Support extraction of Fields from JSON data source

[hemanthkilari]

Support for extraction of Fields from JSON data source in Ranger can make it powerful in streamlining data across the Requests mentioned in Berserker configuration. I have already Implemented support for it. Attached the Implementation. Please provide your comments.

[hemanthkilari]

package io.smartcat.ranger.core;

import java.io.FileInputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.jayway.jsonpath.JsonPath;

/**

• @author hkilari

•     UserDefined Value Implementation to allow Berserker User define a Custom Value in
  

•     berserker ranger configuration. The Custom Value will be retrieved from the data source
  

•     configured by User based on his query config
  

*/
public class UserDefinedValue extends Value {

private Value<String> jsonName;
private Value<String> filter;
private Value<String> regExpression;
private List<String> finalContent;
private long contentlastUpdationTime;
private Value<String> refreshInterval;
private Value<String> defaultRefreshInterval = new Value<String>() {
};

public UserDefinedValue(Value<String> regExpression, Value<String> refreshInterval, Value<String> filter,
        Value<String> jsonName) {
    defaultRefreshInterval.val = "600";
    if (jsonName == null) {
        throw new IllegalArgumentException("datasource cannot be null.");
    }
    this.jsonName = jsonName;
    this.filter = filter;
    this.regExpression = regExpression;
    this.refreshInterval = refreshInterval == null ? defaultRefreshInterval : refreshInterval;
    this.finalContent = new ArrayList<>();
}

@Override
public void reset() {
    jsonName.reset();
    filter.reset();
    regExpression.reset();
    refreshInterval.reset();
    super.reset();

}

@Override
protected void eval() {
    if (isContentExpired()) {
        getDataFromJson();
    }
    val = getRandomValue();
}

private boolean isContentExpired() {
    //Checks if the finalContent to be  refreshed based on used defined refreshInterval.
    if (System.currentTimeMillis() - contentlastUpdationTime > Long.parseLong(refreshInterval.val) * 1000) {
        return true;
    }
    return false;
}

private String getRandomValue() {
    if (finalContent != null && !finalContent.isEmpty())
        return extractFiled(finalContent.get(new Random().nextInt(finalContent.size())).toString(),
                regExpression.get());
    else
        return "";
}

private void getDataFromJson() {
    try {
        //check If Source is a http service
        if (jsonName.get().contains("http")) {
            getDataFromHttpRequest();
        } else {
            //Source treated as a local json file
            InputStream in =
                    Thread.currentThread().getContextClassLoader().getResourceAsStream(jsonName.get() + ".json");
            if (in == null) {
                in = new FileInputStream(jsonName.get() + ".json");
            }
            if (in != null) {
                finalContent = JsonPath.read(in, filter.get());
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

/**
 * Retrieves data from a http servcie endpoint
 */
private void getDataFromHttpRequest() {
    try {
        InputStream in;
        URL obj = new URL(jsonName.val);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();
        con.setRequestMethod("GET");
        con.setRequestProperty("accept", "application/json");
        int responseCode = con.getResponseCode();
        if (responseCode == HttpURLConnection.HTTP_OK) { // success
            in = con.getInputStream();
            finalContent = JsonPath.read(in, filter.get());
            in.close();
            contentlastUpdationTime = System.currentTimeMillis();
        } else {
            System.out.println("GET request not worked");
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

/**
 * @param latestCommandOutput
 * @param regExpression
 * @return
 */
private String extractFiled(String inputString, String regExpression) {
    if (regExpression != null && !"".equals(regExpression.trim())) {
        Pattern p = Pattern.compile(regExpression);
        Matcher m = p.matcher(inputString);
        if (m.find()) {
            if (m.groupCount() > 0)
                return m.group(1);
        }
        return null;
    }
    return inputString;
}

}

[vajda]

Thanks for your effort. But it is fairly hard to read code from the comment. Can you please branch from dev and create a pull request?