如何使用Javascript从字符串中间提取然后重新格式化文本？

Question

I have named the constraints in my database like "FK_ChildParent". When I have a foreign key error caused by an admin person trying to delete a row with children then I get messages like this:

exceptionMessage=The DELETE statement conflicted with the REFERENCE constraint "FK_ContentSubject". The conflict occurred in database "xx", table "dbo.Content", column 'SubjectId'.
The statement has been terminated.

Is there an easy way that I can translate this message into something like:

"Delete failed: Row has Content"

I would really like to find a one line solution but I am not sure if this is possible.

Answer 1

When you get a MySQL constraint error like this, it means there is a problem in your code. Your code is trying to do something it shouldn't. You're trying to rely on MySQL to tell you what your code did wrong, but MySQL has no idea because it just knows about tables and fields and constraints.

If your desired error message is something like: "Can't delete folder, there are still files in the folder" ; ie. an fk exists for a record you're trying to delete. You wont be able to get it by some clever string replacement, especially if the error messages get more complex or you might have multiple queries per request.

You have to check the foreign key constraint yourself, because it's tied to some implicit business rule ; ie. you can't delete a folder if there are files in it. Test the business rule, if it fails you'll know exactly what went wrong.

The MySQL-level constraint just helps you to make sure your data has some semblance of consistency, but don't rely on it.