org.springframework.data.rest.webmvc.config.JsonPatchHandler.java Source code

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Here is the source code for org.springframework.data.rest.webmvc.config.JsonPatchHandler.java

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/*
 * Copyright 2014-2015 the original author or 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 org.springframework.data.rest.webmvc.config;

import java.io.InputStream;

import org.springframework.data.rest.webmvc.IncomingRequest;
import org.springframework.data.rest.webmvc.RestMediaTypes;
import org.springframework.data.rest.webmvc.json.DomainObjectReader;
import org.springframework.data.rest.webmvc.json.patch.JsonPatchPatchConverter;
import org.springframework.data.rest.webmvc.json.patch.Patch;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.util.Assert;

import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;

/**
 * Component to apply JSON Patch and JSON Merge Patch payloads to existing domain objects. The implementation uses the
 * JSON Patch library by Francis Galiegue but applies a customization to remove operations. As the patched node set
 * needs to be applied to the existing domain objects (see {@link DomainObjectReader} for that) we turn remove calls
 * into
 * 
 * @author Oliver Gierke
 * @see http://tools.ietf.org/html/rfc6902
 * @see http://tools.ietf.org/html/draft-ietf-appsawg-json-merge-patch-02
 */
class JsonPatchHandler {

    private final ObjectMapper mapper;
    private final ObjectMapper sourceMapper;
    private final DomainObjectReader reader;

    /**
     * Creates a new {@link JsonPatchHandler} with the given {@link ObjectMapper} and {@link DomainObjectReader}.
     * 
     * @param mapper must not be {@literal null}.
     * @param reader must not be {@literal null}.
     */
    public JsonPatchHandler(ObjectMapper mapper, DomainObjectReader reader) {

        Assert.notNull(mapper, "ObjectMapper must not be null!");
        Assert.notNull(reader, "DomainObjectReader must not be null!");

        this.mapper = mapper;
        this.reader = reader;

        this.sourceMapper = mapper.copy();
        this.sourceMapper.setSerializationInclusion(Include.NON_NULL);
    }

    /**
     * Applies the body of the given {@link IncomingRequest} as patch on the given target object.
     * 
     * @param request must not be {@literal null}.
     * @param target must not be {@literal null}.
     * @return
     * @throws Exception
     */
    public <T> T apply(IncomingRequest request, T target) throws Exception {

        Assert.notNull(request, "Request must not be null!");
        Assert.isTrue(request.isPatchRequest(), "Cannot handle non-PATCH request!");
        Assert.notNull(target, "Target must not be null!");

        if (request.isJsonPatchRequest()) {
            return applyPatch(request.getBody(), target);
        } else {
            return applyMergePatch(request.getBody(), target);
        }
    }

    <T> T applyPatch(InputStream source, T target) throws Exception {

        return getPatchOperations(source).apply(target, (Class<T>) target.getClass());
    }

    <T> T applyMergePatch(InputStream source, T existingObject) throws Exception {
        return reader.read(source, existingObject, mapper);
    }

    <T> T applyPut(ObjectNode source, T existingObject) {
        return reader.readPut(source, existingObject, mapper);
    }

    /**
     * Returns all {@link JsonPatchOperation}s to be applied.
     * 
     * @param source must not be {@literal null}.
     * @return
     * @throws HttpMessageNotReadableException in case the payload can't be read.
     */
    private Patch getPatchOperations(InputStream source) {

        try {
            return new JsonPatchPatchConverter().convert(mapper.readTree(source));
        } catch (Exception o_O) {
            throw new HttpMessageNotReadableException(
                    String.format("Could not read PATCH operations! Expected %s!", RestMediaTypes.JSON_PATCH_JSON),
                    o_O);
        }
    }
}