QueryMap.java

/*
 * Copyright 2012-2023 The Feign Authors
 *
 * 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 feign;

import java.lang.annotation.Retention;
import java.util.List;
import java.util.Map;
import feign.querymap.BeanQueryMapEncoder;
import feign.querymap.FieldQueryMapEncoder;
import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

/**
 * A template parameter that can be applied to a Map that contains query parameters, where the keys
 * are Strings that are the parameter names and the values are the parameter values. The queries
 * specified by the map will be applied to the request after all other processing, and will take
 * precedence over any previously specified query parameters. It is not necessary to reference the
 * parameter map as a variable. <br>
 * <br>
 * 
 * <pre>
 * ...
 * &#64;RequestLine("POST /servers")
 * void servers(&#64;QueryMap Map<String, String>);
 * ...
 *
 * &#64;RequestLine("GET /servers/{serverId}?count={count}")
 * void get(&#64;Param("serverId") String serverId, &#64;Param("count") int count, &#64;QueryMap Map<String, Object>);
 * ...
 * </pre>
 * 
 * The annotated parameter must be an instance of {@link Map}, and the keys must be Strings. The
 * query value of a key will be the value of its toString method, except in the following cases:
 * <br>
 * <br>
 * <ul>
 * <li>if the value is null, the value will remain null (rather than converting to the String
 * "null")
 * <li>if the value is an {@link Iterable}, it is converted to a {@link List} of String objects
 * where each value in the list is either null if the original value was null or the value's
 * toString representation otherwise.
 * </ul>
 * <br>
 * Once this conversion is applied, the query keys and resulting String values follow the same
 * contract as if they were set using {@link RequestTemplate#query(String, String...)}.
 */
@Retention(RUNTIME)
@java.lang.annotation.Target(PARAMETER)
public @interface QueryMap {

  /**
   * Specifies whether parameter names and values are already encoded.
   * <p>
   * Deprecation: there are two options
   * <ul>
   * <li>if name or value are already encoded we do nothing;</li>
   * <li>if name or value are not encoded we encode them.</li>
   * </ul>
   *
   * @see Param#encoded
   * @deprecated
   */
  boolean encoded() default false;

  /**
   * Specifies the QueryMapEncoder implementation to use to transform DTO into query map.
   * 
   * @return the enum containing the instance of QueryMapEncoder
   */
  MapEncoder mapEncoder() default MapEncoder.DEFAULT;

  public enum MapEncoder {
    // the latter DEFAULT will use BaseBuilder instance
    BEAN(new BeanQueryMapEncoder()), FIELD(new FieldQueryMapEncoder()), DEFAULT(null);

    private QueryMapEncoder mapEncoder;

    private MapEncoder(QueryMapEncoder mapEncoder) {
      this.mapEncoder = mapEncoder;
    }

    public QueryMapEncoder instance() {
      return mapEncoder;
    }
  }
}