Function arrow::json::reader::infer_json_schema_from_seekable

pub fn infer_json_schema_from_seekable<R: Read + Seek>(
    reader: &mut BufReader<R>, 
    max_read_records: Option<usize>
) -> Result<SchemaRef>

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.

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