BeforeCreate and BeforeUpdate run Encrypt on whatever is in the struct,
and a user read from the database carries the stored hash in Password.
Hashing it again produces a hash of a hash: the password that user knows
stops matching, they cannot log in, and nothing reports an error.
Only the Omit("password") on SysUser.Update stood between that and the
stored credential. Any other write to this model - a profile update
written the way every other model here is written - destroys the
password, permanently and silently.
Encrypt now returns early when Password already parses as a bcrypt hash.
That also removes the round SysUser.Update was paying and discarding:
306ns where it was 54.7ms, on a route reachable without the permission
check, since PUT /api/v1/sys-user is in CasbinExclude.
The cost of deciding from the value is that a password which is itself a
well-formed bcrypt hash would be stored unchanged. That is a
60-character string beginning "$2a$", and it grants whoever set it no
access they did not already have.
zhangwenjian