# JSON read
When compiled with feature `io_json`, you can use this crate to read NDJSON files:
```rust
{{#include ../../../examples/ndjson_read.rs}}
```
Note how deserialization can be performed on a separate thread pool to avoid
blocking the runtime (see also [here](https://ryhl.io/blog/async-what-is-blocking/)).
This crate also supports reading JSON, at the expense of being unable to read the file in chunks.
```rust
{{#include ../../../examples/json_read.rs}}
```
## Metadata and inference
This crate uses the following mapping between Arrow's data type and JSON:
| Bool | Boolean |
| Int | Int64 |
| Float | Float64 |
| String | Utf8 |
| List | List |
| Object | Struct |