Introducing Spring Framework

Chapter 15
Spring Data Within Your Spring
Application
So far your Spring application has some basic features, enough to demonstrate the capabilities of the Spring
Framework. But imagine for a moment that you need to add more attributes to the model, maybe something like
tags or keywords to the documents. It should be easy enough to add the attributes and modify the DAOs and/or SQL
statements, right? For easy attributes, maybe it is, but what happens if you require more complicated relationships or
more attributes every week? It would be a tedious job to change it all the time.
Fortunately, there are NoSQL databases, which provide features like adding more attributes to a persistence
object without adding or modifying schemas. In this chapter, you are going to add a NoSQL database: MongoDB.
Using NoSQL Databases
MongoDB is a document-oriented database system that makes the integration of data very easy; it persists objects
using a JSON-like style and creates collections of this data. Let’s add this new feature to your Spring application.
The Spring Framework provides a module for NoSQL databases: Spring Data. Before you continue, you need
to make sure you have installed the MongoDB server on your computer. (For more information about how to install
MongoDB, see Appendix A.) See Listing 15-1 for the modification of the Document class.
Listing 15-1. Document.java
package com.apress.isf.java.model;
import java.util.Date;
import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.DBRef;
@org.springframework.data.mongodb.core.mapping.Document(collection="docs")
public class Document {
@Id
private String documentId;
private String name;
@DBRef
private Type type;
private String location;
private String description;
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