Expression String to string in Scala

Question

I am getting this whole expression as String (subCategory == "Serveware Sets") || (category == "Cookware & Bakeware") || (category == "Small Appliances") || (category == "Dinnerware & Serveware")

Now I want to convert this string to the expression so that I can directly compare the values of the subCategory and the category. How can I do the same.

are you asking how to parse it? then my question for you is, what's the grammar of your expression? — Jason Hu
– Jason Hu, Commented Feb 22, 2018 at 23:03
.. and what are these variables? What's their context? Are they Scala variables in your program or part of a DSL (e.g. DB column names, front-end related variables, ...)? Or it's related to Spark SQL maybe? Better to give more information in your question so that people can help you better. I guess maybe you have a fixed set of variables and you have an expression to parse, so it really depends on the grammar. — Nader Ghanbari
– Nader Ghanbari, Commented Feb 22, 2018 at 23:45

Raphael Roth · Accepted Answer · 2018-02-22 19:30:42Z

1

This can be done using expr:

val filterExpression = """(subCategory == "Serveware Sets") || (category == "Cookware & Bakeware") || (category == "Small Appliances") || (category == "Dinnerware & Serveware")"""

import org.apache.spark.sql.functions.expr

df
 .where(expr(filterExpression))

answered Feb 22, 2018 at 19:30

Raphael Roth

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2 Comments

Nader Ghanbari Over a year ago

Well this is valid if the question is asked in the context of Spark SQL.

Anahcolus Over a year ago

@RaphaelRoth, I guess || symbol need to be changed to or string for the expr to work. isn't it?

Anahcolus · Accepted Answer · 2018-02-25 13:58:06Z

0

You can change the || symbol to or so that your expression becomes

(subCategory == "Serveware Sets") or (category == "Cookware & Bakeware") or (category == "Small Appliances") or (category == "Dinnerware & Serveware")

And then you should be able to use the string expression in filtering or selecting rows from dataframes.

answered Feb 25, 2018 at 13:58

Anahcolus

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