because "this.studentMapper" is null
时间: 2023-12-12 18:03:01 浏览: 41
The error message "this.studentMapper is null" means that the variable "studentMapper" is not initialized properly. There could be several reasons why this is happening, but most likely it is because you have not instantiated the object or you have not set the object to a valid value.
To fix this error, you need to ensure that the "studentMapper" object is properly initialized before it is used. Here are some steps you can take to troubleshoot the issue:
1. Check that the "studentMapper" object is declared and initialized properly. Make sure you have declared the object and assigned it to a valid value.
2. Check that the "studentMapper" object is being injected properly. If you are using dependency injection, ensure that the object is being injected correctly.
3. Check that the "studentMapper" object is being initialized before it is used. If the object is being initialized asynchronously, ensure that it is fully initialized before it is used.
4. Check that the "studentMapper" object is not being overwritten or set to null in another part of the code.
By following these steps, you should be able to identify the root cause of the error and fix it accordingly.