assert_true
Returns null if the input column is true; throws an exception with the provided error message otherwise.
Syntax
Python
from pyspark.sql import functions as sf
sf.assert_true(col, errMsg=None)
Parameters
Parameter | Type | Description |
|---|---|---|
|
| Column name or column that represents the input column to test. |
|
| 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
Python
from pyspark.sql import functions as sf
df = spark.createDataFrame([(0, 1)], ['a', 'b'])
df.select('*', sf.assert_true(df.a < df.b)).show()
Output
+---+---+--------------------------------------------+
| a| b|assert_true((a < b), '(a < b)' is not true!)|
+---+---+--------------------------------------------+
| 0| 1| NULL|
+---+---+--------------------------------------------+
Example 2: Assert with column error message
Python
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()
Output
+---+---+-----------------------+
| a| b|assert_true((a < b), a)|
+---+---+-----------------------+
| 0| 1| NULL|
+---+---+-----------------------+
Example 3: Assert with custom error message
Python
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()
Output
+---+---+---------------------------+
| a| b|assert_true((a < b), error)|
+---+---+---------------------------+
| 0| 1| NULL|
+---+---+---------------------------+