Very basic java client for the CouchDB 2.0 database server.
Maven dependency:
<dependency>
<groupId>net.uiqui</groupId>
<artifactId>couchdb-client</artifactId>
<version>0.5.0</version>
</dependency>Single node cluster:
// Using default port and no credentials
CouchClient couchDB = CouchClient.build("localhost");
// No credentials
CouchClient couchDB = CouchClient.build("localhost", 5984);
// Full control
CouchClient couchDB = CouchClient.build("localhost", 5984, "user", "password");Multi node cluster:
CouchClient couchDB = new CouchClient.Builder()
.node("node1", 5984)
.node("node2") // Use default port
.user("admin")
.password("admin")
.build();When supplied more than one node the API will choose randomly one node as the active node. If case of a SocketTimeoutException exception the API will try another node (transparently).
To have access to the CRUD operations we must identify the database by creating a net.uiqui.couchdb.api.DB object.
DB testDB = couchDB.database("test");
// Of the database object will be used only to manipulate a specific object type, we can use the TypedDB class instead
TypedDB<User> userDB = couchDB.database("users", User.class);The documents to be saved on CouchDB must extend the net.uiqui.couchdb.api.Document class, this class provides to fields the ID and REVISION representing the "_id" and "_rev" fields on CouchDB.
public class User extends Document {
private String email = null;
private String name = null;
private List<String> roles = new ArrayList<String>();
public User() {
super();
}
public User(String id, String revision) {
super(id, revision);
}
public User(String id) {
super(id);
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<String> getRoles() {
return roles;
}
public void addRole(String role) {
roles.add(role);
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder();
builder.append("User(id=");
builder.append(getId());
builder.append(", revision=");
builder.append(getRevision());
builder.append(", email=");
builder.append(email);
builder.append(", name=");
builder.append(name);
builder.append(", roles=");
builder.append(roles);
builder.append(")");
return builder.toString();
}
}To have access to the CRUD operations we must identify the database by creating a net.uiqui.couchdb.api.DB object.
// Lets check id the admin user already exists
System.out.println(userDB.contains("admin"));
// Output: false
// Lets create some User objects
User admin = new User();
admin.setId("admin"); // We can set the document ID
admin.setName("System Admin");
admin.setEmail("[email protected]");
admin.addRole("admin");
admin.addRole("user");
User oper1 = new User(); // If we don't provide a value for the ID, CouchDB will provide a unique ID
oper1.setName("Operator 1");
oper1.setEmail("[email protected]");
oper1.addRole("operations");
oper1.addRole("user");
// Lets see the objects
System.out.println(admin); // No value for REVISION
// Output: User(id=admin, revision=null, [email protected], name=System Admin, roles=[admin, user])
System.out.println(oper1); // No values for ID and REVISION
// Output: User(id=null, revision=null, [email protected], name=Operator 1, roles=[operations, user])
// Add the objects to the database
userDB.save(admin);
userDB.save(oper1);
// The object now already has values for ID and REVISION
System.out.println(admin);
// Output: User(id=admin, revision=15-723fb4317336edfdbcca68e9490bbd23, [email protected], name=System Admin, roles=[admin, user])
System.out.println(oper1);
// Output: User(id=21639faca07a48a02a905d6cfe002d33, revision=1-e0eadad7c6127f2bd9d0f6f2234e1929, [email protected], name=Operator 1, roles=[operations, user])
// Lets check id the admin user already exists on the database
System.out.println(userDB.contains("admin"));
// Output: true
// Lets retrieve the object from the database
User administrator = userDB.get("admin");
// Same object than admin
System.out.println(administrator);
// Output: User(id=admin, revision=15-723fb4317336edfdbcca68e9490bbd23, [email protected], name=System Admin, roles=[admin, user])
//Lets change the objects
administrator.addRole("support");
oper1.addRole("support");
// And update objects on the database
userDB.save(admin);
userDB.save(oper1);
// The REVISION field was changed
System.out.println(admin);
// Output: User(id=admin, revision=16-2e71da8ace356ea126eb0538793ef2c7, [email protected], name=System Admin, roles=[admin, user])
System.out.println(oper1);
// Output: User(id=21639faca07a48a02a905d6cfe002d33, revision=2-80922fc0581053a218048c8a6853505f, [email protected], name=Operator 1, roles=[operations, user, support])
// Lets retrieve the object again
User tmp = userDB.get("admin");
// Same object than oper
System.out.println(tmp);
// Output: User(id=admin, revision=16-2e71da8ace356ea126eb0538793ef2c7, [email protected], name=System Admin, roles=[admin, user])
// Lets delete the documents
userDB.remove("admin"); // We can delete the object, by providing the only the ID or by providing the ID and the REVISION
userDB.remove(oper1);
// Lets check id the admin user still exists on the database
System.out.println(userDB.contains("admin"));
// Output: falseTo execute a view we must create a ViewRequest:
// Number of user by role
ViewRequest request1 = new ViewRequest.Builder("test", "roles")
.group(true)
.build();
ViewResult result1 = userDB.execute(request1);
System.out.println("Users by role:");
for (Row row : result1.rows()) {
System.out.println(row.key() + " - " + row.value());
}
/* Output:
Users by role:
admin - 1.0
operations - 1.0
support - 2.0
user - 2.0
*/
// List of users with role "user"
ViewRequest request2 = new ViewRequest.Builder("test", "roles")
.reduce(false)
.keys("user")
.build();
ViewResult result2 = userDB.execute(request2);
System.out.println("Users with role 'user':");
for (Row row : result2.rows()) {
User user = userDB.get(row.id());
System.out.println(user);
}
/* Output:
Users with role 'user':
User(id=admin, revision=34-390fb1ace6d6dd28e43d870dcbe19505, [email protected], name=System Admin, roles=[admin, user, support])
User(id=oper1, revision=11-b08b7cc75a0da78ad86504608e27a76e, [email protected], name=Operator 1, roles=[operations, user, support])
*/