DAX Function for Date Type Correction

Overview

This DAX function checks if a specified column contains invalid date formats and attempts to convert them to proper date types. If the conversion is unsuccessful, it will raise an error message for invalid entries.

Function Definition

CorrectDateType = 
VAR __InputDate = SELECTEDVALUE('TableName'[DateColumn])
VAR __IsDate = ISERROR(DATEVALUE(__InputDate))
RETURN 
    IF(
        __IsDate,
        ERROR("Invalid date format: " & __InputDate),
        DATEVALUE(__InputDate)
    )

Code Explanation

• SELECTEDVALUE: This function retrieves the value from the specified date column. It is essential to ensure only one value is processed at a time.
• ISERROR: This function checks if the conversion of the selected value to a date format returns an error.
• ERROR: If the value cannot be converted, this function generates a custom error message indicating an invalid date format.
• DATEVALUE: This function converts a valid date string into a date format.

Input Validation

• The function utilizes ISERROR to validate the input before attempting conversion to handles cases of incorrect input formats.
• Make sure your columns are correctly referenced and the table name matches your dataset.

Usage Example

Assuming you have a table named SalesData with a column SaleDate, and some entries are in incorrect formats:

CorrectedSaleDate = 
VAR __InputDate = SELECTEDVALUE(SalesData[SaleDate])
VAR __IsDate = ISERROR(DATEVALUE(__InputDate))
RETURN 
    IF(
        __IsDate,
        ERROR("Invalid date format: " & __InputDate),
        DATEVALUE(__InputDate)
    )

Here, CorrectedSaleDate creates a new calculated column that utilizes the CorrectDateType logic on the SaleDate to standardize date formats across the dataset.

Conclusion

This DAX function enhances data integrity in your model by ensuring that date fields are consistently formatted. It's crucial for effective analysis and reporting. For further enhancement of your DAX skills, consider exploring courses available on the Enterprise DNA Platform.