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Understanding the Contains() Function in Assette Expressions

Introduction #

In Assette, expressions are powerful tools used within Data Objects to manipulate, compare, and evaluate data for client reports and presentations. The Contains() function is an essential component in these expressions, enabling developers to determine whether a specific substring exists within a string, with the option to ignore case sensitivity.

This article provides a comprehensive overview of the Contains() function in Assette, including its purpose, syntax, usage in expressions, practical examples, and best practices for incorporating it effectively into your data processing workflows.

Purpose of Contains() #

The Contains() function is used to check whether:

• A string (mainString) contains a specific substring (subString).

It returns a boolean value:

• True: If the substring is found within the main string.
• False: If the substring is not found.

An optional ignoreCase parameter allows you to specify whether the search should be case-sensitive.

This function is crucial for:

• Conditional Logic: Making decisions based on the presence of certain values.
• Data Validation: Ensuring data meets specific criteria.
• Filtering Data: Selecting records that match certain conditions.

Syntax #

• mainString: The string to search within.
• subString: The substring to search for.
• ignoreCase: (Optional) A boolean value indicating whether to ignore case sensitivity. If set to true, the search is case-insensitive. If omitted or set to false, the search is case-sensitive.

Contains(mainString, subString, ignoreCase: true)

Usage in Expressions #

Case-Sensitive Search #

If ignoreCase is omitted or set to false, the Contains() function performs a case-sensitive search.

• Returns True only if documentTitle contains “Quarterly Report” with the exact casing.
• Returns False if the casing differs.

Contains(documentTitle, "Quarterly Report")

Case-Insensitive Search #

By setting ignoreCase to true, the Contains() function will perform a case-insensitive search.

• Returns True if documentTitle contains “Quarterly Report”, “quarterly report”, “QUARTERLY REPORT”, etc.
• Ignores case differences between mainString and subString.

Contains(documentTitle, "quarterly report", ignoreCase: true)

Practical Examples #

Filtering Transactions #

Objective: Identify if a transaction is of a specific type, considering case sensitivity.

Explanation:

• Performs a case-sensitive search for “Refund” in transactionType.
• Use this when the exact casing is important.

Contains(transactionType, "Refund")

Best Practices #

1. Specify ignoreCase When Necessary
   • Be explicit about case sensitivity by setting ignoreCase to true or false.
2. Understand Default Behavior
   • If ignoreCase is optional and omitted, know that the default is case-sensitive. Always specify ignoreCase if case insensitivity is required.
3. Trim Whitespace
   • Remove unnecessary spaces using Trim().
4. Avoid False Positives
   • Be precise with subString to prevent unintended matches.

Common Mistakes to Avoid #

• Ignoring Case Sensitivity
  • Not specifying ignoreCase can lead to missed matches or false positives.
• Assuming Default Case Sensitivity
  • If unsure about the default behavior, always specify the ignoreCase parameter.
• Not Handling Null Values
  • Attempting to use Contains() on a null mainString may cause errors.
• Assuming Exact Matches
  • Remember that Contains() searches for any occurrence of subString within mainString.