Struct odbc_api::parameter::VarBinary

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pub struct VarBinary<B> { /* private fields */ }

Expand description

Binds a byte array as Variadic sized binary data. It can not be used for columnar bulk fetches, but if the buffer type is stack allocated it can be utilized in row wise bulk fetches.

Meaningful instantiations of this type are:

self::VarBinarySlice - immutable borrowed parameter.
self::VarBinarySliceMut - mutable borrowed input / output parameter
self::VarBinaryArray - stack allocated owned input / output parameter
self::VarBinaryBox - heap allocated owned input /output parameter

Implementations

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impl VarBinary<Box<[u8 ], Global>>

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pub fn null() -> Self

Constructs a ‘missing’ value.

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pub fn from_vec(val: Vec<u8>) -> Self

Create an instance from a Vec.

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impl VarBinary where
B: Borrow<[u8 ]>,

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pub fn from_buffer(buffer: B, indicator: Indicator) -> Self

Creates a new instance from an existing buffer.

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pub fn as_bytes(&self) -> Option<&[u8 ]>

Valid payload of the buffer returned as slice or None in case the indicator is NULL_DATA.

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pub fn is_complete(&self) -> bool

Call this method to ensure that the entire field content did fit into the buffer. If you retrieve a field using crate::CursorRow::get_data, you can repeat the call until this method is false to read all the data.

use odbc_api::{CursorRow, parameter::VarBinaryArray, Error, handles::Statement};

fn process_large_binary<S: Statement>(
    col_index: u16,
    row: &mut CursorRow<S>
) -> Result<(), Error>{
    let mut buf = VarBinaryArray::<512>::NULL;
    row.get_data(col_index, &mut buf)?;
    while !buf.is_complete() {
        // Process bytes in stream without allocation. We can assume repeated calls to
        // get_data do not return `None` since it would have done so on the first call.
        process_slice(buf.as_bytes().unwrap());
    }
    Ok(())
}

fn process_slice(text: &[u8]) { /*...*/}

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pub fn indicator(&self) -> Indicator

Read access to the underlying ODBC indicator. After data has been fetched the indicator value is set to the length the buffer should have had to hold the entire value. It may also be Indicator::Null to indicate NULL or Indicator::NoTotal which tells us the data source does not know how big the buffer must be to hold the complete value. Indicator::NoTotal implies that the content of the current buffer is valid up to its maximum capacity.

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impl VarBinary where
B: Borrow<[u8 ]>,

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pub fn hide_truncation(&mut self)

Call this method to reset the indicator to a value which matches the length returned by the Self::as_bytes method. This is useful if you want to insert values into the database despite the fact, that they might have been truncated.

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impl<'a> VarBinary<&'a [u8 ]>

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pub const NULL: Self

Indicates missing data

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pub fn new(value: &'a [u8 ]) -> Self

Constructs a new instance containing the bytes in the specified buffer.

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impl<const LENGTH: usize> VarBinary<[u8 ; LENGTH]>

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pub const NULL: Self

Indicates a missing value.

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pub fn new(bytes: &[u8 ]) -> Self

Construct from a slice. If value is longer than LENGTH it will be truncated.

Trait Implementations

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impl CData for VarBinary where
B: Borrow<[u8 ]>,

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fn cdata_type(&self) -> CDataType

The identifier of the C data type of the value buffer. When it is retrieving data from the data source with fetch, the driver converts the data to this type. When it sends data to the source, the driver converts the data from this type. Read more

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fn indicator_ptr(&self) -> *const isize

Indicates the length of variable sized types. May be zero for fixed sized types. Used to determine the size or existence of input parameters. Read more

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fn value_ptr(&self) -> *const c_void

Pointer to a value corresponding to the one described by cdata_type.

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fn buffer_length(&self) -> isize

Maximum length of the type in bytes (not characters). It is required to index values in bound buffers, if more than one parameter is bound. Can be set to zero for types not bound as parameter arrays, i.e. CStr. Read more

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