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Tiger Wang
26,548 PointsCan't run 'db.rename' on Mongodb
Hey guys:
It's about the Quiz, What command can be used to rename a database. And the answer goes to 'rename'. But I've tried every option in the list, included 'name' & 'mv'. The response is always :
TypeError: db.rename is not a function :
@(shell):1:1
There's no 'rename' function for db in Mongo's API Docs. I found this Jira post about 'rename database' ,here: Ability to rename databases
Should I use copyDatabase instead of rename it or any other better suggestion?
PS: Strongly suggesting to add a link about 'markdown syntax' on write new post/question/discuss.
Robert Komaromi
11,927 PointsThanks Ken. I just needed closure about this error - a quick Google search for 'how to rename a database in mongodb' gives me many answers. But double checking myself when I get an unexpected answer is a nice way to learn :p
Tiger Wang
26,548 PointsThanks for both of you, guys. I already took 'copyDatabase' as the answer.
5 Answers
Ken Alger
Treehouse TeacherTiger;
You are correct! Nice catch, I missed it myself going through the course and in QA. 
renameCollection() function.
Happy coding,
Ken
Dakota Bryant
3,903 PointsHuston, it appears that the question is still in this course, with no reference to Mongo Hacker inside of the videos leading up. Is that intentional?
corysimmons2
1,071 PointsJust a reminder for QA. This broken question is still in the quiz for https://teamtreehouse.com/library/mongo-basics/working-with-collections/review-managing-collections
Ken Alger
Treehouse TeacherRobert;
As I mentioned, renaming a database in MongoDB is, while not too complicated, a bit more effort that simply calling a rename function. The quickest method I have found to do so is:
db.copyDatabase(“db_to_rename”,”db_renamed”,”localhost”)
use db_to_rename
db.dropDatabase();
There are other solutions available, but for most situations I have found the above method to be efficient.
Ken
Huston Hedinger
Treehouse Guest TeacherHey guys - you are right - db.rename does not come packaged with the mongo shell. It does come with Mongo Hacker!
To tell you the truth, I did not realize that when I was creating the course and I apologize for the confusion.
In case you are interested, here is the mongo-hacker code that adds the rename method.
DB.prototype.rename = function(newName) {
if(newName == this.getName() || newName.length === 0)
return;
this.copyDatabase(this.getName(), newName, "localhost");
this.dropDatabase();
db = this.getSiblingDB(newName);
};
As Ken Alger pointed out, it uses the copyDatabase and dropDatabase.
Robert Komaromi
11,927 PointsRobert Komaromi
11,927 PointsI had the same question! Also, if you look through the docs, you'll see there is no name/rename/mv database function.