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I'm developing a web application in Node.js with MongoDB as the back end. What I wanted to know is, what is the generally accepted procedure, if any exists, for creating initial collections and populating them with initial data such as a white list for names or lists of predefined constants.

From what I have seen, MongoDB creates collections implicitly any time data is inserted into the database and the collection being inserted into doesn't already exist. Is it standard to let these implicit insertions take care of collection creation, or do people using MongoDB have scripts setup which build the main structure and insert any required initial data? (For example, when using MySQL I'd have a .sql script which I can run to dump and rebuild /repopulate the database from scratch).

Thank you for any help.

MHY

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mhy
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2 Answers2

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If you have data, this post on SO might be interresting for you. But since Mongo understands JavaScript, you can easily write a script that prepares the data for you.

It's the nature of Mongo to create everything that does not exist. This allows a very flexible and agile development since you are not constrainted to types or need to check if table x already exists before working on it. If you need to create collections dynamically, just get it from the database and work it if (no matter if it exists or not).

If you are looking for a certain object, be sure to check it (not null or if a certain key exists) because it may affect your code if you work with null objects.

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DrColossos
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  • Thanks :) I guess that is the whole advantage of using Mongo. – mhy Aug 15 '11 at 15:48
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    I would like to comment that, although Mongo will do database and collection creation on an as needed basis, there is still a role for old-school "drop/create" scripts in Mongo applications. In particular, and given the importance of indexes and the cost of their creation on a live system, I strongly recommend the creation of createDatabase.js scripts to get the indexes in place before the data starts flowing in. – Bob Kuhar Oct 08 '12 at 21:27
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There's is absolutely no reason to use setup scripts merely to make collections and databases appear. Both DB and collection creation is done lazily.

Rember that MongoDB is a completely schema free document store so there's no way to even setup a specific schema in advance.

There are tools available to dump and restore database content supplied with mongo.

Now, if your application needs initial data (like configuration parameters or whitelists like you suggest) it's usually best practice to have your application components set up there own data as needed and offer data migration paths as well.

Remon van Vliet
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  • Thank you, I guess I'll let Mongo take care of it. I'm not sure what you mean by having application components set up their own data, but perhaps it means keeping a config file or two around...? – mhy Aug 15 '11 at 15:53