--- title: Requests --- import CodeBlock from "@site/src/components/code_block"; # JSON Request There are several options for json body deserialization. The first option is to use _Json_ extractor. First, you define a handler function that accepts `Json<T>` as a parameter, then, you use the `.to()` method for registering this handler. It is also possible to accept arbitrary valid json object by using `serde_json::Value` as a type `T`. First example of `JSON Request` depends on `serde`: ```toml [dependencies] serde = { version = "1.0", features = ["derive"] } ``` Second example of `JSON Request` depends on `serde` and `serde_json` and `futures`: ```toml [dependencies] serde = { version = "1.0", features = ["derive"] } serde_json = "1" futures = "0.3" ``` If you want to add default value for a field, refer to `serde`'s [documentation](https://serde.rs/attr-default.html). <CodeBlock example="requests" file="main.rs" section="json-request" /> You may also manually load the payload into memory and then deserialize it. In the following example, we will deserialize a _MyObj_ struct. We need to load the request body first and then deserialize the json into an object. <CodeBlock example="requests" file="manual.rs" section="json-manual" /> > A complete example for both options is available in [examples directory][examples]. ## Content Encoding Actix Web automatically _decompresses_ payloads. The following codecs are supported: - Brotli - Gzip - Deflate - Zstd If request headers contain a `Content-Encoding` header, the request payload is decompressed according to the header value. Multiple codecs are not supported, i.e: `Content-Encoding: br, gzip`. ## Chunked transfer encoding Actix automatically decodes _chunked_ encoding. The [`web::Payload`][payloadextractor] extractor already contains the decoded byte stream. If the request payload is compressed with one of the supported compression codecs (br, gzip, deflate), then the byte stream is decompressed. ## Multipart body Actix Web provides multipart stream support with an external crate, [`actix-multipart`][multipartcrate]. > A full example is available in the [examples directory][multipartexample]. ## Urlencoded body Actix Web provides support for _application/x-www-form-urlencoded_ encoded bodies with the [`web::Form`][formencoded] extractor which resolves to the deserialized instance. The type of the instance must implement the `Deserialize` trait from _serde_. The _UrlEncoded_ future can resolve into an error in several cases: - content type is not `application/x-www-form-urlencoded` - transfer encoding is `chunked`. - content-length is greater than 256k - payload terminates with error. <CodeBlock example="requests" file="urlencoded.rs" section="urlencoded" /> ## Streaming request _HttpRequest_ is a stream of `Bytes` objects. It can be used to read the request body payload. In the following example, we read and print the request payload chunk by chunk: <CodeBlock example="requests" file="streaming.rs" section="streaming" /> [examples]: https://github.com/actix/examples/tree/master/json/json [multipartstruct]: https://docs.rs/actix-multipart/0.2/actix_multipart/struct.Multipart.html [fieldstruct]: https://docs.rs/actix-multipart/0.2/actix_multipart/struct.Field.html [multipartexample]: https://github.com/actix/examples/tree/master/forms/multipart [urlencoded]: https://docs.rs/actix-web/4/actix_web/dev/struct.UrlEncoded.html [payloadextractor]: https://docs.rs/actix-web/4/actix_web/web/struct.Payload.html [multipartcrate]: https://crates.io/crates/actix-multipart [formencoded]: https://docs.rs/actix-web/4/actix_web/web/struct.Form.html