# Database Management

## Example

```java
public class ExampleMongoProvider implements DatabaseProvider<Example> {

    private final MongoClient client;
    private final String databaseName;
    private MongoCollection<BsonDocument> collection;

    public ExampleMongoProvider(String ip, int port, String username, String password, String databaseName) {
        MongoClientURI clientURI = !username.equals("") ? new MongoClientURI("mongodb://" + ip + ":" + port + "@" + username + ":" + password) : new MongoClientURI("mongodb://" + ip + ":" + port);
        this.client = new MongoClient(clientURI);
        this.databaseName = databaseName;
    }

    @Override
    public void create() {
        MongoDatabase mongoDatabase = this.client.getDatabase(this.databaseName);
        if (!mongoDatabase.listCollectionNames().into(new ArrayList<>()).contains("example"))
            mongoDatabase.createCollection("example");
        this.collection = mongoDatabase.getCollection("example", BsonDocument.class);
    }

    @Nonnull
    @Override
    public List<Example> getValues() {
        List<Example> examples = new ArrayList<>();
        this.collection.find().into(new ArrayList<>())
                .forEach(document -> examples.add(new example(document)));
        return examples;
    }

    @Nonnull
    @Override
    public Example getValue(@Nonnull String key, @Nonnull Object value) {
        String valueString = value.toString();
        BsonDocument document = this.collection.find(new BsonDocument(key, new BsonString(valueString))).first();
        if (document == null)
            throw new IllegalArgumentException("no example with key " + key + " and value " + valueString + " found.");
        return new Example(document);
    }

    @Override
    public void insert(@Nonnull Example example) {
        this.collection.insertOne(Example.toBsonDocument());
    }

    @Override
    public void update(@Nonnull Example example) {
        this.collection.updateOne(this.toSelectDocument(example), new BsonDocument("$set", example.toBsonDocument()));
    }

    @Override
    public void delete(@Nonnull Example example) {
        this.collection.deleteOne(this.toSelectDocument(example));
    }

    @Override
    public void insert(@Nonnull Collection<Example> examples) {
        if (examples.size() == 0)
            return;

        List<WriteModel<BsonDocument>> writes = new ArrayList<>();
        examples.forEach(example -> writes.add(new InsertOneModel<>(example.toBsonDocument())));
        this.collection.bulkWrite(writes);
    }

    @Override
    public void update(@Nonnull Collection<Example> examples) {
        if (examples.size() == 0)
            return;

        List<WriteModel<BsonDocument>> writes = new ArrayList<>();
        examples.forEach(example -> writes.add(new UpdateOneModel<>(this.toSelectDocument(examples), new BsonDocument("$set", example.toBsonDocument()))));
        this.collection.bulkWrite(writes);
    }

    @Override
    public void delete(@Nonnull Collection<Example> examples) {
        if (examples.size() == 0)
            return;

        List<WriteModel<BsonDocument>> writes = new ArrayList<>();
        examples.forEach(example -> writes.add(new DeleteOneModel<>(this.toSelectDocument(example))));
        this.collection.bulkWrite(writes);
    }


    /*
    Converter from Example.class to document.
     */
    private BsonDocument toSelectDocument(Example example) {
        return new BsonDocument(ExampleMongoField.UID.getPath(), ExampleMongoField.UID.getValue(example));
    }
}
```


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