Serialization Basics

10 examples to get you started with Account Serialization - 7 basic and 3 intermediate.

Prerequisites

• Borsh familiarity from Rust for Solana.

Basic Examples

1. Borsh account struct

Serialize structured state into account data.

#[derive(BorshSerialize, BorshDeserialize)]
pub struct Config { pub fee_bps: u16 }

• Default choice for small/medium state.
• Easy versioning with extra fields at end.
• Compute cost scales with size.

2. Account size constant

Predeclare space for create_account.

impl Config { pub const LEN: usize = 2; }

• Mismatch causes serialize failure.
• Include discriminator bytes in total.
• Anchor InitSpace calculates automatically.

3. Discriminator prefix

Tag account type to prevent confusion.

pub const DISCRIMINATOR: [u8; 8] = [0xC0, 0xFF, 0xEE, 0x00, 0x00, 0x00, 0x00, 0x01];

• Anchor uses 8-byte hash discriminators.
• Check before deserialize.
• Different types must differ.

4. Deserialize guard

Validate length and discriminator first.

if data.len() < Config::LEN { return Err(ProgramError::InvalidAccountData); }

• Never deserialize untrusted accounts.
• Map errors to InvalidAccountData.
• Reject trailing garbage for fixed layouts.

5. Zero-copy when large

Use Pod for big fixed arrays.

#[repr(C)]
#[derive(Pod, Zeroable, Clone, Copy)]
pub struct Book { pub bids: [u64; 256] }

• Avoids parse loop CUs.
• Requires repr(C) discipline.
• See zero-copy accounts page.

6. Instruction vs account

Instructions often Borsh; accounts may be hybrid.

// ix: enum Instruction { Update { val: u64 } }

• Ix data is ephemeral per tx.
• Account data persists on-chain.
• Keep schemas separate.

7. Rent and size

Larger accounts need more lamports.

let rent = Rent::get()?.minimum_balance(Config::LEN);

• Rent-exempt minimum required.
• realloc increases needed rent.
• Users pay at create/realloc.

Intermediate Examples

8. Version byte migration

First byte indicates schema version.

pub enum Version { V1 = 1, V2 = 2 }

• Migration ix reads V1 writes V2.
• Never assume all accounts upgraded.
• Support both during rollout.

Related: Data Versioning & Migration

9. realloc grow

Expand account when schema grows.

// CPI realloc + rent transfer then new fields

• Needs payer lamports.
• Zero new bytes or explicit init.
• See realloc article.

Related: realloc & Growing Accounts

10. Space calculation

Sum discriminator + fields + padding.

pub const SPACE: usize = 8 + Config::LEN;

• Document formula in code.
• Test on host with serialize.
• Anchor init space macro.

Related: Space Calculation

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.

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