This page is for the current stable release of Schemars (v0.8.x).

To view this page for the v1 version of Schemars, which is still under development, click here.

Using Serde Attributes

#[serde(...)] attributes can be overriden (or replaced) with #[schemars(...)] attributes, which behave identically. 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.

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

#[derive(Deserialize, Serialize, JsonSchema)]
#[schemars(rename_all = "camelCase", deny_unknown_fields, extend("x-customProperty" = "example"))]
pub struct MyStruct {
    #[serde(rename = "thisIsOverridden")]
    #[schemars(rename = "myNumber", range(min = 1, max = 10), transform = remove_format)]
    pub my_int: i32,
    pub my_bool: bool,
    #[schemars(default)]
    pub my_nullable_enum: Option<MyEnum>,
    #[schemars(inner(regex(pattern = "^x$")))]
    pub my_vec_str: Vec<String>,
}

#[derive(Deserialize, Serialize, JsonSchema)]
#[schemars(untagged)]
pub enum MyEnum {
    StringNewType(#[schemars(email)] String),
    StructVariant {
        #[schemars(length(min = 1, max = 100))]
        floats: Vec<f32>,
    },
}

fn remove_format(schema: &mut Schema) {
    schema.remove("format");
}

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

Click to see the output JSON schema...

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "MyStruct",
  "type": "object",
  "properties": {
    "myBool": {
      "type": "boolean"
    },
    "myNullableEnum": {
      "anyOf": [
        {
          "$ref": "#/$defs/MyEnum"
        },
        {
          "type": "null"
        }
      ],
      "default": null
    },
    "myNumber": {
      "type": "integer",
      "maximum": 10,
      "minimum": 1
    },
    "myVecStr": {
      "type": "array",
      "items": {
        "type": "string",
        "pattern": "^x$"
      }
    }
  },
  "additionalProperties": false,
  "required": [
    "myNumber",
    "myBool",
    "myVecStr"
  ],
  "x-customProperty": "example",
  "$defs": {
    "MyEnum": {
      "anyOf": [
        {
          "type": "string",
          "format": "email"
        },
        {
          "type": "object",
          "properties": {
            "floats": {
              "type": "array",
              "items": {
                "type": "number",
                "format": "float"
              },
              "maxItems": 100,
              "minItems": 1
            }
          },
          "required": [
            "floats"
          ]
        }
      ]
    }
  }
}