Dynamic List Constraints in Alfresco

In Alfresco Share, how do I populate the drop down values from a database. This is something possible using dynamic constraint. So here I go.

To achieve this you need to extend the "ListOfValuesConstraint" class which present in org.alfresco.repo.dictionary.constraint.ListOfValuesConstraint package.

Step-1 (Extend the class):

package org.alfresco.diary.constraint;

import java.io.Serializable;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import org.alfresco.repo.dictionary.constraint.ListOfValuesConstraint;
import javax.faces.model.SelectItem;
import org.apache.log4j.Logger;


public class CustomConstraint extends ListOfValuesConstraint implements Serializable {

   private final Logger logger = Logger.getLogger(CustomConstraint.class);
   private static final long serialVersionUID=1;

   @Override
    public void setAllowedValues(List allowedValues) {
    }

    @Override
    public void setCaseSensitive(boolean caseSensitive) {
    }

   public void initialize() {
       super.setCaseSensitive(false);
       this.getDataFromDb();
    }

    protected void getDataFromDb() {

String driverName = "org.gjt.mm.mysql.Driver";
        String serverName = "localhost:3306";
        String dbName = "alfdiary";
        String userName = "alfdiary";
        String password = "alfdiary";

        List<String> allowedValue = new ArrayList<String>();

        try {
            Connection connection = null;
            Class.forName(driverName);
            String url = "jdbc:mysql://" + serverName +  "/" + dbName;
            connection = DriverManager.getConnection(url, userName, password);
            Statement stmt = connection.createStatement();
            ResultSet rs = stmt.executeQuery("select dropdowns from alfdiary");
            while (rs.next()) {
                allowedValue.add(rs.getString("dropdowns"));
            }
        }
        catch (Exception e) {}
super.setAllowedValues(allowedValue);
   }
}

Step-2 (Create Metadata Model):

Add the following configurations in your meta model.

<constraint name="alfdiary:dropDowns" type="org.alfresco.diary.constraint.CustomConstraint">
<parameter name="allowedValues">
<list></list>
</parameter>
</constraint>

Apply the above constraint to the metadata

Thats it!!!