An Anchor validation constraint that asserts a field stored in one account matches the pubkey of another account in the instruction's accounts struct. For example, #[account(has_one = authority)] on a vault account verifies that vault.authority equals the authority account's key. Failing the check returns an Anchor error. has_one prevents unauthorized callers from passing arbitrary accounts for privileged roles.
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An Anchor validation constraint that asserts a field stored in one account matches the pubkey of another account in the instruction's accounts struct. For example, #[account(has_one = authority)] on a vault account verifies that vault.authority equals the authority account's key. Failing the check returns an Anchor error. has_one prevents unauthorized callers from passing arbitrary accounts for privileged roles.
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Anchor, local validators, explorers, SDKs, and testing workflows.
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has_one Constraint (Anchor) (has-one-constraint) Category: Developer Tools Definition: An Anchor validation constraint that asserts a field stored in one account matches the pubkey of another account in the instruction's accounts struct. For example, #[account(has_one = authority)] on a vault account verifies that vault.authority equals the authority account's key. Failing the check returns an Anchor error. has_one prevents unauthorized callers from passing arbitrary accounts for privileged roles. Related: Anchor Constraints, Insufficient Account Constraints, Authority
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Declarative validation rules on Anchor account fields. Key constraints: `#[account(mut)]` (writable), `#[account(init, payer=x, space=n)]` (create), `#[account(seeds=[...], bump)]` (PDA validation), `#[account(has_one=field)]` (field equality), `#[account(constraint = expr)]` (custom boolean), `#[account(close=target)]` (close and reclaim rent).
A broad vulnerability category in Anchor programs where the account struct's constraint annotations — such as has_one, constraint = expr, seeds, bump, mint, authority, and token::mint — are missing or incomplete, allowing callers to supply accounts that pass deserialization and ownership checks but violate the program's intended relationships. For example, omitting has_one = authority on a vault account means any account can be passed as the authority; omitting mint = token_account.mint on an SPL token account means a different mint's token account could be substituted. Thorough Anchor account structs should declare every meaningful relationship between accounts as a typed constraint.
A pubkey with administrative privileges over a resource—such as the mint authority (can mint tokens), freeze authority (can freeze accounts), upgrade authority (can upgrade a program), or the signer authorized to perform operations on a PDA-controlled account. Authority is a convention, not a runtime concept.
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Declarative validation rules on Anchor account fields. Key constraints: `#[account(mut)]` (writable), `#[account(init, payer=x, space=n)]` (create), `#[account(seeds=[...], bump)]` (PDA validation), `#[account(has_one=field)]` (field equality), `#[account(constraint = expr)]` (custom boolean), `#[account(close=target)]` (close and reclaim rent).
Anchor CLI commands for project lifecycle. `anchor init <name>` scaffolds a new project (program, tests, Anchor.toml). `anchor build` compiles to SBF and generates the IDL. `anchor test` builds, starts a local validator, deploys, and runs Mocha/Jest tests. `anchor deploy` deploys to the configured cluster. `anchor verify` checks deployed bytecode.
A major release (March 2025) of the Anchor framework introducing custom discriminators (overriding the default 8-byte discriminator to save transaction space), LazyAccount for on-demand deserialization to reduce compute costs, and stack memory optimizations for init constraints. Positioned as a major milestone on the roadmap toward v1.0.
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Declarative validation rules on Anchor account fields. Key constraints: `#[account(mut)]` (writable), `#[account(init, payer=x, space=n)]` (create), `#[account(seeds=[...], bump)]` (PDA validation), `#[account(has_one=field)]` (field equality), `#[account(constraint = expr)]` (custom boolean), `#[account(close=target)]` (close and reclaim rent).
A broad vulnerability category in Anchor programs where the account struct's constraint annotations — such as has_one, constraint = expr, seeds, bump, mint, authority, and token::mint — are missing or incomplete, allowing callers to supply accounts that pass deserialization and ownership checks but violate the program's intended relationships. For example, omitting has_one = authority on a vault account means any account can be passed as the authority; omitting mint = token_account.mint on an SPL token account means a different mint's token account could be substituted. Thorough Anchor account structs should declare every meaningful relationship between accounts as a typed constraint.
A pubkey with administrative privileges over a resource—such as the mint authority (can mint tokens), freeze authority (can freeze accounts), upgrade authority (can upgrade a program), or the signer authorized to perform operations on a PDA-controlled account. Authority is a convention, not a runtime concept.
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The most popular framework for building Solana programs in Rust. Anchor provides macros (#[program], #[account], #[derive(Accounts)]) that auto-generate boilerplate for account validation, serialization, discriminators, and error handling. It includes a CLI (anchor init/build/test/deploy), IDL generation, and TypeScript client generation. Reduces program code by ~80% compared to native development.
The Anchor macro applied to structs to define on-chain account data layouts. `#[account]` auto-derives Borsh serialization, adds an 8-byte discriminator prefix (SHA-256 of 'account:<Name>'), and implements space calculation. Optional attributes: `#[account(zero_copy)]` for zero-copy deserialization of large accounts.
The Anchor macro that defines the accounts struct for an instruction. Each field specifies an account with validation constraints. Account types include: `Account<'info, T>` (deserialized), `Signer<'info>` (must sign), `Program<'info, T>` (program reference), `SystemAccount<'info>`, and `UncheckedAccount<'info>` (no validation, use carefully).
Declarative validation rules on Anchor account fields. Key constraints: `#[account(mut)]` (writable), `#[account(init, payer=x, space=n)]` (create), `#[account(seeds=[...], bump)]` (PDA validation), `#[account(has_one=field)]` (field equality), `#[account(constraint = expr)]` (custom boolean), `#[account(close=target)]` (close and reclaim rent).