Trait odbc_api::parameter::Blob

source · [−]
pub unsafe trait Blob: HasDataType {
    fn c_data_type(&self) -> CDataType;

    fn size_hint(&self) -> Option<usize>;

    fn next_batch(&mut self) -> Result<Option<&[u8]>>;

    fn as_blob_param(&mut self) -> BlobParam<'_>
    where
        Self: Sized,
    { ... }
}
Expand description

A Blob can stream its contents to the database batch by batch and may therefore be used to transfer large amounts of data, exceeding the drivers capabilities for normal input parameters.

Safety

If a hint is implemented for blob_size it must be accurate before the first call to next_batch.

Required methods

CData type of the binary data returned in the batches. Likely to be either crate::sys::CDataType::Binary, crate::sys::CDataType::Char or crate::sys::CDataType::WChar.

Hint passed on to the driver regarding the combined size of all the batches. This hint is passed then the parameter is bound to the statement, so its meaning is only defined before the first call to next_batch. If None no hint about the total length of the batches is passed to the driver and the indicator will be set to crate::sys::DATA_AT_EXEC.

Retrieve the netxt batch of data from the source. Batches may not be empty. None indicates the last batch has been reached.

Provided methods

Convinience function. Same as calling self::BlobParam::new.

Implementors