Spark - convert JSON array object to array of string - apache-spark

Question

as part of my dataframe, one of the column has data in following manner
[{"text":"Tea"},{"text":"GoldenGlobes"}]
And I want to convert that as just array of strings.
["Tea", "GoldenGlobes"]
Would someone please let me know, how to do this?

Answer 1

See the example below without udf:
import pyspark.sql.functions as f
from pyspark import Row
from pyspark.shell import spark
from pyspark.sql.types import ArrayType, StructType, StructField, StringType
df = spark.createDataFrame([
Row(values='[{"text":"Tea"},{"text":"GoldenGlobes"}]'),
Row(values='[{"text":"GoldenGlobes"}]')
])
schema = ArrayType(StructType([
StructField('text', StringType())
]))
df \
.withColumn('array_of_str', f.from_json(f.col('values'), schema).text) \
.show()
Output:
+--------------------+-------------------+
| values| array_of_str|
+--------------------+-------------------+
|[{"text":"Tea"},{...|[Tea, GoldenGlobes]|
|[{"text":"GoldenG...| [GoldenGlobes]|
+--------------------+-------------------+

Answer 2

If the type of your column is array then something like this should work (not tested):
from pyspark.sql import functions as F
from pyspark.sql import types as T
c = F.array([F.get_json_object(F.col("colname")[0], '$.text')),
F.get_json_object(F.col("colname")[1], '$.text'))])
df = df.withColumn("new_col", c)
Or if the length is not fixed (I do not see a solution without an udf) :
F.udf(T.ArrayType())
def get_list(x):
o_list = []
for elt in x:
o_list.append(elt["text"])
return o_list
df = df.withColumn("new_col", get_list("colname"))

Answer 3

Sharing the Java syntax :
import static org.apache.spark.sql.functions.from_json;
import static org.apache.spark.sql.functions.get_json_object;
import static org.apache.spark.sql.functions.col;
import org.apache.spark.sql.types.StructType;
import org.apache.spark.sql.types.DataTypes;
import org.apache.spark.sql.types.StructField;
import static org.apache.spark.sql.types.DataTypes.StringType;
Dataset<Row> df = getYourDf();
StructType structschema =
DataTypes.createStructType(
new StructField[] {
DataTypes.createStructField("text", StringType, true)
});
ArrayType schema = new ArrayType(structschema,true);
df = df.withColumn("array_of_str",from_json(col("colname"), schema).getField("text"));