问题
I am trying to parse Json structure which is dynamic in nature and load into database. But facing difficulty where json has dynamic keys inside it. Below is my sample json: Have tried using explode function but didn't help. moslty similar thing is described here How to parse a dynamic JSON key in a Nested JSON result?
{
"_id": {
"planId": "5f34dab0c661d8337097afb9",
"version": {
"$numberLong": "1"
},
"period": {
"name"
: "3Q20",
"startDate": 20200629,
"endDate": 20200927
},
"line": "b443e9c0-fafc-4791-87c9-
8e32339c7f3c",
"channelId": "G7k5_-HWRIuF0-afe7q-rQ"
},
"unitRates": {
"units": {
"$numberLong":
"0"
},
"rate": 0.0,
"rcRate": 0.0
},
"demoValues": {
"66": {
"cpm": 0.0,
"cpp": 0,
"vpvh": 0.0,
"imps"
:
0.0,
"rcImps": 0.0,
"ue": 0.0,
"grps": 0.0,
"demoId": "66"
},
"63": {
"cpm": 0.0,
"cpp": 0,
"vpvh":
0.0,
"imps": 0.0,
"rcImps": 0.0,
"ue": 0.0,
"grps": 0.0,
"demoId": "63"
},
"21": {
"cpm": 0.0,
"cpp"
:
0,
"vpvh": 0.0,
"imps": 0.0,
"rcImps": 0.0,
"ue": 0.0,
"grps": 0.0,
"demoId": "21"
}
},
"hh-imps":
0.0
}
Below is my scala code:
import org.apache.spark.sql.streaming.OutputMode
import org.apache.spark.sql.{DataFrame, Dataset, SparkSession}
import com.google.gson.JsonObject
import org.apache.spark.sql.types.{ArrayType, MapType, StringType,
StructField, StructType}
import org.codehaus.jettison.json.JSONObject
object ParseDynamic_v2 {
def main(args: Array[String]): Unit = {
System.setProperty("hadoop.home.dir", "C:\\hadoop")
val spark = SparkSession
.builder
.appName("ConfluentConsumer")
.master("local[4]")
.getOrCreate()
import spark.implicits._
val jsonStringDs = spark.createDataset[String](
Seq(
("""{"_id" : {"planId" : "5f34dab0c661d8337097afb9","version" : {"$numberLong" : "1"},"period" : {"name" : "3Q20","startDate" : 20200629,"endDate" : 20200927},"line" : "b443e9c0-fafc-4791-87c9-8e32339c7f3c","channelId" : "G7k5_-HWRIuF0-afe7q-rQ"},"unitRates" : {"units" : {"$numberLong" : "0"},"rate" : 0.0,"rcRate" : 0.0},"demoValues" : {"66" : {"cpm" : 0.0,"cpp" : 0,"vpvh" : 0.0,"imps" : 0.0,"rcImps" : 0.0,"ue" : 0.0,"grps" : 0.0,"demoId" : "66"},"63" : {"cpm" : 0.0,"cpp" : 0,"vpvh" : 0.0,"imps" : 0.0,"rcImps" : 0.0,"ue" : 0.0,"grps" : 0.0,"demoId" : "63"},"21" : {"cpm" : 0.0,"cpp" : 0,"vpvh" : 0.0,"imps" : 0.0,"rcImps" : 0.0,"ue" : 0.0,"grps" : 0.0,"demoId" : "21"}},"hh-imps" : 0.0}""")
))
jsonStringDs.show
import spark.implicits._
val df = spark.read.json(jsonStringDs)
df.show(false)
val app = df.select("demoValues.*")
app.createOrReplaceTempView("app")
app.printSchema
app.show(false)
val verticaProperties: Map[String, String] = Map(
"db" -> "dbname", // Database name
"user" -> "user", // Database username
"password" -> "****", // Password
"table" -> "tablename", // vertica table name
"dbschema" -> "public", // schema of vertica where the table will be
residing
"host" -> "localhost", // Host on which vertica is currently running
"hdfs_url" -> "hdfs://localhost:8020/user/hadoop/planheader/", // HDFS directory url in which intermediate orc file will persist before sending it to vertica
"web_hdfs_url" -> "webhdfs://localhost:50070/user/hadoop/planheader/"
)
val verticaDataSource = "com.vertica.spark.datasource.DefaultSource"
//read mode
val loadStream = df.write.format(verticaDataSource).options(verticaProperties).mode("overwrite").save()
//read stream mode
val saveToVertica: DataFrame => Unit =
dataFrame =>
dataFrame.write.format(verticaDataSource).options(verticaProperties).mode("append").save()
val checkpointLocation = "/user/hadoop/planheader/checkpoint"
val streamingQuery = df.writeStream
.outputMode(OutputMode.Append)
.option("checkpointLocation", checkpointLocation)
//.trigger(ProcessingTime("25 seconds"))
.foreachBatch((ds, _) => saveToVertica(ds)).start()
streamingQuery.awaitTermination()
}
}
expected output:
回答1:
Here you see what I did using Vertica:
I created a flex table, loaded it, and used Vertica's flex table function COMPUTE_FLEXTABLE_KEYS_AND_CREATE_VIEW() to get a view.
Turned out to be a single-row table:
-- CREATE the Flex Table
CREATE FLEX TABLE demovals();
-- copy it using the built-in JSON Parser (it creates a map container,
-- with all key-value pairs
COPY demovals FROM '/home/gessnerm/1/Vertica/supp/l.json' PARSER fjsonparser();
-- out vsql:/home/gessnerm/._vfv.sql:1: ROLLBACK 4213: Object "demovals" already exists
-- out Rows Loaded
-- out -------------
-- out 1
-- out (1 row)
-- out
-- out Time: First fetch (1 row): 112.540 ms. All rows formatted: 112.623 ms
-- the function on the next line guesses the data types in the values
-- matching the keys, stores the guessed data types in a second table,
-- and builds a view from all found keys
SELECT COMPUTE_FLEXTABLE_KEYS_AND_BUILD_VIEW('demovals');
-- out COMPUTE_FLEXTABLE_KEYS_AND_BUILD_VIEW
-- out --------------------------------------------------------------------------------------------------------
-- out Please see dbadmin.demovals_keys for updated keys
-- out The view dbadmin.demovals_view is ready for querying
-- out (1 row)
-- out
-- out Time: First fetch (1 row): 467.551 ms. All rows formatted: 467.583 ms
-- now, select from the single-row view on the flex table,
-- one row per column in the report (extended view: "\x" )
\x
SELECT * FROM dbadmin.demovals_view;
-- out -[ RECORD 1 ]---------------+-------------------------------------
-- out _id.channelid | G7k5_-HWRIuF0-afe7q-rQ
-- out _id.line | b443e9c0-fafc-4791-87c9-8e32339c7f3c
-- out _id.period.enddate | 20200927
-- out _id.period.name | 3Q20
-- out _id.period.startdate | 20200629
-- out _id.planid | 5f34dab0c661d8337097afb9
-- out _id.version.$numberlong | 1
-- out demovalues.21.cpm | 0.00
-- out demovalues.21.cpp | 0
-- out demovalues.21.demoid | 21
-- out demovalues.21.grps | 0.00
-- out demovalues.21.imps | 0.00
-- out demovalues.21.rcimps | 0.00
-- out demovalues.21.ue | 0.00
-- out demovalues.21.vpvh | 0.00
-- out demovalues.63.cpm | 0.00
-- out demovalues.63.cpp | 0
-- out demovalues.63.demoid | 63
-- out demovalues.63.grps | 0.00
-- out demovalues.63.imps | 0.00
-- out demovalues.63.rcimps | 0.00
-- out demovalues.63.ue | 0.00
-- out demovalues.63.vpvh | 0.00
-- out demovalues.66.cpm | 0.00
-- out demovalues.66.cpp | 0
-- out demovalues.66.demoid | 66
-- out demovalues.66.grps | 0.00
-- out demovalues.66.imps | 0.00
-- out demovalues.66.rcimps | 0.00
-- out demovalues.66.ue | 0.00
-- out demovalues.66.vpvh | 0.00
-- out hh-imps | 0.00
-- out unitrates.rate | 0.00
-- out unitrates.rcrate | 0.00
-- out unitrates.units.$numberlong | 0
For the children, for example:
CREATE FLEX TABLE children();
TRUNCATE TABLE children;
COPY children FROM '/home/gessnerm/1/Vertica/supp/l.json' PARSER fjsonparser(start_point='demoValues');
SELECT COMPUTE_FLEXTABLE_KEYS_AND_BUILD_VIEW('children');
\x
SELECT * FROM dbadmin.children_view;
-- out Time: First fetch (0 rows): 7.303 ms. All rows formatted: 7.308 ms
-- out Rows Loaded
-- out -------------
-- out 1
-- out (1 row)
-- out
-- out Time: First fetch (1 row): 13.848 ms. All rows formatted: 13.876 ms
-- out COMPUTE_FLEXTABLE_KEYS_AND_BUILD_VIEW
-- out --------------------------------------------------------------------------------------------------------
-- out Please see dbadmin.children_keys for updated keys
-- out The view dbadmin.children_view is ready for querying
-- out (1 row)
-- out
-- out Time: First fetch (1 row): 140.381 ms. All rows formatted: 140.404 ms
-- out -[ RECORD 1 ]---
-- out 21.cpm | 0.00
-- out 21.cpp | 0
-- out 21.demoid | 21
-- out 21.grps | 0.00
-- out 21.imps | 0.00
-- out 21.rcimps | 0.00
-- out 21.ue | 0.00
-- out 21.vpvh | 0.00
-- out 63.cpm | 0.00
-- out 63.cpp | 0
-- out 63.demoid | 63
-- out 63.grps | 0.00
-- out 63.imps | 0.00
-- out 63.rcimps | 0.00
-- out 63.ue | 0.00
-- out 63.vpvh | 0.00
-- out 66.cpm | 0.00
-- out 66.cpp | 0
-- out 66.demoid | 66
-- out 66.grps | 0.00
-- out 66.imps | 0.00
-- out 66.rcimps | 0.00
-- out 66.ue | 0.00
-- out 66.vpvh | 0.00
回答2:
Not sure how much efficient my code is but it does the job.
//reading data from json file
val df1 = spark.read.json("src/main/resources/data.json")
// defining schema here.
val schema = StructType(
StructField("planid", StringType, true) ::
StructField("periodname", IntegerType, false) ::
StructField("cpm", StringType, false)::
StructField("vpvh", StringType, false)::
StructField("imps", StringType, false)::
StructField("demoids", StringType, false)
:: Nil)
var someDF = spark.createDataFrame(spark.sparkContext
.emptyRDD[Row], schema)
val app = df1.select("demoValues.*","_id.planId","_id.period.name")
//this will have all the dynamic keys as column
val arr=app.columns
for(i <- 0 to arr.length-3) {
println("columnname: "+arr(i))
// traversing through keys to get the values .ex: demoValues.63.cpm
val cpm = "demoValues."+arr(i)+".cpm"
val vpvh = "demoValues."+arr(i)+".vpvh"
val imps="demoValues."+arr(i)+".imps"
val df2 = df1.select(col("_id.planId"),col("_id.period.name"),col(cpm),
col(vpvh),col(imps),lit(arr(i)).as("demoids"))
df2.show(false)
someDF=someDF.union(df2)
}
someDF.show()
来源：https://stackoverflow.com/questions/63392342/how-to-parse-dynamic-json-with-dynamic-keys-inside-it-in-scala