flink-runtime/src/main/java/org/apache/flink/runtime/rest/handler/util/HandlerRequestUtils.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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 org.apache.flink.runtime.rest.handler.util;

import org.apache.flink.runtime.rest.handler.HandlerRequest;
import org.apache.flink.runtime.rest.handler.RestHandlerException;
import org.apache.flink.runtime.rest.messages.MessageParameters;
import org.apache.flink.runtime.rest.messages.MessageQueryParameter;
import org.apache.flink.runtime.rest.messages.RequestBody;
import org.apache.flink.util.function.SupplierWithException;

import org.apache.flink.shaded.netty4.io.netty.handler.codec.http.HttpResponseStatus;

import org.slf4j.Logger;

import java.util.List;

/** Utils for getting query parameters from {@link HandlerRequest}. */
public class HandlerRequestUtils {

    /**
     * Returns the value of a query parameter, or {@code null} if the query parameter is not set.
     *
     * @throws RestHandlerException If the query parameter is repeated.
     */
    public static <
                    X,
                    P extends MessageQueryParameter<X>,
                    R extends RequestBody,
                    M extends MessageParameters>
            X getQueryParameter(final HandlerRequest<R> request, final Class<P> queryParameterClass)
                    throws RestHandlerException {

        return getQueryParameter(request, queryParameterClass, null);
    }

    public static <
                    X,
                    P extends MessageQueryParameter<X>,
                    R extends RequestBody,
                    M extends MessageParameters>
            X getQueryParameter(
                    final HandlerRequest<R> request,
                    final Class<P> queryParameterClass,
                    final X defaultValue)
                    throws RestHandlerException {

        final List<X> values = request.getQueryParameter(queryParameterClass);
        final X value;
        if (values.size() > 1) {
            throw new RestHandlerException(
                    String.format("Expected only one value %s.", values),
                    HttpResponseStatus.BAD_REQUEST);
        } else if (values.size() == 1) {
            value = values.get(0);
        } else {
            value = defaultValue;
        }
        return value;
    }

    /**
     * Returns {@code requestValue} if it is not null, otherwise returns the query parameter value
     * if it is not null, otherwise returns the default value.
     */
    public static <T> T fromRequestBodyOrQueryParameter(
            T requestValue,
            SupplierWithException<T, RestHandlerException> queryParameterExtractor,
            T defaultValue,
            Logger log)
            throws RestHandlerException {
        if (requestValue != null) {
            return requestValue;
        } else {
            T queryParameterValue = queryParameterExtractor.get();
            if (queryParameterValue != null) {
                log.warn(
                        "Configuring the job submission via query parameters is deprecated."
                                + " Please migrate to submitting a JSON request instead.");
                return queryParameterValue;
            } else {
                return defaultValue;
            }
        }
    }
}