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
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
#![forbid(unsafe_code)]
/*!
Generate JSON Schema documents from Rust code

## Basic Usage

If you don't really care about the specifics, the easiest way to generate a JSON schema for your types is to `#[derive(JsonSchema)]` and use the `schema_for!` macro. All fields of the type must also implement `JsonSchema` - Schemars implements this for many standard library types.

```rust
use schemars::{schema_for, JsonSchema};

#[derive(JsonSchema)]
pub struct MyStruct {
    pub my_int: i32,
    pub my_bool: bool,
    pub my_nullable_enum: Option<MyEnum>,
}

#[derive(JsonSchema)]
pub enum MyEnum {
    StringNewType(String),
    StructVariant { floats: Vec<f32> },
}

let schema = schema_for!(MyStruct);
println!("{}", serde_json::to_string_pretty(&schema).unwrap());
```

<details>
<summary>Click to see the output JSON schema...</summary>

```json
{
    "$schema": "http://json-schema.org/draft-07/schema#",
    "title": "MyStruct",
    "type": "object",
    "required": [
        "my_bool",
        "my_int"
    ],
    "properties": {
        "my_bool": {
            "type": "boolean"
        },
        "my_int": {
            "type": "integer",
            "format": "int32"
        },
        "my_nullable_enum": {
            "anyOf": [
                {
                    "$ref": "#/definitions/MyEnum"
                },
                {
                    "type": "null"
                }
            ]
        }
    },
    "definitions": {
        "MyEnum": {
            "anyOf": [
                {
                    "type": "object",
                    "required": [
                        "StringNewType"
                    ],
                    "properties": {
                        "StringNewType": {
                            "type": "string"
                        }
                    },
                    "additionalProperties": false
                },
                {
                    "type": "object",
                    "required": [
                        "StructVariant"
                    ],
                    "properties": {
                        "StructVariant": {
                            "type": "object",
                            "required": [
                                "floats"
                            ],
                            "properties": {
                                "floats": {
                                    "type": "array",
                                    "items": {
                                        "type": "number",
                                        "format": "float"
                                    }
                                }
                            }
                        }
                    },
                    "additionalProperties": false
                }
            ]
        }
    }
}
```
</details>

### Serde Compatibility

One of the main aims of this library is compatibility with [Serde](https://github.com/serde-rs/serde). Any generated schema *should* match how [serde_json](https://github.com/serde-rs/json) would serialize/deserialize to/from JSON. To support this, Schemars will check for any `#[serde(...)]` attributes on types that derive `JsonSchema`, and adjust the generated schema accordingly.

```rust
use schemars::{schema_for, JsonSchema};
use serde::{Deserialize, Serialize};

#[derive(Deserialize, Serialize, JsonSchema)]
#[serde(rename_all = "camelCase", deny_unknown_fields)]
pub struct MyStruct {
    #[serde(rename = "myNumber")]
    pub my_int: i32,
    pub my_bool: bool,
    #[serde(default)]
    pub my_nullable_enum: Option<MyEnum>,
}

#[derive(Deserialize, Serialize, JsonSchema)]
#[serde(untagged)]
pub enum MyEnum {
    StringNewType(String),
    StructVariant { floats: Vec<f32> },
}

let schema = schema_for!(MyStruct);
println!("{}", serde_json::to_string_pretty(&schema).unwrap());
```

<details>
<summary>Click to see the output JSON schema...</summary>

```json
{
    "$schema": "http://json-schema.org/draft-07/schema#",
    "title": "MyStruct",
    "type": "object",
    "required": [
        "myBool",
        "myNumber"
    ],
    "properties": {
        "myBool": {
            "type": "boolean"
        },
        "myNullableEnum": {
            "default": null,
            "anyOf": [
                {
                    "$ref": "#/definitions/MyEnum"
                },
                {
                    "type": "null"
                }
            ]
        },
        "myNumber": {
            "type": "integer",
            "format": "int32"
        }
    },
    "additionalProperties": false,
    "definitions": {
        "MyEnum": {
            "anyOf": [
                {
                    "type": "string"
                },
                {
                    "type": "object",
                    "required": [
                        "floats"
                    ],
                    "properties": {
                        "floats": {
                            "type": "array",
                            "items": {
                                "type": "number",
                                "format": "float"
                            }
                        }
                    }
                }
            ]
        }
    }
}
```
</details>

`#[serde(...)]` attributes can be overriden using `#[schemars(...)]` attributes, which behave identically (e.g. `#[schemars(rename_all = "camelCase")]`). You may find this useful if you want to change the generated schema without affecting Serde's behaviour, or if you're just not using Serde.

### Schema from Example Value

If you want a schema for a type that can't/doesn't implement `JsonSchema`, but does implement `serde::Serialize`, then you can generate a JSON schema from a value of that type. However, this schema will generally be less precise than if the type implemented `JsonSchema` - particularly when it involves enums, since schemars will not make any assumptions about the structure of an enum based on a single variant.

```rust
use schemars::schema_for_value;
use serde::Serialize;

#[derive(Serialize)]
pub struct MyStruct {
    pub my_int: i32,
    pub my_bool: bool,
    pub my_nullable_enum: Option<MyEnum>,
}

#[derive(Serialize)]
pub enum MyEnum {
    StringNewType(String),
    StructVariant { floats: Vec<f32> },
}

let schema = schema_for_value!(MyStruct {
    my_int: 123,
    my_bool: true,
    my_nullable_enum: Some(MyEnum::StringNewType("foo".to_string()))
});
println!("{}", serde_json::to_string_pretty(&schema).unwrap());
```

<details>
<summary>Click to see the output JSON schema...</summary>

```json
{
    "$schema": "http://json-schema.org/draft-07/schema#",
    "title": "MyStruct",
    "examples": [
        {
            "my_bool": true,
            "my_int": 123,
            "my_nullable_enum": {
                "StringNewType": "foo"
            }
        }
    ],
    "type": "object",
    "properties": {
        "my_bool": {
            "type": "boolean"
        },
        "my_int": {
            "type": "integer"
        },
        "my_nullable_enum": true
    }
}
```
</details>

## Feature Flags
- `derive` (enabled by default) - provides `#[derive(JsonSchema)]` macro
- `impl_json_schema` - implements `JsonSchema` for Schemars types themselves
- `preserve_order` - keep the order of struct fields in `Schema` and `SchemaObject`

## Optional Dependencies
Schemars can implement `JsonSchema` on types from several popular crates, enabled via optional dependencies (dependency versions are shown in brackets):
- [`chrono`](https://crates.io/crates/chrono) (^0.4)
- [`indexmap`](https://crates.io/crates/indexmap) (^1.2)
- [`either`](https://crates.io/crates/either) (^1.3)
- [`uuid`](https://crates.io/crates/uuid) (^0.8)
- [`smallvec`](https://crates.io/crates/smallvec) (^1.0)
- [`arrayvec`](https://crates.io/crates/arrayvec) (^0.5)
- [`url`](https://crates.io/crates/url) (^2.0)
- [`bytes`](https://crates.io/crates/bytes) (^1.0)
- [`enumset`](https://crates.io/crates/enumset) (^1.0)
- [`rust_decimal`](https://crates.io/crates/rust_decimal) (^1.0)
- [`bigdecimal`](https://crates.io/crates/bigdecimal) (^0.3)

For example, to implement `JsonSchema` on types from `chrono`, enable it as a feature in the `schemars` dependency in your `Cargo.toml` like so:

```toml
[dependencies]
schemars = { version = "0.8", features = ["chrono"] }
```
*/

/// The map type used by schemars types.
///
/// Currently a `BTreeMap` or `IndexMap` can be used, but this may change to a different implementation
/// with a similar interface in a future version of schemars.
/// The `IndexMap` will be used when the `preserve_order` feature flag is set.
#[cfg(not(feature = "preserve_order"))]
pub type Map<K, V> = std::collections::BTreeMap<K, V>;
#[cfg(feature = "preserve_order")]
pub type Map<K, V> = indexmap::IndexMap<K, V>;
/// The set type used by schemars types.
///
/// Currently a `BTreeSet`, but this may change to a different implementation
/// with a similar interface in a future version of schemars.
pub type Set<T> = std::collections::BTreeSet<T>;

/// A view into a single entry in a map, which may either be vacant or occupied.
//
/// This is constructed from the `entry` method on `BTreeMap` or `IndexMap`,
/// depending on whether the `preserve_order` feature flag is set.
#[cfg(not(feature = "preserve_order"))]
pub type MapEntry<'a, K, V> = std::collections::btree_map::Entry<'a, K, V>;
#[cfg(feature = "preserve_order")]
pub type MapEntry<'a, K, V> = indexmap::map::Entry<'a, K, V>;

mod flatten;
mod json_schema_impls;
mod ser;
#[macro_use]
mod macros;

/// This module is only public for use by `schemars_derive`. It should not need to be used by code
/// outside of `schemars`, and should not be considered part of the public API.
#[doc(hidden)]
pub mod _private;
pub mod gen;
pub mod schema;
pub mod visit;

#[cfg(feature = "schemars_derive")]
extern crate schemars_derive;
#[cfg(feature = "schemars_derive")]
pub use schemars_derive::*;

// Export serde_json so schemars_derive can use it
#[doc(hidden)]
pub use serde_json as _serde_json;

use schema::Schema;

/// A type which can be described as a JSON Schema document.
///
/// This is implemented for many Rust primitive and standard library types.
///
/// This can also be automatically derived on most custom types with `#[derive(JsonSchema)]`.
///
/// # Example
/// ```
/// use schemars::{schema_for, JsonSchema};
///
/// #[derive(JsonSchema)]
/// struct MyStruct {
///     foo: i32,
/// }
///
/// let my_schema = schema_for!(MyStruct);
/// ```
pub trait JsonSchema {
    /// Whether JSON Schemas generated for this type should be re-used where possible using the `$ref` keyword.
    ///
    /// For trivial types (such as primitives), this should return `false`. For more complex types, it should return `true`.
    /// For recursive types, this **must** return `true` to prevent infinite cycles when generating schemas.
    ///
    /// By default, this returns `true`.
    fn is_referenceable() -> bool {
        true
    }

    /// The name of the generated JSON Schema.
    ///
    /// This is used as the title for root schemas, and the key within the root's `definitions` property for subschemas.
    fn schema_name() -> String;

    /// Generates a JSON Schema for this type.
    ///
    /// If the returned schema depends on any [referenceable](JsonSchema::is_referenceable) schemas, then this method will
    /// add them to the [`SchemaGenerator`](gen::SchemaGenerator)'s schema definitions.
    ///
    /// This should not return a `$ref` schema.
    fn json_schema(gen: &mut gen::SchemaGenerator) -> Schema;

    // TODO document and bring into public API?
    #[doc(hidden)]
    fn _schemars_private_non_optional_json_schema(gen: &mut gen::SchemaGenerator) -> Schema {
        Self::json_schema(gen)
    }

    // TODO document and bring into public API?
    #[doc(hidden)]
    fn _schemars_private_is_option() -> bool {
        false
    }
}

#[cfg(test)]
pub mod tests {
    use super::*;

    pub fn schema_object_for<T: JsonSchema>() -> schema::SchemaObject {
        schema_object(schema_for::<T>())
    }

    pub fn schema_for<T: JsonSchema>() -> schema::Schema {
        let mut gen = gen::SchemaGenerator::default();
        T::json_schema(&mut gen)
    }

    pub fn schema_object(schema: schema::Schema) -> schema::SchemaObject {
        match schema {
            schema::Schema::Object(o) => o,
            s => panic!("Schema was not an object: {:?}", s),
        }
    }
}