从 kafka 主题打印 Pyspark 流数据

Question

I am new to kafka and pyspark and trying to write simple program, SO I have 2 files in kafka Topics in JSon format and I am reading this from pyspark streaming.

My Producer code is as follows:

  from kafka import *
import json
import time
import boto3
import json
from Consumer_Group import *
from json import loads
class producer :
            def json_serializer(data):
                    return json.dumps(data).encode("utf-8")

            def read_s3():
                p1 = KafkaProducer(bootstrap_servers=['localhost:9092'], value_serializer=producer.json_serializer)
                s3 = boto3.resource('s3')
                bucket = s3.Bucket('kakfa')
                for obj in bucket.objects.all():
                    key = obj.key
                    body = obj.get()['Body'].read().decode('utf-8')
                p1.send("Uber_Eats",body)
                p1.flush()

My Consumer code is as follows:

from pyspark.sql import SparkSession
from kafka import *
import time
class consumer:
                def read_from_topic(self,spark):
                        df = spark.readStream \
                            .format("kafka") \
                            .option("kafka.bootstrap.servers", "localhost:9092") \
                            .option("subscribe", "Uber_Eats") \
                             .option("startingOffsets", "earliest") \
                            .load()
                        df.createOrReplaceTempView("kafka")
                        spark.sql("select * from kafka")
                        print(df.isStreaming())
                                  


                def get_consumer(self):
                    consumer = KafkaConsumer("Uber_Eats", group_id='group1', bootstrap_servers=
                    "localhost:9092")
                    return  consumer

                def print_details(self,c1):
                    #    self.consumer=self.get_consumer(self)
                        # Read and print message from consumer
                     try:
                                for msg in c1:
                                    print(msg.topic, msg.value)
                                print("Done")
                     except Exception  as e:
                                print(e)

Main Class:

from Producer_Group import *
from Consumer_Group import *
from Spark_Connection import *
class client:
    def transfer(self):
        spark = connection.get_connection(self)
        producer.read_s3()
        c1 = consumer.get_consumer(spark)
        consumer.read_from_topic(self,spark)
      #  consumer.print_details(self,c1)

c=client()
c.transfer()

Sample Data in S3 that i am reading into kafka Topic:

{
    
        {
            "Customer Number": "1",
            "Customer Name": "Aditya",
            "Restaurant Number": "2201",
            "Restaurant NameOrdered": "Bawarchi",
            "Number of Items": "3",
            "price": "10",
            "Operating Start hours": "9:00",
            "Operating End hours": "23:00"
        },
        {
            "Customer Number": "2",
            "Customer Name": "Sarva",
            "Restaurant Number": "2202",
            "Restaurant NameOrdered": "Sarvana Bhavan",
            "Number of Items": "4",
            "price": "20",
            "Operating Start hours": "8:00",
            "Operating End hours": "20:00"
        },
        {
            "Customer Number": "3",
            "Customer Name": "Kala",
            "Restaurant Number": "2203",
            "Restaurant NameOrdered": "Taco Bell",
            "Number of Items": "5",
            "price": "30",
            "Operating Start hours": "11:00",
            "Operating End hours": "21:00"
        }
    
}

What Have I tried so far: : I have tried to print on console so as to check for condition and if it passes only then insert it into databse. to check the condtiion, I am reading data from "read_from_topic" function and creating a view (createOrReplaceTempView) to see data, but nothing is printing, can some one please guide me how to print and verify if My conditions or data is read correclty?

Thanks in Advance !!!!

Answer 1

creating a view (createOrReplaceTempView) to see data, but nothing is printing

Because spark.sql returns a new Dataframe.

If you want to print it, then you'll need

spark.sql("select * from kafka").show()

However, this alone will be at least two byte array columns, not JSON strings, so you'll want to define a schema at some point to extract anything or CAST to at least have human readable data

Also worth pointing out that the data you've shown is not valid JSON, and boto3 isn't necessary since Spark can read files from S3 itself (and thus Kafka isn't strictly needed since you could just take S3 data directly into your final location, with a Spark persist() function in between)