ch.agent.crnickl.mongodb.WriteMethodsForProperty.java Source code

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Here is the source code for ch.agent.crnickl.mongodb.WriteMethodsForProperty.java

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/*
 *   Copyright 2012-2013 Hauser Olsson GmbH
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 */
package ch.agent.crnickl.mongodb;

import org.bson.types.ObjectId;

import ch.agent.crnickl.T2DBException;
import ch.agent.crnickl.T2DBMsg;
import ch.agent.crnickl.T2DBMsg.E;
import ch.agent.crnickl.api.Property;
import ch.agent.crnickl.api.Surrogate;
import ch.agent.crnickl.impl.Permission;
import ch.agent.crnickl.impl.SchemaUpdatePolicy;

import com.mongodb.BasicDBObject;
import com.mongodb.DBCollection;
import com.mongodb.WriteConcern;

/**
 * A stateless object with methods providing write access to properties.
 * <p>
 * A property in MongoDB is stored as:
 * <blockquote><pre><code>
 * { _id : OID, 
 *   name : STRING, 
 *   type : OID, 
 *   indexed : BOOLEAN 
 * }
 * </code></pre></blockquote>
 * The <em>type</em> field identifies the value type.
 * <p>
 * @author Jean-Paul Vetterli
 */
public class WriteMethodsForProperty extends ReadMethodsForProperty {

    public WriteMethodsForProperty() {
    }

    /**
     * Create a new property and return its key. 
     * If creation fails throw an exception.
     * 
     * @param prop a property
     * @throws T2DBException
     */
    public <T> void createProperty(Property<T> prop) throws T2DBException {
        Surrogate surrogate = null;
        Throwable cause = null;
        try {
            check(Permission.CREATE, prop);
            BasicDBObject dob = pack(prop);
            getMongoDB(prop).getProperties().insert(dob);
            ObjectId ox = getObjectId(dob);
            surrogate = makeSurrogate(prop, new MongoDBObjectId(ox));
        } catch (Exception e) {
            cause = e;
        } finally {
        }
        if (surrogate == null || cause != null)
            throw T2DBMsg.exception(cause, E.E20114, prop.getName());
        prop.getSurrogate().upgrade(surrogate);
    }

    /**
     * Delete the property.
     * If deleting fails throw an exception.
     * 
     * @param prop a property
     * @param policy a schema updating policy
     * @throws T2DBException
     */
    public <T> void deleteProperty(Property<T> prop, SchemaUpdatePolicy policy) throws T2DBException {
        boolean done = false;
        Throwable cause = null;
        Surrogate s = prop.getSurrogate();
        MongoDatabase database = (MongoDatabase) s.getDatabase();
        try {
            check(Permission.MODIFY, prop);
            // dangerous update! see comment in MongoDatabase.sleep
            policy.willDelete(prop);
            Property<T> original = database.getReadMethodsForProperty().getProperty(s);
            DBCollection coll = getMongoDB(s).getProperties();
            coll.remove(asQuery(s.getId()), WriteConcern.SAFE);
            database.sleep();
            try {
                policy.willDelete(original);
            } catch (T2DBException e) {
                createProperty(original);
                throw e;
            }
            done = true;
        } catch (Exception e) {
            cause = e;
        } finally {
        }
        if (!done || cause != null)
            throw T2DBMsg.exception(cause, E.E20115, prop.getName());
    }

    /**
     * Update the name of the property.
     * If updating fails throw an exception.
     * 
     * @param prop a property
     * @param policy a schema updating policy
     * @throws T2DBException
     */
    public void updateProperty(Property<?> prop, SchemaUpdatePolicy policy) throws T2DBException {
        boolean done = false;
        Throwable cause = null;
        Surrogate s = prop.getSurrogate();
        try {
            check(Permission.MODIFY, prop);
            DBCollection coll = getMongoDB(s).getProperties();
            coll.update(asQuery(s.getId()), operation(Operator.SET, MongoDatabase.FLD_PROP_NAME, prop.getName()));
            done = true;
        } catch (Exception e) {
            cause = e;
        } finally {
        }
        if (!done || cause != null)
            throw T2DBMsg.exception(cause, E.E20116, prop.getName());
    }

    /**
     * Packs a property into a BSON object.
     * 
     * @param prop a Property
     * @return a BasicDBObject
     */
    private <T> BasicDBObject pack(Property<T> prop) {
        com.mongodb.BasicDBObject bo = new BasicDBObject();
        if (!prop.getSurrogate().inConstruction())
            bo.put(MongoDatabase.FLD_ID, getId(prop));
        bo.put(MongoDatabase.FLD_PROP_NAME, prop.getName());
        bo.put(MongoDatabase.FLD_PROP_VT, getId(prop.getValueType()));
        bo.put(MongoDatabase.FLD_PROP_INDEXED, prop.isIndexed());
        return bo;
    }

}