Struct rusqlite::blob::Blob[][src]

pub struct Blob<'conn> { /* fields omitted */ }
Expand description

feature = "blob" Handle to an open BLOB. See rusqlite::blob documentation for in-depth discussion.

Implementations

Write buf to self starting at write_start, returning an error if write_start + buf.len() is past the end of the blob.

If an error is returned, no data is written.

Note: the blob cannot be resized using this function – that must be done using SQL (for example, an UPDATE statement).

Note: This is part of the positional I/O API, and thus takes an absolute position write to, instead of using the internal position that can be manipulated by the std::io traits.

Unlike the similarly named FileExt::write_at function (from std::os::unix), it’s always an error to perform a “short write”.

An alias for write_at provided for compatibility with the conceptually equivalent std::os::unix::FileExt::write_all_at function from libstd:

Read as much as possible from offset to offset + buf.len() out of self, writing into buf. On success, returns the number of bytes written.

If there’s insufficient data in self, then the returned value will be less than buf.len().

See also Blob::raw_read_at, which can take an uninitialized buffer, or Blob::read_at_exact which returns an error if the entire buf is not read.

Note: This is part of the positional I/O API, and thus takes an absolute position to read from, instead of using the internal position that can be manipulated by the std::io traits. Consequently, it does not change that value either.

Read as much as possible from offset to offset + buf.len() out of self, writing into buf. On success, returns the portion of buf which was initialized by this call.

If there’s insufficient data in self, then the returned value will be shorter than buf.

See also Blob::read_at, which takes a &mut [u8] buffer instead of a slice of MaybeUninit<u8>.

Note: This is part of the positional I/O API, and thus takes an absolute position to read from, instead of using the internal position that can be manipulated by the std::io traits. Consequently, it does not change that value either.

Equivalent to Blob::read_at, but returns a BlobSizeError if buf is not fully initialized.

Equivalent to Blob::raw_read_at, but returns a BlobSizeError if buf is not fully initialized.

Move a BLOB handle to a new row.

Failure

Will return Err if the underlying SQLite BLOB reopen call fails.

Return the size in bytes of the BLOB.

Return the current size in bytes of the BLOB.

Return true if the BLOB is empty.

Close a BLOB handle.

Calling close explicitly is not required (the BLOB will be closed when the Blob is dropped), but it is available so you can get any errors that occur.

Failure

Will return Err if the underlying SQLite close call fails.

Trait Implementations

Executes the destructor for this type. Read more

Read data from a BLOB incrementally. Will return Ok(0) if the end of the blob has been reached.

Failure

Will return Err if the underlying SQLite read call fails.

Like read, except that it reads into a slice of buffers. Read more

🔬 This is a nightly-only experimental API. (can_vector)

Determines if this Reader has an efficient read_vectored implementation. Read more

🔬 This is a nightly-only experimental API. (read_initializer)

Determines if this Reader can work with buffers of uninitialized memory. Read more

Read all bytes until EOF in this source, placing them into buf. Read more

Read all bytes until EOF in this source, appending them to buf. Read more

Read the exact number of bytes required to fill buf. Read more

Creates a “by reference” adapter for this instance of Read. Read more

Transforms this Read instance to an Iterator over its bytes. Read more

Creates an adapter which will chain this stream with another. Read more

Creates an adapter which will read at most limit bytes from it. Read more

Seek to an offset, in bytes, in BLOB.

Rewind to the beginning of a stream. Read more

🔬 This is a nightly-only experimental API. (seek_stream_len)

Returns the length of this stream (in bytes). Read more

Returns the current seek position from the start of the stream. Read more

Write data into a BLOB incrementally. Will return Ok(0) if the end of the blob has been reached; consider using Write::write_all(buf) if you want to get an error if the entirety of the buffer cannot be written.

This function may only modify the contents of the BLOB; it is not possible to increase the size of a BLOB using this API.

Failure

Will return Err if the underlying SQLite write call fails.

Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more

Like write, except that it writes from a slice of buffers. Read more

🔬 This is a nightly-only experimental API. (can_vector)

Determines if this Writer has an efficient write_vectored implementation. Read more

Attempts to write an entire buffer into this writer. Read more

🔬 This is a nightly-only experimental API. (write_all_vectored)

Attempts to write multiple buffers into this writer. Read more

Writes a formatted string into this writer, returning any error encountered. Read more

Creates a “by reference” adapter for this instance of Write. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Performs the conversion.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.