Access to MongoDB database using PONGO

When to use ?

This guideline present how to the CROSSMINER Platform can access to his data stored in a MongoDb data base. The guideline describe how to create a connection to the MongoDb database and how to perform CRUD operation on platform datas.

Context

The CROSSMINER platform use a MongoDb data base to store his data. We go through PONGO, a template based Java POJO generator to access MongoDB database. With Pongo we can define the data model which generates strongly-typed Java classes.

In this guideligne, we will present :

• The access to MongoDb Document on from aneclipse plugin integrate to the CROSSMINER platform.
• The access to MongoDb Document on from an external Java application.
• How to preform basic CRUD operation with a PONGO Java data model.

We consider that the PONGO Java data model already exist. If it's not the case , please refer the fooling guideline to create the data model : https://github.com/crossminer/crossminer/wiki/Extend-MongoDB-Data-Model

You want to access to MongoDB Document from an Eclipse Plugin ?

1. Add a dependency to the Java Data Model

• Edit the plugin.xml file of your plugin.
• In Dependency section, add a dependency to the plugin which contained the data model you went to access.
  • To org.ossmeter.repository.model to access data related to project administration , metric execution process and authentification system.
  • To org.ossmeter.repository.model.'project delta manager' to access configuration informations related to source codes managemeny tools.
  • To specific metric provider plugins to access data related to a specific metric provider implementation contains his once data model.
  • ... others plugin which contained the data model
• In Dependency section, add a dependency to com.googlecode.pongo.runtime plugin

2. Initiate a Connection to the MongoDb

In context of the CROSSMINER platform, a Configuration service allow you to initiate a connection whit the mongoDb data base.

• In Dependency section of plugin.xml file , add a dependency to the org.ossmeter.platform plugin.
• You can now create a new connection to the database using the Configuration service.

Mongo mongo = Configuration.getInstance().getMongoConnection(); 

You want to access to MongoDB Document on from an External Java Application ?

1. Add a dependency to the Java Data Model

• Add to your java project a dependency to the jar which contained the data model you went to access. You will have to deliver this jar with your application.

• Add o your java project a dependency to the pongo.jar jar file which can be download at this url : https://github.com/kolovos/pongo/releases

2. Initiate a Connection to MongoDb

// Define ServerAddress of the MongoDb database
List<ServerAddress> mongoHostAddresses = new ArrayList<>();
mongoHostAddresses.add(new ServerAddress(s[0], Integer.valueOf(s[1])));

// Create Connection
Mongo mongo = new Mongo(mongoHostAddresses);

Once the connection to MongoDb has been created, you have to make the link between the PONGO Java model and the database. On a MongoDb Server, data are organize by database. You need to know the name of the database to link the Java model with the MongoDb document.

DB db =  mongo.getDB("databasename");

// Initiate the Project Java model
ProjectRepository = new ProjectRepository(db);

Basic CRUD with a PONGO Java data model

1. CREATE

// Connect the Data model to the database
DB db =  mongo.getDB("databasename");
MetricProvider metricprovider = new MetricProvider(db);

// Used accessors to intialise the object
metricprovider.setName("Metric1").
......
 
// Create the Document
metricprovider.sync(true);

2. READ

// Connect the Data model to the database
DB db =  mongo.getDB("databasename");
MetricProvider metricprovider = new MetricProvider(db);

// Used accessors to access object properties
metricprovider.getname();
......

3. UPDATE

// Connect the Data model to the database
DB db =  mongo.getDB("databasename");
MetricProvider metricprovider = new MetricProvider(db);

// Used accessors to intialise the object
metricprovider.setName("Metric1").
......
 
// Create the Document
metricprovider.sync(true);

4. DELETE

Mongo mongo = new Mongo(); mongo.dropDatabase("databasename");

Comment

This wiki has dealt with the access of MongoDB database using PONGO. To continue learning how to modify and make a new model with Pongo, we have another page here link .