assert_true

Returns null if the input column is true; throws an exception with the provided error message otherwise.

Syntax

from pyspark.sql import functions as sf

sf.assert_true(col, errMsg=None)

Parameters

Parameter	Type	Description
col	pyspark.sql.Column or str	Column name or column that represents the input column to test.
errMsg	pyspark.sql.Column or str, optional	A Python string literal or column containing the error message.

Returns

pyspark.sql.Column: null if the input column is true otherwise throws an error with specified message.

Examples

Example 1: Assert a true condition

from pyspark.sql import functions as sf
df = spark.createDataFrame([(0, 1)], ['a', 'b'])
df.select('*', sf.assert_true(df.a < df.b)).show()

+---+---+--------------------------------------------+
|  a|  b|assert_true((a < b), '(a < b)' is not true!)|
+---+---+--------------------------------------------+
|  0|  1|                                        NULL|
+---+---+--------------------------------------------+

Example 2: Assert with column error message

from pyspark.sql import functions as sf
df = spark.createDataFrame([(0, 1)], ['a', 'b'])
df.select('*', sf.assert_true(df.a < df.b, df.a)).show()

+---+---+-----------------------+
|  a|  b|assert_true((a < b), a)|
+---+---+-----------------------+
|  0|  1|                   NULL|
+---+---+-----------------------+

Example 3: Assert with custom error message

from pyspark.sql import functions as sf
df = spark.createDataFrame([(0, 1)], ['a', 'b'])
df.select('*', sf.assert_true(df.a < df.b, 'error')).show()

+---+---+---------------------------+
|  a|  b|assert_true((a < b), error)|
+---+---+---------------------------+
|  0|  1|                       NULL|
+---+---+---------------------------+