Struct SqliteValue 

pub struct SqliteValue(/* private fields */);

An owned handle to a sqlite3_value.

Note: Decoding is Stateful

The sqlite3_value interface reserves the right to be stateful:

Other interfaces might change the datatype for an sqlite3_value object. For example, if the datatype is initially SQLITE_INTEGER and sqlite3_value_text(V) is called to extract a text value for that integer, then subsequent calls to sqlite3_value_type(V) might return SQLITE_TEXT. Whether or not a persistent internal datatype conversion occurs is undefined and may change from one release of SQLite to the next.

Thus, this type is !Sync and SqliteValueRef is !Send and !Sync to prevent data races.

Additionally, this statefulness means that the return values of sqlite3_value_bytes() and sqlite3_value_blob() could be invalidated by later calls to other sqlite3_value* methods.

To prevent undefined behavior from accessing dangling pointers, this type (and any SqliteValueRef instances created from it) remembers when it was used to decode a borrowed &[u8] or &str and returns an error if it is used to decode any other type.

To bypass this error, you must prove that no outstanding borrows exist.

This may be done in one of a few ways:

• If you hold mutable access, call Self::reset_borrow() which resets the borrowed state.
• If you have an immutable reference, call Self::clone() to get a new instance with no outstanding borrows.
• If you hold a SqliteValueRef, call SqliteValueRef::to_owned() to get a new SqliteValue with no outstanding borrows.

This is only necessary if using the same SqliteValue or SqliteValueRef to decode multiple different types. The vast majority of use-cases employing once-through decoding should not have to worry about this.

Implementations

impl SqliteValue

pub fn reset_borrow(&mut self)

Prove that there are no outstanding borrows of this instance.

Call this after decoding a borrowed &[u8] or &str to reset the internal borrowed state and allow decoding of other types.

pub fn try_clone(&self) -> Result<SqliteValue, SqliteError>

Call sqlite3_value_dup() to create a new instance of this type.

Returns an error if the call returns a null pointer, indicating that SQLite was unable to allocate the additional memory required.

Non-panicking version of Self::clone().

Trait Implementations

impl Clone for SqliteValue

fn clone(&self) -> SqliteValue

Call sqlite3_value_dup() to create a new instance of this type.

Panics

If sqlite3_value_dup() returns a null pointer, indicating an out-of-memory condition.

See Self::try_clone() for a non-panicking version.

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

Performs copy-assignment from source.

impl Value for SqliteValue

type Database = Sqlite

fn as_ref(&self) -> SqliteValueRef<'_>

Get this value as a reference.

fn type_info(&self) -> Cow<'_, SqliteTypeInfo>

Get the type information for this value.

fn is_null(&self) -> bool

Returns true if the SQL value is NULL.

fn decode<'r, T>(&'r self) -> T

where T: Decode<'r, Self::Database> + Type<Self::Database>,

Decode this single value into the requested type.

fn decode_unchecked<'r, T>(&'r self) -> T

where T: Decode<'r, Self::Database>,

Decode this single value into the requested type.

fn try_decode<'r, T>(&'r self) -> Result<T, Error>

where T: Decode<'r, Self::Database> + Type<Self::Database>,

Decode this single value into the requested type.

fn try_decode_unchecked<'r, T>(&'r self) -> Result<T, Error>

where T: Decode<'r, Self::Database>,

Decode this single value into the requested type.