collectionNameIsCamelCase

collectionNameIsCamelCase is a custom policy check that ensures collection names use camelCase.

Learn how to create and customize the collectionNameIsCamelCase Liquibase Custom Policy Check using a Python script.

This example utilizes MongoDB or DocumentDB. You can use this check as it is or customize it further to fit your needs in your NoSQL database.

For a conceptual overview of this feature, see Liquibase Pro Custom Policy Checks.

Scope	Database
changelog	MongoDB and DocumentDB

Step-by-step

These steps describe how to create the Custom Policy Check. It does not exist by default in Liquibase Pro.

1. Create a Check Settings file: Use the Checks Settings Configuration File

2. Add this code to your Checks Settings file:

   Copy

   collectionNameIsCamel Case Python Script

   ###
   ### This script checks for camelCase collection names during createCollection
   ###
   ### Notes:
   ### 1. Only basic createCollection statements are supported
   
   ###
   ### Helpers come from Liquibase
   ###
   import re
   import sys
   import liquibase_utilities
   
   
   def find_substring_indices(string_list, substring):
       """
       Finds the indices of list elements containing a specified substring.
   
       Args:
           string_list: A list of strings.
           substring: The substring to search for.
   
       Returns:
           A list of indices where the substring is found, or an empty list if not found.
       """
       return [index for index, string in enumerate(string_list) if substring in string.casefold()]
   
   def is_camel_case(input_string):
       """
       Checks if a string is in camel case.
   
       A string is considered camel case if it:
       - Contains only letters (a-z, A-Z) and optionally numbers (0-9).
       - Contains both lowercase and uppercase letters.
       - Does not start with a number.
   
       Args:
           input_string: The string to check.
   
       Returns:
           True if the string is in camel case, False otherwise.
       """
       if not isinstance(input_string, str):
           return False
   
       if not re.match(r"^[a-zA-Z][a-zA-Z0-9]*$", input_string):
           return False
   
       if input_string[0].isdigit():
           return False
       
       if not any(char.islower() for char in input_string) or not any(char.isupper() for char in input_string):
         return False
   
       return True
   
   def extract_substring(text, start_char, end_char):
       """
       Extracts the substring between the first occurrence of start_char and end_char in text.
   
       Args:
           text: The string to search within.
           start_char: The character marking the beginning of the substring.
           end_char: The character marking the end of the substring.
   
       Returns:
           The extracted substring, or an empty string if start_char or end_char are not found,
           or if end_char appears before start_char.
       """
       try:
           start_index = text.index(start_char) + 1
           end_index = text.index(end_char, start_index)
           return text[start_index:end_index]
       except ValueError:
           return ""
   
   
   ###
   ### Retrieve log handler
   ### Ex. liquibase_logger.info(message)
   ###
   liquibase_logger = liquibase_utilities.get_logger()
   
   ###
   ### Retrieve status handler
   ###
   liquibase_status = liquibase_utilities.get_status()
   
   ###
   ### Retrieve all changes in changeset
   ###
   changes = liquibase_utilities.get_changeset().getChanges()
   
   ###
   ### Loop through all changes
   ###
   for change in changes:
       ###
       ###
       ### Split mongo code into a list of strings to remove whitespace
       ###
       js_list = liquibase_utilities.generate_sql(change).split()
       # print (list(js_list))
       ###
       ### Locate createCollection in list
       ###
   
       if any("createcollection" in element for element in map(str.casefold, js_list)):
   
           ### Get all indexes consisting of "createCollection", irrelevant of case
           ### Returns indices as list
           indices = find_substring_indices(js_list, "createcollection")
   
           for index in indices:
               collection = js_list[index]
   
               ### Look for collection name in this format: 
               ### db.createCollection('collectionName');
               collectionName = extract_substring (collection, "'", "'")
   
               ### Account for spaces like this:
               ### db.createCollection( 'collectionName');
               if not collectionName:
                   collectionName = extract_substring (js_list[index+1], "'", "'")
   
               isCamelCase = is_camel_case(collectionName)
               print ("index=" + str(index) + ", " + str(collection) + ", ", str(collectionName) + ", ", str(isCamelCase))
   
               if not isCamelCase:
                   liquibase_status.fired = True
                   status_message = "Collection name \"" + f"{collectionName}" + "\" is NOT camelCase."
                   liquibase_status.message = status_message
                   sys.exit(1)
   
   ###
   ### Default return code
   ###
   False

3. Initiate the customization process. In the CLI, run this command:
   liquibase checks customize --check-name=CustomCheckTemplate
   The CLI prompts you to finish configuring your file. A message displays:

   This check cannot be customized directly because one or more fields does not have a default value.

   Liquibase will then create a copy of CustomCheckTemplate and initiate the customization workflow.

4. Give your check a short name so you can easily identify what Python script it is associated with (up to 64 alpha-numeric characters only).
   In this example we will name the check:
   collectionNameIsCamelCase

5. Set the Severity to return a code of 0-4 when triggered. These severity codes allow you to determine if the job moves forward or stops when this check triggers.
   Learn more here: Use Policy Checks in Automation: Severity and Exit Code
   options: 'INFO'=0, 'MINOR'=1, 'MAJOR'=2, 'CRITICAL'=3, 'BLOCKER'=4

6. Set SCRIPT_DESCRIPTION. In this example, we will set the description to:

   This script ensures collection names use camelCase.

7. Set SCRIPT_SCOPE. In this example, we will set the scope to changelog.
• changelog: for example, if your check looks for syntax patterns or attributes in your Liquibase Changelog (the changes you author in your repository). With this value, the check runs once per changeset.
8. Set the SCRIPT_MESSAGE. This message will display when the check is triggered. In this example we will use:
   Table name "myaccounts" is NOT camelCase. It is recommended you fix the casing before proceeding.
9. Set the SCRIPT_PATH. This is the relative path where your script is stored in relation to the changelog specified in --changelog-file, whether it is stored locally or in a repository.
   In this example, we will set the path to: scripts/collection-camel-case.py.
10. This Custom Policy Check does not need a SCRIPT_ARGUMENT, so leave it blank.
11. Set the REQUIRES_SNAPSHOT. If your script scope is changelog, set whether the check requires a database snapshot. Specify true if your check needs to inspect database objects. (If your script scope is database, Liquibase always takes a snapshot, so this prompt does not appear.)

Note: The larger your database, the more performance impact a snapshot causes. If you cannot run a snapshot due to memory limitations, see Memory Limits of Inspecting Large Schemas.

You have now successfully created and customized a policy check!

Next steps

• Run a Custom Policy Check

Related Topics

Sample Custom Policy Check Scripts