json request example

guide/src/qs_7.md

@@ -55,7 +55,46 @@ fn index(req: HttpRequest) -> HttpResponse {
 }
 # fn main() {}
 ```
- 
+
+
+## JSON Request
+
+Unfortunately, because of async nature of actix web framework, deserializing json
+requests is not very ergonomic process. First you need to load whole body into
+temporal storage and only then you can deserialize it.
+
+Here is simple example. We will deserialize *MyObj* struct.
+
+```rust,ignore
+#[derive(Debug, Deserialize)]
+struct MyObj {
+    name: String,
+    number: i32,
+}
+```
+
+We need to load request body first.
+
+```rust,ignore
+fn index(mut req: HttpRequest) -> Future<Item=HttpResponse, Error=Error> {
+
+   req.payload_mut().readany()
+     .fold(BytesMut::new(), |mut body, chunk| {   // <- load request body
+         body.extend(chunk);
+         result::<_, error::PayloadError>(Ok(body))
+     })
+    .and_then(|body| {  // <- body is loaded, now we can deserialize json
+        let obj = serde_json::from_slice::<MyObj>(&body).unwrap();
+        println!("MODEL: {:?}", obj);    // <- do something with payload
+        ok(httpcodes::HTTPOk.response()) // <- send response
+    })
+}
+```
+
+Full example is available in 
+[examples directory](https://github.com/actix/actix-web/tree/master/examples/json/).
+
+
 ## JSON Response
 
 The `Json` type allows you to respond with well-formed JSON data: simply return a value of