io.wcm.caravan.pipeline.extensions.hal.filter.HalResourceFilters.java Source code

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Here is the source code for io.wcm.caravan.pipeline.extensions.hal.filter.HalResourceFilters.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.
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package io.wcm.caravan.pipeline.extensions.hal.filter;

import java.util.List;
import java.util.stream.Stream;

import org.apache.commons.lang3.StringUtils;
import org.osgi.annotation.versioning.ProviderType;

import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.jayway.jsonpath.Configuration;
import com.jayway.jsonpath.JsonPath;
import com.jayway.jsonpath.Option;

import io.wcm.caravan.hal.resource.HalResource;
import rx.functions.Func1;

/**
 * Default filtering predicates for HAL resources.
 */
@ProviderType
public final class HalResourceFilters {

    private static final Configuration JSON_PATH_CONF = Configuration.defaultConfiguration()
            .addOptions(Option.ALWAYS_RETURN_LIST, Option.SUPPRESS_EXCEPTIONS);

    /** JSON object mapper */
    private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper()
            .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);

    private HalResourceFilters() {
        // nothing to do
    }

    /**
     * Executes all predicates and combines the result by logical {@code and}. If there are negative predicate results,
     * remaining predicates will not get executed.
     * @param predicates Predicates to check
     * @return True if all predicates return true
     */
    public static HalResourcePredicate all(HalResourcePredicate... predicates) {
        return new HalResourcePredicate() {

            @Override
            public boolean apply(HalPath halPath, HalResource hal) {

                for (HalResourcePredicate predicate : predicates) {
                    if (!predicate.apply(halPath, hal)) {
                        return false;
                    }
                }
                return true;

            }

            @Override
            public String getId() {
                List<String> ids = Stream.of(predicates).map(matcher -> matcher.getId())
                        .collect(java.util.stream.Collectors.toList());

                return "ALL(" + StringUtils.join(ids, '+') + ")";
            }
        };
    }

    /**
     * @param jsonPath JSON path to check
     * @return True if model has field(s) for given JSON path and all values are not null
     */
    public static HalResourcePredicate hasPathNonNull(String jsonPath) {
        JsonPath compiledPath = JsonPath.compile(jsonPath);
        return new HalResourcePredicate() {

            @Override
            public String getId() {
                return "HAS(" + jsonPath + ")";
            }

            @Override
            public boolean apply(HalPath halPath, HalResource hal) {
                ObjectNode json = hal.getModel();
                ArrayNode matches = compiledPath.read(json, JSON_PATH_CONF);
                // check for empty result list
                if (matches == null || matches.size() == 0) {
                    return false;
                }
                // check for null value
                for (JsonNode match : matches) {
                    if (match == null || match.isNull()) {
                        return false;
                    }
                }
                return true;
            }

        };
    }

    /**
     * @param fieldName JSON field name
     * @return True if field exists and is not null
     */
    public static HalResourcePredicate hasNonNull(String fieldName) {
        return new HalResourcePredicate() {

            @Override
            public String getId() {
                return "HAS(" + fieldName + ")";
            }

            @Override
            public boolean apply(HalPath halPath, HalResource hal) {
                return hal.getModel().hasNonNull(fieldName);
            }

        };
    }

    /**
     * @param relation Relation name of the embedded resource
     * @return True if HAL resource has one or more embedded resources for the given relation name
     */
    public static HalResourcePredicate hasEmbedded(String relation) {
        return new HalResourcePredicate() {

            @Override
            public String getId() {
                return "HAS-EMBEDDED(" + relation + ")";
            }

            @Override
            public boolean apply(HalPath halPath, HalResource hal) {
                return hal.hasEmbedded(relation) && !hal.getEmbedded(relation).isEmpty();
            }

        };
    }

    /**
     * Converts the state of the HAL resource to an object of the given type and applies the provided function.
     * @param <S> Type of the HAL resource state
     * @param clazz Class type of the HAL resource state
     * @param function Function to apply on the object
     * @return Return value of the executed function
     */
    public static <S> HalResourcePredicate object(Class<S> clazz, Func1<S, Boolean> function) {
        return new HalResourcePredicate() {

            @Override
            public String getId() {
                return "OBJECT(" + clazz.getSimpleName() + ")";
            }

            @Override
            public boolean apply(HalPath halPath, HalResource hal) {
                S object = OBJECT_MAPPER.convertValue(hal.getModel(), clazz);
                return function.call(object);
            }

        };

    }

}