Function arrow_json::reader::infer_json_schema_from_seekable
source · pub fn infer_json_schema_from_seekable<R: BufRead + Seek>(
reader: R,
max_read_records: Option<usize>,
) -> Result<(Schema, usize), ArrowError>
Expand description
Infer the fields of a JSON file by reading the first n records of the file, with
max_read_records
controlling the maximum number of records to read.
If max_read_records
is not set, the whole file is read to infer its field types.
Returns inferred schema and number of records read.
Contrary to infer_json_schema
, this function will seek back to the start of the reader
.
That way, the reader
can be used immediately afterwards to create a Reader
.
§Examples
use std::fs::File;
use std::io::BufReader;
use arrow_json::reader::infer_json_schema_from_seekable;
let file = File::open("test/data/mixed_arrays.json").unwrap();
// file's cursor's offset at 0
let mut reader = BufReader::new(file);
let inferred_schema = infer_json_schema_from_seekable(&mut reader, None).unwrap();
// file's cursor's offset automatically set at 0