Advertisements

Archive

Archive for January, 2019

Spark/Scala: Convert or flatten a JSON having Nested data with Struct/Array to columns (Question)

January 9, 2019 Leave a comment

 
The following JSON contains some attributes at root level, like ProductNum and unitCount.
It also contains a Nested attribute with name “Properties”, which contains an array of Key-Value pairs.

Now, what I want is to expand this JSON, and have all the attributes in form of columns, with additional columns for all the Keys in Nested array section, like in the “Expected Output” section below:

{
   "ProductNum":"6000078",
   "Properties":[
      {
         "key":"invoice_id",
         "value":"923659"
      },
      {
         "key":"job_id",
         "value":"296160"
      },
      {
         "key":"sku_id",
         "value":"312002"
      }
   ],
   "unitCount":"3"
}

 

Expected output, as described above:

+-------------------------------------------------------+   
| ProductNum | invoice_id | job_id | sku_id | unitCount |  
+-------------------------------------------------------+   
| 6000078    | 923659     | 296160 | 312002 | 3         |  
+-------------------------------------------------------+

 

Solution:

val DS_Products = spark.createDataset("""{
   "ProductNum":"6000078",
   "Properties":[
      {
         "key":"invoice_id",
         "value":"923659"
      },
      {
         "key":"job_id",
         "value":"296160"
      },
      {
         "key":"sku_id",
         "value":"312002"
      }
   ],
   "UnitCount":"3"
}""" :: Nil)

val DF_Products = spark.read.json(DS_Products)

val df_flatten = DF_Products
  .select($"*", explode($"Properties") as "SubContent")
  .drop($"Properties")

df_flatten.show()

val df_flatten_pivot = df_flatten
  .groupBy($"ProductNum",$"UnitCount")
  .pivot("SubContent.key")
  .agg(first("SubContent.value"))

df_flatten_pivot.show()

Output:

+----------+---------+--------------------+
|ProductNum|UnitCount|          SubContent|
+----------+---------+--------------------+
|   6000078|        3|[invoice_id, 923659]|
|   6000078|        3|    [job_id, 296160]|
|   6000078|        3|    [sku_id, 312002]|
+----------+---------+--------------------+

+----------+---------+----------+------+------+
|ProductNum|UnitCount|invoice_id|job_id|sku_id|
+----------+---------+----------+------+------+
|   6000078|        3|    923659|296160|312002|
+----------+---------+----------+------+------+

 

Advertisements