How to use Spark SQL to parse the JSON array of objects

问题

now has JSON data as follows

{"Id":11,"data":[{"package":"com.browser1","activetime":60000},{"package":"com.browser6","activetime":1205000},{"package":"com.browser7","activetime":1205000}]}
{"Id":12,"data":[{"package":"com.browser1","activetime":60000},{"package":"com.browser6","activetime":1205000}]} 
......

This JSON is the activation time of app, the purpose of which is to analyze the total activation time of each app

I use sparK SQL to parse JSON

scala

val sqlContext = sc.sqlContext
val behavior = sqlContext.read.json("behavior-json.log")
behavior.cache()
behavior.createOrReplaceTempView("behavior")
val appActiveTime = sqlContext.sql ("SELECT data FROM behavior") // SQL query
appActiveTime.show (100100) // print dataFrame
appActiveTime.rdd.foreach(println) // print RDD

But the printed dataFrame is like this

.

+----------------------------------------------------------------------+

| data|

+----------------------------------------------------------------------+

| [[60000, com.browser1], [12870000, com.browser]]|

| [[60000, com.browser1], [120000, com.browser]]|

| [[60000, com.browser1], [120000, com.browser]]|

| [[60000, com.browser1], [1207000, com.browser]]|

| [[120000, com.browser]]|

| [[60000, com.browser1], [1204000, com.browser5]]|

| [[60000, com.browser1], [12075000, com.browser]]|

| [[60000, com.browser1], [120000, com.browser]]|

| [[60000, com.browser1], [1204000, com.browser]]|

| [[60000, com.browser1], [120000, com.browser]]|

| [[60000, com.browser1], [1201000, com.browser]]|

| [[1200400, com.browser5]]|

| [[60000, com.browser1], [1200400, com.browser]]|

|[[60000, com.browser1], [1205000, com.browser6], [1205000, com.browser7]]|

.

RDD is like this

.

[WrappedArray ([60000, com.browser1], [60000, com.browser1])]

[WrappedArray ([120000, com.browser])]

[WrappedArray ([60000, com.browser1], [1204000, com.browser5])]

[WrappedArray ([12075000, com.browser], [12075000, com.browser])]

.

And I want to turn the data into

.

Com.browser1 60000

Com.browser1 60000

Com.browser 12075000

Com.browser 12075000

...

.

I want to turn the array elements of each line in RDD into one row. Of course, it can be another structure that is easy to analyze.

Because I only learn spark and Scala a lot, I have try it for a long time but fail, so I hope you can guide me.

回答1:

From your given json data you can view the schema of your dataframe with printSchema and use it

appActiveTime.printSchema()
root
 |-- data: array (nullable = true)
 |    |-- element: struct (containsNull = true)
 |    |    |-- activetime: long (nullable = true)
 |    |    |-- package: string (nullable = true)

Since you have array you need to explode the data and select the struct field as below

import org.apache.spark.sql.functions._
appActiveTime.withColumn("data", explode($"data"))
       .select("data.*")
       .show(false)

Output:

+----------+------------+
|activetime|     package|
+----------+------------+
|     60000|com.browser1|
|   1205000|com.browser6|
|   1205000|com.browser7|
|     60000|com.browser1|
|   1205000|com.browser6|
+----------+------------+

Hope this helps!

回答2:

with @Shankar Koirala 's help , I learned how to use ' explode' to handle joson array.

  val df = sqlContext.sql("SELECT data FROM behavior")
appActiveTime.select(explode(df("data"))).toDF("data")
  .select("data.package","data.activetime")
  .show(false)

来源：https://stackoverflow.com/questions/49133252/how-to-use-spark-sql-to-parse-the-json-array-of-objects