Python中的nifi executescript流文件创建问题

Question

我正在使用python脚本抓取页面（例如facebook页面），并希望传递要写入文件的每个帖子（类似于gettwitter进程）。 ExecuteScript是我的nifi数据流中的第一个处理器。 我设法使用session.create（）创建了流文件，但没有任何问题。

但是，我对如何将从Facebook读取的数据放入outputstreamCallback感到困惑。 我见过的大多数示例都使用Java重写，但是我必须使用Python，并且必须承认我对此并不陌生。

我在读取流文件时发现了很多示例，但没有太多内容。 以下是我想在Python中执行的Java操作。

FlowFile flowFile = session.create();
flowFile = session.write(flowFile, new OutputStreamCallback() {
    @Override
    public void process(final OutputStream out) throws IOException {
        out.write(tweet.getBytes(StandardCharsets.UTF_8));

如果还有其他方法，请指导。 谢谢。

---

在采用@James建议的更改之后，我编写了一个片段，如下所示，但未传输流文件。 虽然没有编译错误。

import urllib2
import json
import datetime
import csv
import time
import sys
import traceback
from org.apache.nifi.processor.io import OutputStreamCallback
from org.python.core.util import StringUtil

class WriteContentCallback(OutputStreamCallback):
    def __init__(self, content):
        self.content_text = content

    def process(self, outputStream):
        try:
            outputStream.write(StringUtil.toBytes(self.content_text))
        except:
            traceback.print_exc(file=sys.stdout)
            raise

#app_id = "<FILL IN>"
#app_secret = "<FILL IN>" # DO NOT SHARE WITH ANYONE!
page_id = "dsssssss"
#page_id = raw_input("Please Paste Public Page Name:")

#access_token = app_id + "|" + app_secret

access_token = "sdfsdfsf%sdfsdf"

#access_token = raw_input("Please Paste Your Access Token:")


def scrapeFacebookPageFeedStatus(page_id, access_token):
        flowFile = session.create()
        flowFile = session.write(flowFile, WriteContentCallback("Hello there this is my data"))
        flowFile = session.write()
        session.transfer(flowFile, REL_SUCCESS)

        has_next_page = False
        num_processed = 0   # keep a count on how many we've processed
        scrape_starttime = datetime.datetime.now()


        while has_next_page:
            print "Scraping %s Facebook Page: %s\n" % (page_id, scrape_starttime)
            has_next_page = False

        print "\nDone!\n%s Statuses Processed in %s" % \
                (num_processed, datetime.datetime.now() - scrape_starttime)


if __name__ == '__main__':
    scrapeFacebookPageFeedStatus(page_id, access_token)
    flowFile = session.create()
    flowFile = session.write(flowFile, WriteContentCallback("and your data"))
    session.transfer(flowFile, REL_SUCCESS)

以下是nifi-app.log的输出

> [root@ambari logs]# tail -100 nifi-app.log 2017-04-03 14:08:07,989
> INFO [StandardProcessScheduler Thread-6]
> o.a.n.c.s.TimerDrivenSchedulingAgent Scheduled
> ExecuteScript[id=a62f4b97-8fd7-15cd-95b9-505e1b960805] to run with 1
> threads 2017-04-03 14:08:08,938 INFO [Flow Service Tasks Thread-2]
> o.a.nifi.controller.StandardFlowService Saved flow controller
> org.apache.nifi.controller.FlowController@44ec5960 // Another save
> pending = false 2017-04-03 14:08:13,789 INFO [StandardProcessScheduler
> Thread-3] o.a.n.c.s.TimerDrivenSchedulingAgent Scheduled
> PutFile[id=a62f4b8e-8fd7-15cd-7517-56593deabf55] to run with 1 threads
> 2017-04-03 14:08:14,296 INFO [Flow Service Tasks Thread-2]
> o.a.nifi.controller.StandardFlowService Saved flow controller
> org.apache.nifi.controller.FlowController@44ec5960 // Another save
> pending = false

Answer 1

这是Python ExecuteScript中NiFi OutputStreamCallback的简单实现：

import sys
import traceback
from org.apache.nifi.processor.io import OutputStreamCallback
from org.python.core.util import StringUtil

class WriteContentCallback(OutputStreamCallback):
    def __init__(self, content):
        self.content_text = content

    def process(self, outputStream):
        try:
            outputStream.write(StringUtil.toBytes(self.content_text))
        except:
            traceback.print_exc(file=sys.stdout)
            raise

# Create new FlowFile with content
flowFile = session.create()
flowFile = session.write(flowFile, WriteContentCallback("This is the flowfile content"))
session.transfer(flowFile, REL_SUCCESS)