com.cloudera.csd.validation.references.constraints.AbstractReferenceConstraint.java Source code

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Here is the source code for com.cloudera.csd.validation.references.constraints.AbstractReferenceConstraint.java

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// Licensed to Cloudera, Inc. under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  Cloudera, Inc. licenses this file
// to you 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.cloudera.csd.validation.references.constraints;

import com.cloudera.csd.validation.references.ReferenceConstraint;
import com.google.common.base.Predicate;
import com.google.common.collect.Collections2;
import com.google.common.collect.ImmutableList;

import java.lang.reflect.Method;
import java.util.Collection;
import java.util.Map;

import javax.annotation.Nullable;

import org.springframework.util.ReflectionUtils;

/**
 * Provides common common functionality for
 * all reference constraints.
 *
 * @param <T> the root object type.
 */
public abstract class AbstractReferenceConstraint<T> implements ReferenceConstraint<T> {

    /**
     * Normalizes the results of invoking the method on the object.
     * If the method returns a single string, it is wrapped in a list.
     * If the result is a map, the values of the map are used to create
     * the collection of strings.
     * @param method the method to invoke
     * @param obj the object to invoke the method on.
     * @return the list of returned ids. Nulls are filtered out.
     */
    protected Collection<String> getIds(Method method, Object obj) {
        Object result = ReflectionUtils.invokeMethod(method, obj);
        Collection<String> ids;
        if (result instanceof Collection) {
            ids = (Collection<String>) result;
        } else if (result instanceof Map) {
            ids = ((Map<?, String>) result).values();
        } else {
            ids = ImmutableList.of((String) result);
        }
        return Collections2.filter(ids, new Predicate<String>() {
            public boolean apply(@Nullable String input) {
                return (input != null);
            }
        });
    }
}