io.wcm.caravan.pipeline.impl.operators.AssertExistsOperator.java Source code

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Here is the source code for io.wcm.caravan.pipeline.impl.operators.AssertExistsOperator.java

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/*
 * #%L
 * wcm.io
 * %%
 * Copyright (C) 2014 wcm.io
 * %%
 * 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.
 * #L%
 */
package io.wcm.caravan.pipeline.impl.operators;

import io.wcm.caravan.pipeline.JsonPipelineInputException;
import io.wcm.caravan.pipeline.JsonPipelineOutput;
import io.wcm.caravan.pipeline.impl.JsonPathSelector;
import rx.Observable.Operator;
import rx.Subscriber;
import rx.exceptions.Exceptions;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.jayway.jsonpath.JsonPath;
import com.jayway.jsonpath.PathNotFoundException;

/**
 * An operator that will check if the pipeline's output contains data at a given JSONPath, and fail with a
 * {@link JsonPipelineInputException} if this assumptions is not fulfilled.
 */
public class AssertExistsOperator implements Operator<JsonPipelineOutput, JsonPipelineOutput> {

    private final String jsonPath;
    private final int statusCode;
    private final String msg;

    /**
     * @param jsonPath the JSONPath to evaluate on the pipeline's output
     * @param statusCode the appropriate HTTP status code in case data is missing
     * @param msg an informative error message
     */
    public AssertExistsOperator(String jsonPath, int statusCode, String msg) {

        // fail fast if the given json path is invalid
        JsonPath.compile(jsonPath);

        this.jsonPath = jsonPath;
        this.statusCode = statusCode;
        this.msg = msg;
    }

    @Override
    public Subscriber<? super JsonPipelineOutput> call(Subscriber<? super JsonPipelineOutput> subscriber) {
        return new Subscriber<JsonPipelineOutput>() {

            private boolean assertionFailed;

            @Override
            public void onCompleted() {
                // take care not to call #onCompleted if #onError has been called because the assertion failed
                if (!assertionFailed) {
                    subscriber.onCompleted();
                }
            }

            @Override
            public void onError(Throwable e) {
                Exceptions.throwIfFatal(e);
                subscriber.onError(e);
            }

            @Override
            public void onNext(JsonPipelineOutput output) {

                JsonNode jsonResponse = output.getPayload();

                // if this #assertExist is chained after an #extract call, the responseNode or its child node can be a MissingNode and we should bail out early

                if (jsonResponse == null || jsonResponse.isMissingNode() || !jsonResponse.iterator().hasNext()
                        || (jsonResponse.isObject() && jsonResponse.iterator().next().isMissingNode())) {
                    onAssertionFailed();
                    return;
                }

                try {
                    // evalute the JSONPath on the pipeline's response
                    ArrayNode jsonPathResult = new JsonPathSelector(jsonPath).call(jsonResponse);

                    if (jsonPathResult.size() == 0) {
                        onAssertionFailed();
                    } else {
                        // the responseNode has content at the given JsonPath, so we can continue processing the response
                        subscriber.onNext(output);
                    }
                } catch (PathNotFoundException p) {
                    onAssertionFailed();
                }
            }

            public void onAssertionFailed() {
                assertionFailed = true;
                this.onError(new JsonPipelineInputException(statusCode, msg));
            }
        };
    }
}