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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-1661) Implement built-in functions for JSON
Date Sun, 28 Jun 2015 17:59:04 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-1661?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14604807#comment-14604807
] 

ASF GitHub Bot commented on PHOENIX-1661:
-----------------------------------------

Github user AakashPradeep commented on a diff in the pull request:

    https://github.com/apache/phoenix/pull/93#discussion_r33425135
  
    --- Diff: phoenix-core/src/main/java/org/apache/phoenix/schema/json/PhoenixJson.java ---
    @@ -0,0 +1,355 @@
    +/*
    + * Licensed to the Apache Software Foundation (ASF) under one
    + * or more contributor license agreements.  See the NOTICE file
    + * distributed with this work for additional information
    + * regarding copyright ownership.  The ASF licenses this file
    + * to you 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.apache.phoenix.schema.json;
    +
    +import java.io.IOException;
    +import java.sql.SQLException;
    +import java.util.Arrays;
    +import java.util.ArrayList;
    +import java.util.Iterator;
    +import java.util.List;
    +import java.util.Map;
    +
    +import org.apache.hadoop.hbase.util.Bytes;
    +import org.apache.phoenix.exception.SQLExceptionCode;
    +import org.apache.phoenix.exception.SQLExceptionInfo;
    +import org.apache.phoenix.schema.EqualityNotSupportedException;
    +import org.apache.phoenix.schema.types.*;
    +import org.codehaus.jackson.JsonFactory;
    +import org.codehaus.jackson.JsonNode;
    +import org.codehaus.jackson.JsonParser;
    +import org.codehaus.jackson.JsonParser.Feature;
    +import org.codehaus.jackson.JsonProcessingException;
    +import org.codehaus.jackson.map.ObjectMapper;
    +import org.codehaus.jackson.node.ValueNode;
    +
    +import com.google.common.base.Preconditions;
    +
    +/**
    + * The {@link PhoenixJson} wraps json and uses Jackson library to parse and traverse
the json. It
    + * should be used to represent the JSON data type and also should be used to parse Json
data and
    + * read the value from it. It always conside the last value if same key exist more than
once.
    + */
    +public class PhoenixJson implements Comparable<PhoenixJson> {
    +    private final JsonNode rootNode;
    +    /*
    +     * input data has been stored as it is, since some data is lost when json parser
runs, for
    +     * example if a JSON object within the value contains the same key more than once
then only last
    +     * one is stored rest all of them are ignored, which will defy the contract of PJsonDataType
of
    +     * keeping user data as it is.
    +     */
    +    private final String jsonAsString;
    +
    +    /**
    +     * Static Factory method to get an {@link PhoenixJson} object. It also validates
the json and
    +     * throws {@link SQLException} if it is invalid with line number and character.
    +     * @param jsonData Json data as {@link String}.
    +     * @return {@link PhoenixJson}.
    +     * @throws SQLException
    +     */
    +    public static PhoenixJson getInstance(String jsonData) throws SQLException {
    +        if (jsonData == null) {
    +           return null;
    +        }
    +        try {
    +            JsonFactory jsonFactory = new JsonFactory();
    +            JsonParser jsonParser = jsonFactory.createJsonParser(jsonData);
    +            JsonNode jsonNode = getRootJsonNode(jsonParser);
    +            return new PhoenixJson(jsonNode, jsonData);
    +        } catch (IOException x) {
    +            throw new SQLExceptionInfo.Builder(SQLExceptionCode.INVALID_JSON_DATA).setRootCause(x)
    +                    .setMessage(x.getMessage()).build().buildException();
    +        }
    +
    +    }
    +
    +    /**
    +     * Returns the root of the resulting {@link JsonNode} tree.
    +     */
    +    private static JsonNode getRootJsonNode(JsonParser jsonParser) throws IOException,
    +            JsonProcessingException {
    +        jsonParser.configure(Feature.ALLOW_COMMENTS, true);
    +        ObjectMapper objectMapper = new ObjectMapper();
    +        try {
    +            return objectMapper.readTree(jsonParser);
    +        } finally {
    +            jsonParser.close();
    +        }
    +    }
    +
    +    /* Default for unit testing */PhoenixJson(final JsonNode node, final String jsonData)
{
    +        Preconditions.checkNotNull(node, "root node cannot be null for json");
    +        this.rootNode = node;
    +        this.jsonAsString = jsonData;
    +    }
    +
    +    /**
    +     * Get {@link PhoenixJson} for a given json paths. For example :
    +     * <p>
    +     * <code>
    +     * {"f2":{"f3":1},"f4":{"f5":99,"f6":{"f7":"2"}}}'
    +     * </code>
    +     * <p>
    +     * for this source json, if we want to know the json at path {'f4','f6'} it will
return
    +     * {@link PhoenixJson} object for json {"f7":"2"}. It always returns the last key
if same key
    +     * exist more than once.
    +     * <p>
    +     * If the given path is unreachable then it throws {@link SQLException}.
    +     * @param paths {@link String []} of path in the same order as they appear in json.
    +     * @return {@link PhoenixJson} for the json against @paths.
    +     * @throws SQLException
    +     */
    +    public PhoenixJson getPhoenixJson(String[] paths) throws SQLException {
    +        try {
    +            PhoenixJson phoenixJson = getPhoenixJsonInternal(paths);
    +            if (phoenixJson == null) {
    +                throw new SQLException("path: " + Arrays.asList(paths) + " not found.");
    +            }
    +            return phoenixJson;
    +        } catch (NumberFormatException nfe) {
    +            throw new SQLException("path: " + Arrays.asList(paths) + " not found.", nfe);
    +        }
    +    }
    +
    +    /**
    +     * Get {@link PhoenixJson} for a given json paths. For example :
    +     * <p>
    +     * <code>
    +     * {"f2":{"f3":1},"f4":{"f5":99,"f6":{"f7":"2"}}}'
    +     * </code>
    +     * <p>
    +     * for this source json, if we want to know the json at path {'f4','f6'} it will
return
    +     * {@link PhoenixJson} object for json {"f7":"2"}. It always returns the last key
if same key
    +     * exist more than once.
    +     * <p>
    +     * If the given path is unreachable then it return null.
    +     * @param paths {@link String []} of path in the same order as they appear in json.
    +     * @return {@link PhoenixJson} for the json against @paths.
    +     */
    +    public PhoenixJson getPhoenixJsonOrNull(String[] paths) {
    +        try {
    +            return getPhoenixJsonInternal(paths);
    +        } catch (NumberFormatException nfe) {
    +            // ignore
    +        }
    +        return null;
    +    }
    +
    +    /**
    +     * Serialize the current {@link PhoenixJson} to String. Its required for
    +     * json_extract_path_text(). If we just return node.toString() it will wrap String
value in
    +     * double quote which is not the expectation, hence avoiding calling toString() on
    +     * {@link JsonNode} until PhoenixJson represent a Json Array or container for Json
object. If
    +     * PhoenixJson just represent a {@link ValueNode} then it should return value returned
from
    +     * objects toString().
    +     */
    +    public String serializeToString() {
    +        if (this.rootNode == null || this.rootNode.isNull()) {
    +            return null;
    +        } else if (this.rootNode.isValueNode()) {
    +
    +            if (this.rootNode.isNumber()) {
    +                return this.rootNode.getNumberValue().toString();
    +            } else if (this.rootNode.isBoolean()) {
    +                return String.valueOf(this.rootNode.getBooleanValue());
    +            } else if (this.rootNode.isTextual()) {
    +                return this.rootNode.getTextValue();
    +            } else {
    +                return this.jsonAsString;
    +            }
    +        } else if (this.rootNode.isArray()) {
    +            return this.jsonAsString;
    +        } else if (this.rootNode.isContainerNode()) {
    +            return this.jsonAsString;
    +        }
    +
    +        return null;
    +
    +    }
    +
    +    @Override
    +    public String toString() {
    +        return this.jsonAsString;
    +    }
    +
    +    @Override
    +    public int hashCode() {
    +        final int prime = 31;
    +        int result = 1;
    +        result = prime * result + this.jsonAsString.hashCode();
    +        return result;
    +    }
    +
    +    @Override
    +    public boolean equals(Object obj) {
    +        throw new EqualityNotSupportedException(PJson.INSTANCE);
    +    }
    +
    +    /**
    +     * @return length of the string represented by the current {@link PhoenixJson}.
    +     */
    +    public int estimateByteSize() {
    +        String jsonStr = toString();
    +        return jsonStr == null ? 1 : jsonStr.length();
    +    }
    +
    +    public byte[] toBytes() {
    +        return Bytes.toBytes(this.jsonAsString);
    +    }
    +
    +    @Override
    +    public int compareTo(PhoenixJson o) {
    +        throw new EqualityNotSupportedException(PJson.INSTANCE);
    +    }
    +
    +    private PhoenixJson getPhoenixJsonInternal(String[] paths) {
    +        JsonNode node = this.rootNode;
    +        for (String path : paths) {
    +            JsonNode nodeTemp = null;
    +            if (node.isArray()) {
    +                int index = Integer.parseInt(path);
    +                nodeTemp = node.path(index);
    +            } else {
    +                nodeTemp = node.path(path);
    +            }
    +            if (nodeTemp == null || nodeTemp.isMissingNode()) {
    +                return null;
    +            }
    +            node = nodeTemp;
    +        }
    +        return new PhoenixJson(node, node.toString());
    +    }
    +
    +    public int getJsonArrayLength() {
    +        int count = 0;
    +        Iterator<JsonNode> elements = this.rootNode.getElements();
    +        while(elements.hasNext()){
    +            elements.next();
    +            count++;
    +        }
    +        return count;
    +    }
    +
    +    public Object[] getJsonArrayElements() {
    +        List<String> elementlist = new ArrayList();
    +        Iterator<JsonNode> elements = this.rootNode.getElements();
    +        while(elements.hasNext()){
    +            JsonNode e = elements.next();
    +            elementlist.add(e.toString());
    +        }
    +        return elementlist.toArray();
    +    }
    +
    +    public Object[] getJsonObjectKeys() {
    +        List<String> elementlist = new ArrayList();
    +        Iterator<String> fieldnames = this.rootNode.getFieldNames();
    +        while(fieldnames.hasNext()){
    +            elementlist.add(fieldnames.next());
    +        }
    +        return elementlist.toArray();
    +    }
    +
    +    public Object[] getJsonFields() {
    +        List<String> elementlist = new ArrayList();
    +        Iterator<Map.Entry<String, JsonNode>> fields = this.rootNode.getFields();
    +
    +        while(fields.hasNext()){
    +            String fieldsstr = "";
    +            Map.Entry<String, JsonNode> entry = fields.next();
    +            fieldsstr += entry.getKey() +","+entry.getValue().toString();
    --- End diff --
    
    Please specify why you are using "," as a separator b/w key and value.


> Implement built-in functions for JSON
> -------------------------------------
>
>                 Key: PHOENIX-1661
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-1661
>             Project: Phoenix
>          Issue Type: Bug
>            Reporter: James Taylor
>              Labels: JSON, Java, SQL, gsoc2015, mentor
>         Attachments: PhoenixJSONSpecification-First-Draft.pdf
>
>
> Take a look at the JSON built-in functions that are implemented in Postgres (http://www.postgresql.org/docs/9.3/static/functions-json.html)
and implement the same for Phoenix in Java following this guide: http://phoenix-hbase.blogspot.com/2013/04/how-to-add-your-own-built-in-function.html
> Examples of functions include ARRAY_TO_JSON, ROW_TO_JSON, TO_JSON, etc. The implementation
of these built-in functions will be impacted by how JSON is stored in Phoenix. See PHOENIX-628.
An initial implementation could work off of a simple text-based JSON representation and then
when a native JSON type is implemented, they could be reworked to be more efficient.



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