fastavro.read

class reader(fo: Union[IO, fastavro.io.json_decoder.AvroJSONDecoder], reader_schema: Union[str, List[T], Dict[KT, VT], None] = None, return_record_name: bool = False)

Iterator over records in an avro file.

Parameters:
  • fo – File-like object to read from
  • reader_schema – Reader schema
  • return_record_name – If true, when reading a union of records, the result will be a tuple where the first value is the name of the record and the second value is the record itself

Example:

from fastavro import reader
with open('some-file.avro', 'rb') as fo:
    avro_reader = reader(fo)
    for record in avro_reader:
        process_record(record)

The fo argument is a file-like object so another common example usage would use an io.BytesIO object like so:

from io import BytesIO
from fastavro import writer, reader

fo = BytesIO()
writer(fo, schema, records)
fo.seek(0)
for record in reader(fo):
    process_record(record)
metadata

Key-value pairs in the header metadata

codec

The codec used when writing

writer_schema

The schema used when writing

reader_schema

The schema used when reading (if provided)

class block_reader(fo: IO, reader_schema: Union[str, List[T], Dict[KT, VT], None] = None, return_record_name: bool = False)

Iterator over Block in an avro file.

Parameters:
  • fo – Input stream
  • reader_schema – Reader schema
  • return_record_name – If true, when reading a union of records, the result will be a tuple where the first value is the name of the record and the second value is the record itself

Example:

from fastavro import block_reader
with open('some-file.avro', 'rb') as fo:
    avro_reader = block_reader(fo)
    for block in avro_reader:
        process_block(block)
metadata

Key-value pairs in the header metadata

codec

The codec used when writing

writer_schema

The schema used when writing

reader_schema

The schema used when reading (if provided)

class Block(bytes_, num_records, codec, reader_schema, writer_schema, named_schemas, offset, size, return_record_name=False)

An avro block. Will yield records when iterated over

num_records

Number of records in the block

writer_schema

The schema used when writing

reader_schema

The schema used when reading (if provided)

offset

Offset of the block from the beginning of the avro file

size

Size of the block in bytes

schemaless_reader(fo: IO, writer_schema: Union[str, List[T], Dict[KT, VT]], reader_schema: Union[str, List[T], Dict[KT, VT], None] = None, return_record_name: bool = False) → Union[None, str, float, int, decimal.Decimal, bool, bytes, List[T], Dict[KT, VT]]

Reads a single record written using the schemaless_writer()

Parameters:
  • fo – Input stream
  • writer_schema – Schema used when calling schemaless_writer
  • reader_schema – If the schema has changed since being written then the new schema can be given to allow for schema migration
  • return_record_name – If true, when reading a union of records, the result will be a tuple where the first value is the name of the record and the second value is the record itself

Example:

parsed_schema = fastavro.parse_schema(schema)
with open('file', 'rb') as fp:
    record = fastavro.schemaless_reader(fp, parsed_schema)

Note: The schemaless_reader can only read a single record.

is_avro(path_or_buffer: Union[str, IO]) → bool

Return True if path (or buffer) points to an Avro file. This will only work for avro files that contain the normal avro schema header like those create from writer(). This function is not intended to be used with binary data created from schemaless_writer() since that does not include the avro header.

Parameters:path_or_buffer – Path to file