AbstractStorable.java

/**
 * Copyright 2016 Hortonworks.
 *
 * 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 com.hortonworks.registries.storage.catalog;

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.hortonworks.registries.common.Schema;
import com.hortonworks.registries.common.exception.ParserException;
import com.hortonworks.registries.common.util.ReflectionHelper;
import com.hortonworks.registries.storage.exception.StorageException;
import com.hortonworks.registries.storage.Storable;
import com.hortonworks.registries.storage.StorableKey;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * Default implementations go here
 */
public abstract class AbstractStorable implements Storable {
    private static final Logger LOG = LoggerFactory.getLogger(AbstractStorable.class);

    @JsonIgnore
    public StorableKey getStorableKey() {
        return new StorableKey(getNameSpace(), getPrimaryKey());
    }

    /**
     * Default implementation that will read all the instance variable names using API and
     * get the value by calling getter method (POJO) convention on it.
     * <p>
     * Sometimes for JDBC to work we need an extra layer of transformation , for example see the implementation
     * in {@code DataSource} which defines a field of type @{code Type} which is enum and not a primitive type as expected
     * by the JDBC layer, you can call this method and override the fields that needs transformation.
     *
     * @return
     */
    public Map<String, Object> toMap() {
        Set<String> instanceVariableNames = ReflectionHelper.getFieldNamesToTypes(this.getClass()).keySet();
        Map<String, Object> fieldToVal = new HashMap<>();
        for (String fieldName : instanceVariableNames) {
            try {
                Object val = ReflectionHelper.invokeGetter(fieldName, this);
                fieldToVal.put(fieldName, val);
                if (LOG.isTraceEnabled()) {
                    LOG.trace("toMap: Adding fieldName {} = {} ", fieldName, val);
                }
            } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {
                throw new StorageException(e);
            }
        }

        return fieldToVal;
    }

    /**
     * Default implementation that will read all the instance variable names and invoke setter.
     * <p>
     * Same as the toMap() method you should override this method when a field's defined type is not a primitive.
     *
     * @return
     */
    public Storable fromMap(Map<String, Object> map) {
        for (Map.Entry<String, Object> entry : map.entrySet()) {
            try {
                if (entry.getValue() != null) {
                    ReflectionHelper.invokeSetter(entry.getKey(), this, entry.getValue());
                }
            } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {
                throw new StorageException(e);
            }
        }
        return this;
    }

    /**
     * Default implementation that will generate schema by reading all the field names in the class and use its
     * define type to convert to the Schema type.
     *
     * @return
     */
    @JsonIgnore
    public Schema getSchema() {
        Map<String, Class> fieldNamesToTypes = ReflectionHelper.getFieldNamesToTypes(this.getClass());
        List<Schema.Field> fields = new ArrayList<>();

        for (Map.Entry<String, Class> entry : fieldNamesToTypes.entrySet()) {
            try {
                Object val = ReflectionHelper.invokeGetter(entry.getKey(), this);
                Schema.Type type;
                if (val != null) {
                    type = Schema.fromJavaType(val);
                } else {
                    type = Schema.fromJavaType(entry.getValue());
                }
                fields.add(new Schema.Field(entry.getKey(), type));
                if (LOG.isTraceEnabled()) {
                    LOG.trace("getSchema: Adding {} = {} ", entry.getKey(), type);
                }
            } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException | ParserException e) {
                throw new StorageException(e);
            }
        }

        return Schema.of(fields);
    }

    @Override
    public Long getId() {
        throw new UnsupportedOperationException("Not implemented");
    }

    @Override
    public void setId(Long id) {
        throw new UnsupportedOperationException("Not implemented");
    }

}