Storage and get methods

Summary: In the previous steps, we learned how to use the Blueprint and its project structure.

подсказка

If you're stuck on any of the examples, you can find the original template project with all modifications made during this guide here.

Almost all smart contracts need to store their data between transactions. This guide explains standard ways to manage storage for smart contracts and how to use get methods to access it from outside the blockchain.

Smart contract storage operations

FunC

There are two main instructions that provide access to smart contract storage:

• get_data() returning the current storage cell.
• set_data() setting storage cell.

Tolk

There are two main instructions that provide access to smart contract storage:

• getContractData() returning current storage Cell.
• setContractData() setting storage Cell.

Let's examine the Cell structure to understand how to manage contract storage:

Cell structure

TON Blockchain uses a data structure called Cell as the fundamental unit for storing data. Cells are the building blocks of smart contract data and have the following characteristics:

• A Cell can store up to 1023 bits (approximately 128 bytes) of data.
• A Cell can reference up to 4 other Cells (children).
• A Cell is immutable once created.

You can think of a Cell as the following structure:

// Conceptual representation of a Cell
interface Cell {
  bits: BitString; // Up to 1023 bits
  refs: Cell[];    // Up to 4 child cells
}

Implementation

Let's modify our smart contract by following the standard steps described in the previous Blueprint overview section.

Step 1: edit smart contract code

If manually serializing and deserializing the storage cell becomes inconvenient, a common practice is to define two wrapper methods that handle this logic. If you haven't modified the smart contract code, it should include the following lines in the /contracts/hello_world.fc:

FunC

/contracts/hello_world.fc

global int ctx_id;
global int ctx_counter;

;; load_data populates storage variables using stored data
() load_data() impure {
    var ds = get_data().begin_parse();

    ctx_id = ds~load_uint(32);
    ctx_counter = ds~load_uint(32);

    ds.end_parse();
}

;; save_data stores storage variables as a cell into persistent storage
() save_data() impure {
    set_data(
        begin_cell()
            .store_uint(ctx_id, 32)
            .store_uint(ctx_counter, 32)
            .end_cell()
    );
}

Tolk

/contracts/hello_world.tolk

global ctxID: int;
global ctxCounter: int;

// loadData populates storage variables from persistent storage
fun loadData() {
    var ds = getContractData().beginParse();

    ctxID = ds.loadUint(32);
    ctxCounter = ds.loadUint(32);

    ds.assertEndOfSlice();
}

// saveData stores storage variables as a cell into persistent storage
fun saveData() {
    setContractData(
        beginCell()
        .storeUint(ctxID, 32)
        .storeUint(ctxCounter, 32)
        .endCell());
}

Managing storage

Let's modify our example slightly by exploring another common storage management approach in smart contract development:

Rather than initializing global variables, we'll:

1. Pass storage members as parameters via save_data(members...).
2. Retrieve them using (members...) = get_data().
3. Move the global variables ctx_id and ctx_counter into the method bodies.

Also let's add an additional 256-bit integer to our storage as ctx_counter_ext global variable. The modified implementation should appear as follows:

FunC

/contracts/hello_world.fc

(int, int, int) load_data() {
    var ds = get_data().begin_parse();

    int ctx_id = ds~load_uint(32);
    int ctx_counter = ds~load_uint(32);
    int ctx_counter_ext = ds~load_uint(256);

    ds.end_parse();

    return (ctx_id, ctx_counter, ctx_counter_ext);
}

() save_data(int ctx_id, int ctx_counter, int ctx_counter_ext) impure {
    set_data(
        begin_cell()
            .store_uint(ctx_id, 32)
            .store_uint(ctx_counter, 32)
            .store_uint(ctx_counter_ext, 256)
        .end_cell()
    );
}

Tolk

/contracts/hello_world.tolk

// load_data retrieves variables from TVM storage cell
// impure because of writting into global variables
fun loadData(): (int, int, int) {
    var ds = getContractData().beginParse();

    // id is required to be able to create different instances of counters
    // since addresses in TON depend on the initial state of the contract
    var ctxID = ds.loadUint(32);
    var ctxCounter = ds.loadUint(32);
    var ctxCounterExt = ds.loadUint(256);

    ds.assertEndOfSlice();

    return (ctxID, ctxCounter, ctxCounterExt);
}

// saveData stores storage variables as a cell into persistent storage
fun saveData(ctxID: int, ctxCounter: int, ctxCounterExt: int) {
    setContractData(
        beginCell()
        .storeUint(ctxID, 32)
        .storeUint(ctxCounter, 32)
        .storeUint(ctxCounterExt, 256)
        .endCell()
    );
}

Remember to:

1. Remove the global variables ctx_id and ctx_counter
2. Update the function usage by copying storage members locally as shown:

FunC

/contracts/hello_world.fc

;; load_data() on:
var (ctx_id, ctx_counter, ctx_counter_ext) = load_data();

;; save_data() on:
save_data(ctx_id, ctx_counter, ctx_counter_ext);

Tolk

/contracts/hello_world.tolk

// loadData() on:
var (ctxID, ctxCounter, ctxCounterExt) = loadData();

// saveData() on:
saveData(ctxID, ctxCounter, ctxCounterExt);

Get methods

The main purpose of get methods is to provide an external read access to storage data through a convenient interface — primarily to extract the information needed for preparing transactions. Let's add a getter function that returns both the main and extended counter values stored in the smart contract.

FunC

/contracts/hello_world.fc

(int, int) get_counters() method_id {
    var (_, ctx_counter, ctx_counter_ext) = load_data();
    return (ctx_counter, ctx_counter_ext);
}

Tolk

/contracts/hello_world.tolk

get get_counters(): (int, int) {
    var (_, ctxCounter, ctxCounterExt) = loadData();
    return (ctxCounter, ctxCounterExt);
}

And don’t forget to update the variables in the get methods to match the unpacking from load_data().

FunC

/contracts/hello_world.fc

int get_counter() method_id {
var (_, ctx_counter, _) = load_data();
return ctx_counter;
}

int get_id() method_id {
var (ctx_id, _, _) = load_data();
return ctx_id;
}

Tolk

/contracts/hello_world.tolk

get currentCounter(): int {
var (ctxID, ctxCounter, ctxCounterExt) = loadData();
return ctxCounter;
}

get initialId(): int {
var (ctxID, ctxCounter, ctxCounterExt) = loadData();
return ctxID;
}

And that's all! In practice, all get methods follow this straightforward pattern and require no additional complexity. Remember, you can ignore return values using the _ placeholder syntax.

Here's the final smart contract implementation:

FunC

/contracts/hello_world.fc

#include "imports/stdlib.fc";

const op::increase = "op::increase"c; ;; create an opcode from string using the "c" prefix, this results in 0x7e8764ef opcode in this case

(int, int, int) load_data() {
    var ds = get_data().begin_parse();

    int ctx_id = ds~load_uint(32);
    int ctx_counter = ds~load_uint(32);
    int ctx_counter_ext = ds~load_uint(256);

    ds.end_parse();

    return (ctx_id, ctx_counter, ctx_counter_ext);
}

() save_data(int ctx_id, int ctx_counter, int ctx_counter_ext) impure {
    set_data(
        begin_cell()
            .store_uint(ctx_id, 32)
            .store_uint(ctx_counter, 32)
            .store_uint(ctx_counter_ext, 256)
        .end_cell()
    );
}

() recv_internal(int my_balance, int msg_value, cell in_msg_full, slice in_msg_body) impure {
    if (in_msg_body.slice_empty?()) { ;; ignore all empty messages
        return ();
    }

    slice cs = in_msg_full.begin_parse();
    int flags = cs~load_uint(4);
    if (flags & 1) { ;; ignore all bounced messages
        return ();
    }

    var (ctx_id, ctx_counter, ctx_counter_ext) = load_data(); ;; here we populate the storage variables

    int op = in_msg_body~load_uint(32); ;; by convention, the first 32 bits of incoming message is the op
    int query_id = in_msg_body~load_uint(64); ;; also by convention, the next 64 bits contain the "query id", although this is not always the case

    if (op == op::increase) {
        int increase_by = in_msg_body~load_uint(32);
        ctx_counter += increase_by;
        save_data(ctx_id, ctx_counter, ctx_counter_ext);
        return ();
    }

    throw(0xffff); ;; if the message contains an op that is not known to this contract, we throw
}

int get_counter() method_id {
    var (_, ctx_counter, _) = load_data();
    return ctx_counter;
}

int get_id() method_id {
    var (ctx_id, _, _) = load_data();
    return ctx_id;
}

(int, int) get_counters() method_id {
    var (_, ctx_counter, ctx_counter_ext) = load_data();
    return (ctx_counter, ctx_counter_ext);
}

Tolk

/contracts/hello_world.tolk

const OP_INCREASE = 0x7e8764ef;  // arbitrary 32-bit number, equal to OP_INCREASE in wrappers/CounterContract.ts

fun loadData(): (int, int, int) {
    var ds = getContractData().beginParse();

    var ctxID = ds.loadUint(32);
    var ctxCounter = ds.loadUint(32);
    var ctxCounterExt = ds.loadUint(256);

    ds.assertEndOfSlice();

    return (ctxID, ctxCounter, ctxCounterExt);
}

fun saveData(ctxID: int, ctxCounter: int, ctxCounterExt: int) {
    setContractData(
        beginCell()
        .storeUint(ctxID, 32)
        .storeUint(ctxCounter, 32)
        .storeUint(ctxCounterExt, 256)
        .endCell()
    );
}

fun onInternalMessage(myBalance: int, msgValue: int, msgFull: cell, msgBody: slice) {
    if (msgBody.isEndOfSlice()) { // ignore all empty messages
        return;
    }

    var cs: slice = msgFull.beginParse();
    val flags = cs.loadMessageFlags();
    if (isMessageBounced(flags)) { // ignore all bounced messages
        return;
    }

    var (ctxID, ctxCounter, ctxCounterExt) = loadData(); // here we populate the storage variables

    val op = msgBody.loadMessageOp(); // by convention, the first 32 bits of incoming message is the op
    val queryID = msgBody.loadMessageQueryId(); // also by convention, the next 64 bits contain the "query id", although this is not always the case

    if (op == OP_INCREASE) {
        val increaseBy = msgBody.loadUint(32);
        ctxCounter += increaseBy;
        saveData(ctxID, ctxCounter, ctxCounterExt);
        return;
    }

    throw 0xffff; // if the message contains an op that is not known to this contract, we throw
}

get currentCounter(): int {
    var (ctxID, ctxCounter, ctxCounterExt) = loadData();
    return ctxCounter;
}

get initialId(): int {
    var (ctxID, ctxCounter, ctxCounterExt) = loadData();
    return ctxID;
}

get get_counters(): (int, int) {
    var (_, ctxCounter, ctxCounterExt) = loadData();
    return (ctxCounter, ctxCounterExt);
}

Before proceeding, verify your changes by compiling the smart contract:

npx blueprint build

The expected output should look like this:

Build script running, compiling HelloWorld

✅ Compiled successfully! Cell BOC result:

{
  "hash": "310e49288a12dbc3c0ff56113a3535184f76c9e931662ded159e4a25be1fa28b",
  "hashBase64": "MQ5JKIoS28PA/1YROjU1GE92yekxZi3tFZ5KJb4foos=",
  "hex": "b5ee9c7241010e0100d0000114ff00f4a413f4bcf2c80b01020120020d02014803080202ce0407020120050600651b088831c02456f8007434c0cc1caa42644c383c0040f4c7f4cfcc4060841fa1d93beea5f4c7cc28163c00b817c12103fcbc2000153b513434c7f4c7f4fff4600017402c8cb1fcb1fcbffc9ed548020120090a000dbe7657800b60940201580b0c000bb5473e002b70000db63ffe002606300072f2f800f00103d33ffa40fa00d31f30c8801801cb055003cf1601fa027001cb6a82107e8764ef01cb1f12cb3f5210cb1fc970fb0013a012f0020844ca0a"
}

✅ Wrote compilation artifact to build/HelloWorld.compiled.json

This means the HelloWorld contract was successfully compiled. A hash was generated, and the compiled code was saved to build/HelloWorld.compiled.json.

Step 2: update wrapper

Next, we'll update our wrapper class to align with the new storage layout and get method. We need to:

1. Modify the helloWorldConfigToCell function.
2. Update the HelloWorldConfig type.
3. Ensure proper storage initialization during contract creation.
4. Include the 256-bit ctxCounterExt field we added earlier.

These changes will maintain consistency with our smart contract modifications.

/wrappers/HelloWorld.ts

// @version TypeScript 5.8.3
export type HelloWorldConfig = {
    id: number;
    ctxCounter: number;
    ctxCounterExt: bigint;
};

export function helloWorldConfigToCell(config: HelloWorldConfig): Cell {
    return beginCell()
        .storeUint(config.id, 32)
        .storeUint(config.ctxCounter, 32)
        .storeUint(config.ctxCounterExt, 256)
    .endCell();
}

Next, implement a method to call the new get_counters smart contract get method, which retrieves both counter values in a single request:

/HelloWorld.ts

async getCounters(provider: ContractProvider) : Promise<[number, bigint]> {
    const result = await provider.get('get_counters', []);
    const counter = result.stack.readNumber();
    const counterExt = result.stack.readBigNumber();

    return [counter, counterExt]
}

Step 3: update tests

Finally, let's test the new functionality using our updated wrapper:

1. Initialize the contract storage by creating a helloWorldConfig with test values.
2. Execute each get method to retrieve stored data.
3. Validate that values match the initial configuration.

Example implementation:

/tests/HelloWorld.spec.ts

// @version TypeScript 5.8.3
import { Blockchain, SandboxContract, TreasuryContract } from '@ton/sandbox';
import { Cell, toNano} from '@ton/core';
import { HelloWorld } from '../wrappers/HelloWorld';
import '@ton/test-utils';
import { compile } from '@ton/blueprint';

describe('HelloWorld', () => {
    let code: Cell;

    beforeAll(async () => {
        code = await compile('HelloWorld');
    });

    let blockchain: Blockchain;
    let deployer: SandboxContract<TreasuryContract>;
    let helloWorld: SandboxContract<HelloWorld>;

    beforeEach(async () => {
        blockchain = await Blockchain.create();

        helloWorld = blockchain.openContract(
            HelloWorld.createFromConfig(
                {
                    id: 0,
                    ctxCounter: 0,
                    ctxCounterExt: 0n,
                },
                code
            )
        );

        deployer = await blockchain.treasury('deployer');

        const deployResult = await helloWorld.sendDeploy(deployer.getSender(), toNano('1.00'));

        expect(deployResult.transactions).toHaveTransaction({
            from: deployer.address,
            to: helloWorld.address,
            deploy: true,
            success: true,
        });
    });

    it('should correctly initialize and return the initial data', async () => {
        // Define the expected initial values (same as in beforeEach)
        const expectedConfig = {
            id: 0,
            counter: 0,
            counterExt: 0n
        };

        // Log the initial configuration values before verification
        console.log('Initial configuration values (before deployment):');
        console.log('- ID:', expectedConfig.id);
        console.log('- Counter:', expectedConfig.counter);
        console.log('- CounterExt:', expectedConfig.counterExt);

        console.log('Retrieved values after deployment:');
        // Verify counter value
        const counter = await helloWorld.getCounter();
        console.log('- Counter:', counter);
        expect(counter).toBe(expectedConfig.counter);

        // Verify ID value
        const id = await helloWorld.getID();
        console.log('- ID:', id);
        expect(id).toBe(expectedConfig.id);

        // Verify counterExt
        const [_, counterExt] = await helloWorld.getCounters();
        console.log('- CounterExt', counterExt);
        expect(counterExt).toBe(expectedConfig.counterExt);
    });

    // ... previous tests
});

Now you can run the new test script with this command:

npx blueprint test

The expected output should look like this:

# "custom log messages"

 PASS  tests/HelloWorld.spec.ts
  HelloWorld
    ✓ should correctly initialize and return the initial data (431 ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        3.591 s, estimated 6 s

Next step

You’ve written your first smart contract using FunC or Tolk, tested it, and explored how storage and get methods work.

Now it’s time to move on to one of the most important parts of smart contracts —processing messages: sending and receiving them.

Processing messages

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