Make Response::into_json deserialize into a serde DeserializeOwned

This removes the necessity to take the result of Response::into_json and
having to convert it into a struct by using serde_json::from_value

This adds no new dependencies since serde_json already depends on serde.
Users of ureq will have to include `serde_derive` either by importing it
directly or by using serde with the `derive` feature, unless they want to
manually implement `Deserialize` on their structs.

Cargo.toml

@@ -15,7 +15,7 @@ all-features = true
 
 [features]
 default = ["tls", "cookies"]
-json = ["serde_json"]
+json = ["serde", "serde_json"]
 charset = ["encoding"]
 tls = ["rustls", "webpki", "webpki-roots"]
 native-certs = ["rustls-native-certs"]
@@ -34,5 +34,9 @@ rustls = { version = "0.17", optional = true, features = [] }
 webpki = { version = "0.21", optional = true }
 webpki-roots = { version = "0.19", optional = true }
 rustls-native-certs = { version = "0.3", optional = true }
+serde = { version = "1", optional = true }
 serde_json = { version = "1", optional = true }
 encoding = { version = "0.2", optional = true }
+
+[dev-dependencies]
+serde = { version = "1", features = ["derive"] }

src/body.rs

@@ -10,8 +10,6 @@ use encoding::EncoderTrap;
 
 #[cfg(feature = "json")]
 use super::SerdeValue;
-#[cfg(feature = "json")]
-use serde_json;
 
 /// The different kinds of bodies to send.
 ///

src/response.rs

@@ -10,7 +10,7 @@ use crate::stream::Stream;
 use crate::unit::Unit;
 
 #[cfg(feature = "json")]
-use serde_json;
+use serde::de::DeserializeOwned;
 
 #[cfg(feature = "charset")]
 use encoding::label::encoding_from_whatwg_label;
@@ -382,16 +382,23 @@ impl Response {
     /// Example:
     ///
     /// ```
+    /// # use serde::Deserialize;
+    ///
+    /// #[derive(Deserialize)]
+    /// struct Hello {
+    ///     hello: String,
+    /// }
+    ///
     /// let resp =
     ///     ureq::get("https://ureq.s3.eu-central-1.amazonaws.com/hello_world.json")
     ///         .call();
     ///
-    /// let json = resp.into_json().unwrap();
+    /// let json = resp.into_json::<Hello>().unwrap();
     ///
-    /// assert_eq!(json["hello"], "world");
+    /// assert_eq!(json.hello, "world");
     /// ```
     #[cfg(feature = "json")]
-    pub fn into_json(self) -> IoResult<serde_json::Value> {
+    pub fn into_json<T: DeserializeOwned>(self) -> IoResult<T> {
         let reader = self.into_reader();
         serde_json::from_reader(reader).map_err(|e| {
             IoError::new(
@@ -723,15 +730,19 @@ mod tests {
     #[test]
     #[cfg(feature = "json")]
     fn parse_simple_json() {
+        use serde::Deserialize;
+
+        #[derive(Deserialize)]
+        struct Hello {
+            hello: String,
+        }
+
         let s = "HTTP/1.1 200 OK\r\n\
              \r\n\
              {\"hello\":\"world\"}";
         let resp = s.parse::<Response>().unwrap();
-        let v = resp.into_json().unwrap();
-        let compare = "{\"hello\":\"world\"}"
-            .parse::<serde_json::Value>()
-            .unwrap();
-        assert_eq!(v, compare);
+        let v = resp.into_json::<Hello>().unwrap();
+        assert_eq!(v.hello, "world");
     }
 
     #[test]

src/test/simple.rs

@@ -61,6 +61,13 @@ fn body_as_text() {
 #[test]
 #[cfg(feature = "json")]
 fn body_as_json() {
+    use serde::Deserialize;
+
+    #[derive(Deserialize)]
+    struct Hello {
+        hello: String,
+    }
+
     test::set_handler("/body_as_json", |_unit| {
         test::make_response(
             200,
@@ -70,8 +77,8 @@ fn body_as_json() {
         )
     });
     let resp = get("test://host/body_as_json").call();
-    let json = resp.into_json().unwrap();
-    assert_eq!(json["hello"], "world");
+    let json = resp.into_json::<Hello>().unwrap();
+    assert_eq!(json.hello, "world");
 }
 
 #[test]

tests/https-agent.rs

@@ -17,6 +17,14 @@ fn tls_connection_close() {
 #[cfg(feature = "json")]
 #[test]
 fn agent_set_cookie() {
+    use serde::Deserialize;
+    use std::collections::HashMap;
+
+    #[derive(Deserialize)]
+    struct HttpBin {
+        headers: HashMap<String, String>,
+    }
+
     let agent = ureq::Agent::default().build();
     let cookie = ureq::Cookie::build("name", "value")
         .domain("httpbin.org")
@@ -30,10 +38,9 @@ fn agent_set_cookie() {
     assert_eq!(resp.status(), 200);
     assert_eq!(
         "name=value",
-        resp.into_json()
-            .unwrap()
-            .get("headers")
+        resp.into_json::<HttpBin>()
             .unwrap()
+            .headers
             .get("Cookie")
             .unwrap()
     );