Struct TxOptions 

pub struct TxOptions { /* private fields */ }

What a transaction is opened with: the parts of transaction control the three engines do not agree on.

Defaults to “whatever the engine’s own default is” on every axis, so Transaction::begin_on_with with a default TxOptions sends exactly what Transaction::begin_on sends.

Implementations

impl TxOptions

pub const fn new() -> Self

No option set: the engine’s own defaults.

pub const fn isolation(self, level: Isolation) -> Self

Ask for an isolation level.

pub const fn access(self, mode: Access) -> Self

Ask for an access mode.

pub const fn read_only(self) -> Self

Shorthand for Access::ReadOnly.

pub const fn sqlite_begin(self, mode: SqliteBegin) -> Self

SQLite’s begin mode. An error on any other family.

pub const fn get_isolation(self) -> Option<Isolation>

The isolation level asked for, if any.

pub const fn get_access(self) -> Option<Access>

The access mode asked for, if any.

pub const fn get_sqlite_begin(self) -> Option<SqliteBegin>

The SQLite begin mode asked for, if any.

pub fn check(&self, family: Family) -> Result<(), ExecError>

Can this engine honour these options? Answers without opening a transaction — backends call it before checking a connection out, and callers can pre-flight a configuration with it.

pub fn plan(&self, family: Family) -> Result<Vec<String>, ExecError>

The exact statements Transaction::begin_on_with will run, in order, on the transaction’s own connection — or the error explaining why this engine cannot be asked for this.

Nothing here is inferred at run time from a server version; it is the documented grammar of each engine, and it is public so that “what does keelson actually send?” is answerable without a packet capture.

	PostgreSQL	MySQL / InnoDB	SQLite
READ UNCOMMITTED	refused (accepted by the server, run as READ COMMITTED)	yes	refused
READ COMMITTED	yes (default)	yes	refused
REPEATABLE READ	yes	yes (default)	refused
SERIALIZABLE	yes	yes	yes — SQLite’s only level
READ ONLY	yes	yes	refused (PRAGMA query_only is connection state)
SqliteBegin	refused	refused	yes

The rule behind every refusal: a level is accepted only when the engine runs the transaction at that level. Substituting a neighbouring level would satisfy the SQL standard (it permits running stricter than asked) and would still be a lie to the caller, who asked in order to get particular behaviour.

The match on Family is exhaustive on purpose: a new family cannot be added to this crate without deciding what it does here.

Trait Implementations

impl Clone for TxOptions

fn clone(&self) -> TxOptions

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for TxOptions

impl Debug for TxOptions

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for TxOptions

fn default() -> TxOptions

Returns the “default value” for a type.

impl Eq for TxOptions

impl From<Access> for TxOptions

fn from(mode: Access) -> Self

Converts to this type from the input type.

impl From<Isolation> for TxOptions

fn from(level: Isolation) -> Self

Converts to this type from the input type.

impl From<SqliteBegin> for TxOptions

fn from(mode: SqliteBegin) -> Self

Converts to this type from the input type.

impl Hash for TxOptions

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for TxOptions

fn eq(&self, other: &TxOptions) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for TxOptions