001/*
002 * Copyright 2002-2019 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.ui;
018
019import java.util.Collection;
020import java.util.Map;
021
022import org.springframework.lang.Nullable;
023
024/**
025 * Java-5-specific interface that defines a holder for model attributes.
026 * Primarily designed for adding attributes to the model.
027 * Allows for accessing the overall model as a {@code java.util.Map}.
028 *
029 * @author Juergen Hoeller
030 * @since 2.5.1
031 */
032public interface Model {
033
034        /**
035         * Add the supplied attribute under the supplied name.
036         * @param attributeName the name of the model attribute (never {@code null})
037         * @param attributeValue the model attribute value (can be {@code null})
038         */
039        Model addAttribute(String attributeName, @Nullable Object attributeValue);
040
041        /**
042         * Add the supplied attribute to this {@code Map} using a
043         * {@link org.springframework.core.Conventions#getVariableName generated name}.
044         * <p><i>Note: Empty {@link java.util.Collection Collections} are not added to
045         * the model when using this method because we cannot correctly determine
046         * the true convention name. View code should check for {@code null} rather
047         * than for empty collections as is already done by JSTL tags.</i>
048         * @param attributeValue the model attribute value (never {@code null})
049         */
050        Model addAttribute(Object attributeValue);
051
052        /**
053         * Copy all attributes in the supplied {@code Collection} into this
054         * {@code Map}, using attribute name generation for each element.
055         * @see #addAttribute(Object)
056         */
057        Model addAllAttributes(Collection<?> attributeValues);
058
059        /**
060         * Copy all attributes in the supplied {@code Map} into this {@code Map}.
061         * @see #addAttribute(String, Object)
062         */
063        Model addAllAttributes(Map<String, ?> attributes);
064
065        /**
066         * Copy all attributes in the supplied {@code Map} into this {@code Map},
067         * with existing objects of the same name taking precedence (i.e. not getting
068         * replaced).
069         */
070        Model mergeAttributes(Map<String, ?> attributes);
071
072        /**
073         * Does this model contain an attribute of the given name?
074         * @param attributeName the name of the model attribute (never {@code null})
075         * @return whether this model contains a corresponding attribute
076         */
077        boolean containsAttribute(String attributeName);
078
079        /**
080         * Return the attribute value for the given name, if any.
081         * @param attributeName the name of the model attribute (never {@code null})
082         * @return the corresponding attribute value, or {@code null} if none
083         * @since 5.2
084         */
085        @Nullable
086        Object getAttribute(String attributeName);
087
088        /**
089         * Return the current set of model attributes as a Map.
090         */
091        Map<String, Object> asMap();
092
093}