Accessing Accounts

Use ctx.accounts for typed fields, ctx.bumps for PDA seeds, and ctx.remaining_accounts for variable account lists passed after the fixed layout.

Recipe

pub fn route(ctx: Context<Route>) -> Result<()> {
    let bump = ctx.bumps.vault;
    let vault = &mut ctx.accounts.vault;
    for acc in ctx.remaining_accounts.iter() {
        require!(acc.owner == &crate::ID, MyError::BadRemaining);
    }
    Ok(())
}

When to reach for this: Handlers read or mutate validated accounts and optional extras.

Working Example

pub fn swap(ctx: Context<Swap>) -> Result<()> {
    let user = &ctx.accounts.user;
    let pool = &mut ctx.accounts.pool;
    let bump = ctx.bumps.pool;
 
    msg!("user: {}, pool bump: {}", user.key(), bump);
 
    for meta in ctx.remaining_accounts.iter() {
        let ai = meta.to_account_info();
        require!(ai.is_writable, SwapError::ReadonlyAccount);
    }
    Ok(())
}

What this demonstrates:

Account fields are references with lifetimes tied to Context
ctx.bumps.<name> matches seeds field name
remaining_accounts is a slice of AccountInfo
Use to_account_info() for CPI account metas

Deep Dive

Account Mutation

&mut Account<'info, T> serializes changes at end of instruction if the account was marked mut in constraints.

remaining_accounts

Clients append accounts after the IDL order. Document expected order and validate each entry.

Gotchas

remaining_accounts unvalidated - Critical vulnerability.. Fix: Check owner, discriminator, signer as needed.
Wrong bump name in ctx.bumps - Field name must match seeds account field.. Fix: Use exact struct field name.
Cloning AccountInfo unnecessarily - CU waste.. Fix: Pass references into CPI helpers.
Assuming remaining order from IDL - Only fixed accounts are in IDL.. Fix: Publish separate docs for extras.
Reading data before validation in other crate - Only applies to unchecked paths.. Fix: Keep validation in constraints first.

Alternatives

Alternative	Use When	Don't Use When
Explicit accounts vec in struct	Small fixed sets	Large dynamic routing
AccountLoader::load	Zero-copy reads	Standard Account<T>
Sysvar accounts in struct	Clock, rent	remaining_accounts for rare sysvars

FAQs

What Anchor version is assumed?

0.32.1 throughout this section.

Can a PDA be a Signer in accounts struct?

No. Use seeds constraints and CPI signing.

Where is bump stored?

In your account struct field, set at initialization.

How do clients derive PDAs?

Use @solana/kit 7.0.0 with matching seed bytes.

What program id is used for PDAs?

Your Anchor program's declare_id address.

Do seeds include bump?

Not in seeds array; bump is separate parameter to find_program_address.

How to debug PDA failures?

Compare logged keys; verify seeds and program id client-side.

Are PDAs rent-exempt?

Yes when holding data; fund with payer on init.

Can one PDA sign multiple CPIs in one ix?

Yes with same signer seeds for each CPI.

Accessing Accounts

Use ctx.accounts for typed fields, ctx.bumps for PDA seeds, and ctx.remaining_accounts for variable account lists passed after the fixed layout.

Recipe

pub fn route(ctx: Context<Route>) -> Result<()> {
    let bump = ctx.bumps.vault;
    let vault = &mut ctx.accounts.vault;
    for acc in ctx.remaining_accounts.iter() {
        require!(acc.owner == &crate::ID, MyError::BadRemaining);
    }
    Ok(())
}

When to reach for this: Handlers read or mutate validated accounts and optional extras.

Working Example

pub fn swap(ctx: Context<Swap>) -> Result<()> {
    let user = &ctx.accounts.user;
    let pool = &mut ctx.accounts.pool;
    let bump = ctx.bumps.pool;
 
    msg!("user: {}, pool bump: {}", user.key(), bump);
 
    for meta in ctx.remaining_accounts.iter() {
        let ai = meta.to_account_info();
        require!(ai.is_writable, SwapError::ReadonlyAccount);
    }
    Ok(())
}

What this demonstrates:

Account fields are references with lifetimes tied to Context
ctx.bumps.<name> matches seeds field name
remaining_accounts is a slice of AccountInfo
Use to_account_info() for CPI account metas

Deep Dive

Account Mutation

&mut Account<'info, T> serializes changes at end of instruction if the account was marked mut in constraints.

remaining_accounts

Clients append accounts after the IDL order. Document expected order and validate each entry.

Gotchas

remaining_accounts unvalidated - Critical vulnerability.. Fix: Check owner, discriminator, signer as needed.
Wrong bump name in ctx.bumps - Field name must match seeds account field.. Fix: Use exact struct field name.
Cloning AccountInfo unnecessarily - CU waste.. Fix: Pass references into CPI helpers.
Assuming remaining order from IDL - Only fixed accounts are in IDL.. Fix: Publish separate docs for extras.
Reading data before validation in other crate - Only applies to unchecked paths.. Fix: Keep validation in constraints first.

Alternatives

Alternative	Use When	Don't Use When
Explicit accounts vec in struct	Small fixed sets	Large dynamic routing
AccountLoader::load	Zero-copy reads	Standard Account<T>
Sysvar accounts in struct	Clock, rent	remaining_accounts for rare sysvars

FAQs

What Anchor version is assumed?

0.32.1 throughout this section.

Can a PDA be a Signer in accounts struct?

No. Use seeds constraints and CPI signing.

Where is bump stored?

In your account struct field, set at initialization.

How do clients derive PDAs?

Use @solana/kit 7.0.0 with matching seed bytes.

What program id is used for PDAs?

Your Anchor program's declare_id address.

Do seeds include bump?

Not in seeds array; bump is separate parameter to find_program_address.

How to debug PDA failures?

Compare logged keys; verify seeds and program id client-side.

Are PDAs rent-exempt?

Yes when holding data; fund with payer on init.

Can one PDA sign multiple CPIs in one ix?

Yes with same signer seeds for each CPI.

Accessing Accounts

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Accessing Accounts