1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136

use axum::{
    async_trait,
    body::HttpBody,
    extract::{
        rejection::{FailedToDeserializeQueryString, FormRejection, InvalidFormContentType},
        FromRequest, RequestParts,
    },
    BoxError,
};
use bytes::Bytes;
use http::{header, Method};
use serde::de::DeserializeOwned;
use std::ops::Deref;

/// Extractor that deserializes `application/x-www-form-urlencoded` requests
/// into some type.
///
/// `T` is expected to implement [`serde::Deserialize`].
///
/// # Differences from `axum::extract::Form`
///
/// This extractor uses [`serde_html_form`] under-the-hood which supports multi-value items. These
/// are sent by multiple `<input>` attributes of the same name (e.g. checkboxes) and `<select>`s
/// with the `multiple` attribute. Those values can be collected into a `Vec` or other sequential
/// container.
///
/// # Example
///
/// ```rust,no_run
/// use axum_extra::extract::Form;
/// use serde::Deserialize;
///
/// #[derive(Deserialize)]
/// struct Payload {
///     #[serde(rename = "value")]
///     values: Vec<String>,
/// }
///
/// async fn accept_form(Form(payload): Form<Payload>) {
///     // ...
/// }
/// ```
///
/// [`serde_html_form`]: https://crates.io/crates/serde_html_form
#[derive(Debug, Clone, Copy, Default)]
pub struct Form<T>(pub T);

impl<T> Deref for Form<T> {
    type Target = T;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

#[async_trait]
impl<T, B> FromRequest<B> for Form<T>
where
    T: DeserializeOwned,
    B: HttpBody + Send,
    B::Data: Send,
    B::Error: Into<BoxError>,
{
    type Rejection = FormRejection;

    async fn from_request(req: &mut RequestParts<B>) -> Result<Self, Self::Rejection> {
        if req.method() == Method::GET {
            let query = req.uri().query().unwrap_or_default();
            let value = serde_html_form::from_str(query)
                .map_err(FailedToDeserializeQueryString::__private_new::<(), _>)?;
            Ok(Form(value))
        } else {
            if !has_content_type(req, &mime::APPLICATION_WWW_FORM_URLENCODED) {
                return Err(InvalidFormContentType::default().into());
            }

            let bytes = Bytes::from_request(req).await?;
            let value = serde_html_form::from_bytes(&bytes)
                .map_err(FailedToDeserializeQueryString::__private_new::<(), _>)?;

            Ok(Form(value))
        }
    }
}

// this is duplicated in `axum/src/extract/mod.rs`
fn has_content_type<B>(req: &RequestParts<B>, expected_content_type: &mime::Mime) -> bool {
    let content_type = if let Some(content_type) = req.headers().get(header::CONTENT_TYPE) {
        content_type
    } else {
        return false;
    };

    let content_type = if let Ok(content_type) = content_type.to_str() {
        content_type
    } else {
        return false;
    };

    content_type.starts_with(expected_content_type.as_ref())
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::test_helpers::*;
    use axum::{routing::post, Router};
    use http::{header::CONTENT_TYPE, StatusCode};
    use serde::Deserialize;

    #[tokio::test]
    async fn supports_multiple_values() {
        #[derive(Deserialize)]
        struct Data {
            #[serde(rename = "value")]
            values: Vec<String>,
        }

        let app = Router::new().route(
            "/",
            post(|Form(data): Form<Data>| async move { data.values.join(",") }),
        );

        let client = TestClient::new(app);

        let res = client
            .post("/")
            .header(CONTENT_TYPE, "application/x-www-form-urlencoded")
            .body("value=one&value=two")
            .send()
            .await;

        assert_eq!(res.status(), StatusCode::OK);
        assert_eq!(res.text().await, "one,two");
    }
}