Gin uses for validation. Check the full docs on tags usage here.

Note that you need to set the corresponding binding tag on all fields you want to bind. For example, when binding from JSON, set .

  • Type - Should bind
    • Methods - ShouldBind, ShouldBindJSON, ShouldBindQuery
    • Behavior - These methods use under the hood. If there is a binding error, the error is returned and it is the developer’s responsibility to handle the request and error appropriately.

When using the Bind-method, Gin tries to infer the binder depending on the Content-Type header. If you are sure what you are binding, you can use MustBindWith or ShouldBindWith.

You can also specify that specific fields are required. If a field is decorated with binding:"required" and has a empty value when binding, an error will be returned.

  1. $ curl -v -X POST \
  2.   http://localhost:8080/loginJSON \
  3.   -d '{ "user": "manu" }'
  4. > POST /loginJSON HTTP/1.1
  5. > Host: localhost:8080
  6. > User-Agent: curl/7.51.0
  7. > Accept: */*
  8. > content-type: application/json
  10. * upload completely sent off: 18 out of 18 bytes
  11. < HTTP/1.1 400 Bad Request
  12. < Content-Type: application/json; charset=utf-8
  13. < Date: Fri, 04 Aug 2017 03:51:31 GMT
  14. < Content-Length: 100
  15. <
  16. {"error":"Key: 'Login.Password' Error:Field validation for 'Password' failed on the 'required' tag"}

Skip validate

When running the above example using the above the curl command, it returns error. Because the example use binding:"required" for Password. If use binding:"-" for , then it will not return error when running the above example again.