This page is for the current v1 alpha version of Schemars. This version is still under development, and further breaking changes may be introduced.

To view this page for the current stable release of Schemars (v0.8.x), 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"
          ]
        }
      ]
    }
  }
}