JSON decode errors

This example demonstrates how to return useful error messages to the client when the server receives a request with invalid JSON, or which cannot be deserialized to the expected model. By configuring an error_handler on the route, we can set appropriate response codes and return the string representation of the error.

Usage

cd examples/json_decode_error
cargo run
# Started HTTP server: 127.0.0.1:8088

Examples

The examples use curl -i in order to show the status line with the response code. The response headers have been omitted for brevity, and replaced with an ellipsis ....

• A well-formed request

  $ curl -i 127.0.0.1:8088 -H 'Content-Type: application/json' -d '{"name": "Alice"}'
  HTTP/1.1 200 OK
  ...
  
  Hello Alice! 

• Missing Content-Type header

  $ curl -i 127.0.0.1:8088 -d '{"name": "Bob"}'
  HTTP/1.1 415 Unsupported Media Type
  ...
  
  Content type error

• Malformed JSON

  $ curl -i 127.0.0.1:8088 -H 'Content-Type: application/json' -d '{"name": "Eve}'
  HTTP/1.1 400 Bad Request
  ...
  
  Json deserialize error: EOF while parsing a string at line 1 column 14

• JSON value of wrong type

  $ curl -i 127.0.0.1:8088 -H 'Content-Type: application/json' -d '{"name": 350}'
  HTTP/1.1 422 Unprocessable Entity
  ...
  
  Json deserialize error: invalid type: integer `350`, expected a string at line 1 column 12

• Wrong JSON key

  $ curl -i 127.0.0.1:8088 -H 'Content-Type: application/json' -d '{"namn": "John"}'
  HTTP/1.1 422 Unprocessable Entity
  ...
  
  Json deserialize error: missing field `name` at line 1 column 16

More documentation

actix_web::web::JsonConfig