Zachary Jablons created SPARK-27609:
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Summary: [Documentation Issue?] from_json expects values of
options dictionary to be
Key: SPARK-27609
URL: https://issues.apache.org/jira/browse/SPARK-27609
Project: Spark
Issue Type: Bug
Components: PySpark
Affects Versions: 2.2.1
Environment: I've found this issue on an AWS Glue development endpoint
which is running Spark 2.2.1 and being given jobs through a SparkMagic Python 2
kernel, running through livy and all that. I don't know how much of that is
important for reproduction, and can get more details if needed.
Reporter: Zachary Jablons
When reading a column of a DataFrame that consists of serialized JSON, one of
the options for inferring the schema and then parsing the JSON is to do a two
step process consisting of:
{{#this results in a new dataframe where the top-level keys of the JSON # are
columns}}
{{df_parsed_direct = spark.read.json(df.rdd.map(lambda row: row.json_col))}}
{{# this does that while preserving the rest of df}}
{{schema = df_parsed_direct.schema}}
{{df_parsed = df.withColumn('parsed', from_json(df.json_col, schema)}}
When I do this, I sometimes find myself passing in options. My understanding
is, from the documentation
[here|http://spark.apache.org/docs/2.1.0/api/python/pyspark.sql.html#pyspark.sql.functions.from_json],
that the nature of these options passed should be the same whether I do
{{spark.read.option('option',value)}}
or
{{from_json(df.json_col, schema, options=\{'option':value})}}
However, I've found that the latter expects value to be a string representation
of the value that can be decoded by JSON. So, for example
options=\{'multiLine':True} fails with
{{java.lang.ClassCastException: java.lang.Boolean cannot be cast to
java.lang.String}}
whereas options=\{'multiLine':'true'} works just fine.
Notably, providing spark.read.option('multiLine',True) works fine!
The code for reproducing this issue as well as the stacktrace from hitting it
are provided in [this
gist|https://gist.github.com/zmjjmz/0af5cf9b059b4969951e825565e266aa].
I also noticed that from_json doesn't complain if you give it a garbage option
key – but that seems separate.
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