Struct Writer

pub struct Writer<'a, W: Write> { /* private fields */ }

Main interface for writing Avro formatted values.

It is critical to call flush before Writer<W> is dropped. Though dropping will attempt to flush the contents of the buffer, any errors that happen in the process of dropping will be ignored. Calling flush ensures that the buffer is empty and thus dropping will not even attempt file operations.

Implementations

impl<'a, W: Write> Writer<'a, W>

pub fn builder() -> WriterBuilder<'a, W>

Create an instance of Writer using the builder syntax

impl<'a, W: Write> Writer<'a, W>

pub fn new(schema: &'a Schema, writer: W) -> Self

Creates a Writer given a Schema and something implementing the io::Write trait to write to. No compression Codec will be used.

pub fn with_codec(schema: &'a Schema, writer: W, codec: Codec) -> Self

Creates a Writer with a specific Codec given a Schema and something implementing the io::Write trait to write to.

pub fn with_schemata( schema: &'a Schema, schemata: Vec<&'a Schema>, writer: W, codec: Codec, ) -> Self

Creates a Writer with a specific Codec given a Schema and something implementing the io::Write trait to write to. If the schema is incomplete, i.e. contains Schema::Refs then all dependencies must be provided in schemata.

pub fn append_to(schema: &'a Schema, writer: W, marker: [u8; 16]) -> Self

Creates a Writer that will append values to already populated std::io::Write using the provided marker No compression Codec will be used.

pub fn append_to_with_codec( schema: &'a Schema, writer: W, codec: Codec, marker: [u8; 16], ) -> Self

Creates a Writer that will append values to already populated std::io::Write using the provided marker

pub fn append_to_with_codec_schemata( schema: &'a Schema, schemata: Vec<&'a Schema>, writer: W, codec: Codec, marker: [u8; 16], ) -> Self

Creates a Writer that will append values to already populated std::io::Write using the provided marker

pub fn schema(&self) -> &'a Schema

Get a reference to the Schema associated to a Writer.

pub fn append<T: Into<Value>>(&mut self, value: T) -> AvroResult<usize>

Append a compatible value (implementing the ToAvro trait) to a Writer, also performing schema validation.

Returns the number of bytes written (it might be 0, see below).

NOTE: This function is not guaranteed to perform any actual write, since it relies on internal buffering for performance reasons. If you want to be sure the value has been written, then call flush.

pub fn append_value_ref(&mut self, value: &Value) -> AvroResult<usize>

Append a compatible value to a Writer, also performing schema validation.

Returns the number of bytes written (it might be 0, see below).

NOTE: This function is not guaranteed to perform any actual write, since it relies on internal buffering for performance reasons. If you want to be sure the value has been written, then call flush.

pub fn append_ser<S: Serialize>(&mut self, value: S) -> AvroResult<usize>

Append anything implementing the Serialize trait to a Writer for serde compatibility, also performing schema validation.

Returns the number of bytes written.

NOTE: This function is not guaranteed to perform any actual write, since it relies on internal buffering for performance reasons. If you want to be sure the value has been written, then call flush.

pub fn extend<I, T: Into<Value>>(&mut self, values: I) -> AvroResult<usize>

where I: IntoIterator<Item = T>,

Extend a Writer with an Iterator of compatible values (implementing the ToAvro trait), also performing schema validation.

Returns the number of bytes written.

NOTE: This function forces the written data to be flushed (an implicit call to flush is performed).

pub fn extend_ser<I, T: Serialize>(&mut self, values: I) -> AvroResult<usize>

where I: IntoIterator<Item = T>,

Extend a Writer with an Iterator of anything implementing the Serialize trait for serde compatibility, also performing schema validation.

Returns the number of bytes written.

NOTE: This function forces the written data to be flushed (an implicit call to flush is performed).

pub fn extend_from_slice(&mut self, values: &[Value]) -> AvroResult<usize>

Extend a Writer by appending each Value from a slice, while also performing schema validation on each value appended.

Returns the number of bytes written.

NOTE: This function forces the written data to be flushed (an implicit call to flush is performed).

pub fn flush(&mut self) -> AvroResult<usize>

Flush the content to the inner Writer.

Call this function to make sure all the content has been written before releasing the Writer. This will also write the header if it wasn’t written yet and hasn’t been disabled using WriterBuilder::has_header.

Returns the number of bytes written.

pub fn into_inner(self) -> AvroResult<W>

Return what the Writer is writing to, consuming the Writer itself.

NOTE: This function forces the written data to be flushed (an implicit call to flush is performed).

pub fn get_ref(&self) -> &W

Gets a reference to the underlying writer.

NOTE: There is likely data still in the buffer. To have all the data in the writer call flush first.

pub fn get_mut(&mut self) -> &mut W

Gets a mutable reference to the underlying writer.

It is inadvisable to directly write to the underlying writer.

NOTE: There is likely data still in the buffer. To have all the data in the writer call flush first.

pub fn add_user_metadata<T: AsRef<[u8]>>( &mut self, key: String, value: T, ) -> AvroResult<()>

Adds custom metadata to the file. This method could be used only before adding the first record to the writer.

Trait Implementations

impl<W: Write> Drop for Writer<'_, W>

fn drop(&mut self)

Drop the writer, will try to flush ignoring any errors.