RUST-1048 support something like get_default_database from client?

[WindSoilder]

Let's say that I have the following code:

use mongodb::sync::Client;
let cli = Client::with_uri_str("mongodb://localhost:21017/test_db").unwrap();

It's good that we can fetch default database like this:

assert_eq!(cli.get_default_databse(), Some("test_db"));

If I have the following code:

use mongodb::sync::Client;
let cli = Client::with_uri_str("mongodb://localhost:21017/").unwrap();

then cli.get_default_database can return None.

Connection string reference: https://docs.mongodb.com/manual/reference/connection-string/

[patrickfreed]

Hi @WindSoilder, thanks for the suggestion! Could you provide an example use case for this? For some context, in drivers (as opposed to the shell), the default database isn't used for much besides being the default auth source for certain auth mechanisms (e.g. SCRAM-SHA-256).

[WindSoilder]

It's mainly used for application config or cli arguments.

Let's take mongodump as example, we can use mongodump like this:

mongodump --uri="mongodb://mongodb0.example.com:27017/test_db"

To dump only test_db, if we don't have the feature to get default datbaase, we have to use it like this:

mongodump --uri="mongodb://mongodb0.example.com:27017/" --db test_db

which is more complicated than the first one. For application involves more database instance, we can just use many urls for each mongodb instance, rather than specific every database explicitly

[patrickfreed]

Makes sense, I filed RUST-1048 to discuss with the team at our triage meeting on Monday. Thanks again for filing this issue!

[patrickfreed]

After discussing with the team, we agree that this would be a useful feature to have. We're not sure when we'll be able to get around to implementing it, but we'd be happy to accept a pull request if you were interesting in contributing it!

We think the API changes would include the following:

• A new Option<String> on ClientOptions called default_database
• A new method on Client called default_database(&self) -> Option<&str>
  • Though, I wonder if this would be more ergonomic if it actually returned an Option<Database>

Let me know if you have any other questions!