returns​

A

requireEquals()​

requireEquals(a: A): void;

Defined in: lib/mina/v1/state.ts:62

Prove that the on-chain state has to equal the given state, by adding a precondition which the verifying Mina node will check before accepting this transaction.

Parameters​

a​

A

Returns​

void

requireEqualsIf()​

requireEqualsIf(condition: Bool, a: A): void;

Defined in: lib/mina/v1/state.ts:69

Require that the on-chain state has to equal the given state if the provided condition is true.

If the condition is false, this is a no-op. If the condition is true, this adds a precondition that the verifying Mina node will check before accepting this transaction.

Parameters​

condition​

Bool

a​

A

Returns​

void

requireNothing()​

requireNothing(): void;

Defined in: lib/mina/v1/state.ts:73

DANGER ZONE: Override the error message that warns you when you use .get() without adding a precondition.

Returns​

void

set()​

set(a: A): void;

Defined in: lib/mina/v1/state.ts:53

Set the on-chain state to a new value.

Parameters​

a​

A

Returns​

void