Multiple MongoDB databases using Spring Data example

This example shows how to interact with multiple MongoDB databases using Spring Data.

It employs the analogy of a market with products it has to offer. The products and market are separate entities and on purpose reside in separate data stores.

Interestingly this is very similar to a very real world market, in a real world stock exchange (market) people/companies purchase instruments (products). Market participants do not need to know everything about the instrument, rather they need to identify the instrument and they are typically concerned about the price on the day. Most of these instruments are referenced using well known identifiers e.g. CUSIP, ISIN, etc.

Databases

• Market
• Product

Collection names are the same as the database names.

Branch "spring-data-mongodb-1.0.0.RELEASE_dbref_association_same_database"

The product to market association is by id, meaning that product is saved in it's the same database and referenced by id in the market collection. This is exactly what we want and works when retrieving the associated product entities on market and both are in the same database.

References:

• [MongoDB] (http://www.mongodb.org)
• [Spring Data MongoDB] (http://www.springsource.org/spring-data/mongodb)
• Stock Exchanges
• Instrument
• ISIN