async_graphql/resolver_utils/
scalar.rs

1use crate::{InputValueResult, Value};
2
3/// A GraphQL scalar.
4///
5/// You can implement the trait to create a custom scalar.
6///
7/// # Examples
8///
9/// ```rust
10/// use async_graphql::*;
11///
12/// struct MyInt(i32);
13///
14/// #[Scalar]
15/// impl ScalarType for MyInt {
16///     fn parse(value: Value) -> InputValueResult<Self> {
17///         if let Value::Number(n) = &value {
18///             if let Some(n) = n.as_i64() {
19///                 return Ok(MyInt(n as i32));
20///             }
21///         }
22///         Err(InputValueError::expected_type(value))
23///     }
24///
25///     fn to_value(&self) -> Value {
26///         Value::Number(self.0.into())
27///     }
28/// }
29/// ```
30pub trait ScalarType: Sized + Send {
31    /// Parse a scalar value.
32    fn parse(value: Value) -> InputValueResult<Self>;
33
34    /// Checks for a valid scalar value.
35    ///
36    /// Implementing this function can find incorrect input values during the
37    /// verification phase, which can improve performance.
38    fn is_valid(_value: &Value) -> bool {
39        true
40    }
41
42    /// Convert the scalar to `Value`.
43    fn to_value(&self) -> Value;
44}
45
46/// Define a scalar
47///
48/// If your type implemented `serde::Serialize` and `serde::Deserialize`, then
49/// you can use this macro to define a scalar more simply. It helps you
50/// implement the `ScalarType::parse` and `ScalarType::to_value` functions by
51/// calling the [from_value](fn.from_value.html) and
52/// [to_value](fn.to_value.html) functions.
53///
54/// # Examples
55///
56/// ```rust
57/// use async_graphql::*;
58/// use serde::{Serialize, Deserialize};
59/// use std::collections::HashMap;
60///
61/// #[derive(Serialize, Deserialize)]
62/// struct MyValue {
63///     a: i32,
64///     b: HashMap<String, i32>,
65/// }
66///
67/// scalar!(MyValue);
68///
69/// // Rename to `MV`.
70/// // scalar!(MyValue, "MV");
71///
72/// // Rename to `MV` and add description.
73/// // scalar!(MyValue, "MV", "This is my value");
74///
75/// // Rename to `MV`, add description and specifiedByURL.
76/// // scalar!(MyValue, "MV", "This is my value", "https://tools.ietf.org/html/rfc4122");
77///
78/// struct Query;
79///
80/// #[Object]
81/// impl Query {
82///     async fn value(&self, input: MyValue) -> MyValue {
83///         input
84///     }
85/// }
86///
87/// # tokio::runtime::Runtime::new().unwrap().block_on(async move {
88/// let schema = Schema::new(Query, EmptyMutation, EmptySubscription);
89/// let res = schema.execute(r#"{ value(input: {a: 10, b: {v1: 1, v2: 2} }) }"#).await.into_result().unwrap().data;
90/// assert_eq!(res, value!({
91///     "value": {
92///         "a": 10,
93///         "b": {"v1": 1, "v2": 2},
94///     }
95/// }));
96/// # });
97/// ```
98#[macro_export]
99macro_rules! scalar {
100    ($ty:ty, $name:literal, $desc:literal, $specified_by_url:literal) => {
101        $crate::scalar_internal!(
102            $ty,
103            $name,
104            ::std::option::Option::Some(::std::string::ToString::to_string($desc)),
105            ::std::option::Option::Some(::std::string::ToString::to_string($specified_by_url))
106        );
107    };
108
109    ($ty:ty, $name:literal, $desc:literal) => {
110        $crate::scalar_internal!(
111            $ty,
112            $name,
113            ::std::option::Option::Some(::std::string::ToString::to_string($desc)),
114            ::std::option::Option::None
115        );
116    };
117
118    ($ty:ty, $name:literal) => {
119        $crate::scalar_internal!(
120            $ty,
121            $name,
122            ::std::option::Option::None,
123            ::std::option::Option::None
124        );
125    };
126
127    ($ty:ty) => {
128        $crate::scalar_internal!(
129            $ty,
130            ::std::stringify!($ty),
131            ::std::option::Option::None,
132            ::std::option::Option::None
133        );
134    };
135}
136
137#[macro_export]
138#[doc(hidden)]
139macro_rules! scalar_internal {
140    ($ty:ty, $name:expr, $desc:expr, $specified_by_url:expr) => {
141        impl $crate::ScalarType for $ty {
142            fn parse(value: $crate::Value) -> $crate::InputValueResult<Self> {
143                ::std::result::Result::Ok($crate::from_value(value)?)
144            }
145
146            fn to_value(&self) -> $crate::Value {
147                $crate::to_value(self).unwrap_or_else(|_| $crate::Value::Null)
148            }
149        }
150
151        impl $crate::InputType for $ty {
152            type RawValueType = Self;
153
154            fn type_name() -> ::std::borrow::Cow<'static, ::std::primitive::str> {
155                ::std::borrow::Cow::Borrowed($name)
156            }
157
158            fn create_type_info(
159                registry: &mut $crate::registry::Registry,
160            ) -> ::std::string::String {
161                registry.create_input_type::<$ty, _>($crate::registry::MetaTypeId::Scalar, |_| {
162                    $crate::registry::MetaType::Scalar {
163                        name: ::std::borrow::ToOwned::to_owned($name),
164                        description: $desc,
165                        is_valid: ::std::option::Option::Some(::std::sync::Arc::new(|value| {
166                            <$ty as $crate::ScalarType>::is_valid(value)
167                        })),
168                        visible: ::std::option::Option::None,
169                        inaccessible: false,
170                        tags: ::std::default::Default::default(),
171                        specified_by_url: $specified_by_url,
172                        directive_invocations: ::std::vec::Vec::new(),
173                    }
174                })
175            }
176
177            fn parse(
178                value: ::std::option::Option<$crate::Value>,
179            ) -> $crate::InputValueResult<Self> {
180                <$ty as $crate::ScalarType>::parse(value.unwrap_or_default())
181            }
182
183            fn to_value(&self) -> $crate::Value {
184                <$ty as $crate::ScalarType>::to_value(self)
185            }
186
187            fn as_raw_value(&self) -> ::std::option::Option<&Self::RawValueType> {
188                ::std::option::Option::Some(self)
189            }
190        }
191
192        $crate::scalar_internal_output!($ty, $name, $desc, $specified_by_url);
193    };
194}
195
196#[cfg(feature = "boxed-trait")]
197#[macro_export]
198#[doc(hidden)]
199macro_rules! scalar_internal_output {
200    ($ty:ty, $name:expr, $desc:expr, $specified_by_url:expr) => {
201        #[$crate::async_trait::async_trait]
202        impl $crate::OutputType for $ty {
203            fn type_name() -> ::std::borrow::Cow<'static, ::std::primitive::str> {
204                ::std::borrow::Cow::Borrowed($name)
205            }
206
207            fn create_type_info(
208                registry: &mut $crate::registry::Registry,
209            ) -> ::std::string::String {
210                registry.create_output_type::<$ty, _>($crate::registry::MetaTypeId::Scalar, |_| {
211                    $crate::registry::MetaType::Scalar {
212                        name: ::std::borrow::ToOwned::to_owned($name),
213                        description: $desc,
214                        is_valid: ::std::option::Option::Some(::std::sync::Arc::new(|value| {
215                            <$ty as $crate::ScalarType>::is_valid(value)
216                        })),
217                        visible: ::std::option::Option::None,
218                        inaccessible: false,
219                        tags: ::std::default::Default::default(),
220                        specified_by_url: $specified_by_url,
221                        directive_invocations: ::std::vec::Vec::new(),
222                    }
223                })
224            }
225
226            async fn resolve(
227                &self,
228                _: &$crate::ContextSelectionSet<'_>,
229                _field: &$crate::Positioned<$crate::parser::types::Field>,
230            ) -> $crate::ServerResult<$crate::Value> {
231                ::std::result::Result::Ok($crate::ScalarType::to_value(self))
232            }
233        }
234    };
235}
236
237#[cfg(not(feature = "boxed-trait"))]
238#[macro_export]
239#[doc(hidden)]
240macro_rules! scalar_internal_output {
241    ($ty:ty, $name:expr, $desc:expr, $specified_by_url:expr) => {
242        impl $crate::OutputType for $ty {
243            fn type_name() -> ::std::borrow::Cow<'static, ::std::primitive::str> {
244                ::std::borrow::Cow::Borrowed($name)
245            }
246
247            fn create_type_info(
248                registry: &mut $crate::registry::Registry,
249            ) -> ::std::string::String {
250                registry.create_output_type::<$ty, _>($crate::registry::MetaTypeId::Scalar, |_| {
251                    $crate::registry::MetaType::Scalar {
252                        name: ::std::borrow::ToOwned::to_owned($name),
253                        description: $desc,
254                        is_valid: ::std::option::Option::Some(::std::sync::Arc::new(|value| {
255                            <$ty as $crate::ScalarType>::is_valid(value)
256                        })),
257                        visible: ::std::option::Option::None,
258                        inaccessible: false,
259                        tags: ::std::default::Default::default(),
260                        specified_by_url: $specified_by_url,
261                        directive_invocations: ::std::vec::Vec::new(),
262                    }
263                })
264            }
265
266            async fn resolve(
267                &self,
268                _: &$crate::ContextSelectionSet<'_>,
269                _field: &$crate::Positioned<$crate::parser::types::Field>,
270            ) -> $crate::ServerResult<$crate::Value> {
271                ::std::result::Result::Ok($crate::ScalarType::to_value(self))
272            }
273        }
274    };
275}
async_graphql/resolver_utils/scalar.rs

async_graphql/resolver_utils/
scalar.rs
