What are Liquibase Python modules?
Last updated: July 14, 2025
Liquibase provides an API you can call on in your Python Liquibase Pro Custom Policy Checks. The Liquibase Checks extension comes with several modules you can import in your scripts to access this API:
- liquibase_changesets - liquibase_constants - liquibase_database - liquibase_json - liquibase_utilities
This documentation page lists the callable methods and functions contained in these Python modules. You can use these to access necessary information about your changelog and database to run your Custom Policy Checks.
The Liquibase Python modules are a layer on top of the Liquibase API, which is written in Java (Javadocs). They contain functions that wrap many of the native Java methods Liquibase uses. This allows you to access Liquibase functions in a more Pythonic way to improve ease of use and interoperability. However, it is still possible to call directly on Java methods in your Python code.
For real-world Python scripts that access these modules, see Sample Custom Policy Check Scripts.
Python modules
The Python Standard Library is included when you download Python. Liquibase also natively supports the following Python modules:
These modules can provide additional functionality in your Custom Policy Checks, such as parsing complex SQL queries.
The built-in Liquibase virtual environment cannot support additional modules. If you want to use more, you must create your own virtual environment and configure Liquibase to run scripts using your custom executable instead.
In your custom virtual environment, you can install the Liquibase Python modules and natively supported Python modules in a package called liquibase-checks-python. For more information, see Create a Python Virtual Environment.
Import syntax
By default, you can import Liquibase modules using the following syntax:
import <module name>
If you use a custom virtual environment instead of the built-in virtual environment Liquibase provides, you must use the following syntax instead:
from liquibase-checks-python import <module name>
liquibase_changesets
These functions are available to you after importing liquibase_changesets.
Functions to pull information from the given changeset path. The changeset is always the input parameter for these attributes.
Property | Value |
get_author(changeset) | Returns the changeset author |
get_contexts(changeset) | Returns the changeset contexts |
get_file_path(changeset) | Returns the changeset file path |
get_id(changeset) | Returns the changeset ID |
get_labels(changeset) | Returns the changeset labels |
is_always_run(changeset) | Returns the value of runAlways for this changeset |
is_run_on_change(changeset) | Returns the value of runOnChange for this changeset |
liquibase_database
These functions are available to you after importing liquibase_database.
Methods to access, or return, database attributes. The database is always the input parameter for these attributes.
Function | Return |
get_database_product_name(database) | Returns the database product name |
get_database_product_version(database) | Returns the database product version |
get_default_schema_name(database) | Returns the default schema for this database |
get_short_name(database) | Returns the database short name |
liquibase_json
These functions are available to you after importing liquibase_json.
Functions to access, or return, JSON attributes. These are functions to parse a JSON snapshot of your database and access, or return, dictionary objects.
Function | Input Parameter | Return |
get_column | snapshot: the snapshot to parsetable_name: the name of the table to search forcolumn_name: the name of the column to search for | Returns the specified Column Dict object for a table |
get_column_size | column: the Column Dict object | Returns the specified Column's size |
get_column_type_name | column: the Column Dict object | Returns the specified Column's type name |
get_columns | snapshot: the snapshot to parsetable_name: the name of the table to search for | Returns a list of Column Dict objects for a table such as a JSON serialized representation of the Liquibase internal DatabaseObject class.Example output:{'column': {'name': 'name', 'nullable': True, 'order': '1!{java.lang.Integer}', 'relation': 'liquibase.structure.core.Table#0eab104', 'snapshotId': '0eab105', 'type': {'characterOctetLength': '20!{java.lang.Integer}', 'columnSize': '20!{java.lang.Integer}', 'columnSizeUnit': 'BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}', 'dataTypeId': '1!{java.lang.Integer}', 'radix': '10!{java.lang.Integer}', 'typeName': 'bpchar'}}} |
get_indexes | snapshot: the snapshot to parsetable_name: the name of the table to search for | Returns a List of Index Dict objects for a table |
get_primary_key | snapshot: the snapshot to parsetable_name: the name of the table to search for | Returns a Primary Key Dict object for a table |
get_table | snapshot: the snapshot to parsetable_name: the name of the table to search for | Returns the requested table object |
get_tables | snapshot: the snapshot to parse | Returns a list of Table Dict objects |
liquibase_utilities
These functions are available to you after importing liquibase_utilities.
Utilities are general script helpers that retrieve content frequently searched for.
Function | Input Parameter(s) | Return |
generate_sql | change: the change to generate SQL from | Returns the SQL associated with this change that Liquibase would deploy to your database. The function returns any inline SQL (formatted SQL or sql Change Type) or SQL within referenced files (sqlFile) it finds. Otherwise, it generates SQL from any modeled Change Types (like createTable) it finds, similar to running the update-sql command. Does not include Liquibase-specific SQL, like updates to the DATABASECHANGELOG table.Example:changes = liquibase_utilities.get_changes()sql = liquibase_utilities.generate_sql(change[0])if "something bad" in sql:status.fired = Truesys.exit(1) # exit from the check |
get_arg | name: the argument to find | Return the value of the script argument you specified while creating or customizing your check in the CLI. For example, if you specify MAX_SIZE=10 in the CLI, you can retrieve it in your code with a variable: max_size = int(liquibase_utilities.get_arg("MAX_SIZE")). |
get_binding | key: the binding to access | Returns the binding object at the given key |
get_cache | key: the look up keydefault_value: the value to put for the key if no value present | Returns the stored key/value pairs currently held by a dict object that are available between script executions. For example, you can count the number of times a check triggers by adding a counter that updates for each feature. If there is no current value, returns the default value. |
get_changes | Returns the set of Liquibase change objects that the check is actively examining. Custom policy checks run against a single changeset at a time, so this refers to a list of Change Types within a single changeset. | |
get_changeset | Returns the changeset object Liquibase is actively examining | |
get_column_type | database_object: the database object to check | Returns the data type of the column of a database object. Examples include: varchar, integer, etc. If the database object is not a column, returns None. |
get_database | Returns the Liquibase database object | |
get_database_object | Return the DatabaseObject that is being referenced in a database-scoped check | |
get_database_snapshot | Return the DatabaseSnapshot object as a string | |
get_dbutil | Return the db_util object used to check for object existence or to snapshot the DatabaseObject and return it | |
get_logger | Return the Liquibase logger | |
get_object_type_name | database_object: the database_object to return the type for | Return the object type of a given database object as a string |
get_script_message | Return the message for the script. This is the message you specify in the CLI when you create a custom policy check. | |
get_script_path | Return the path of the script. This is the path you specify in the CLI when you create a custom policy check. | |
get_snapshot | Return the snapshot as a JSON object. If no snapshot is available, return None. | |
get_status | Return the Status object, which is used to set the check fired status and return a message. Required to tell Liquibase whether a check has triggered. | |
has | object_type: the object typeschema_name: the schema nameobject_name: the object name | Returns true if there is an object of this type and name in the schema, false otherwise |
has_relation | object_type: the object typeobject_name: the object namerelation_type: the type of relation (Table or View)relation_schema_name: the schema of the relation objectrelation_name: the name of the relation | Returns true if there is an object of this type that has a relation object that matches the relation type, schema, and name. Returns false if no items match the provided criteria. |
is_catalog | database_object: the database object to check | Returns true if the database object is a catalog, false otherwise |
is_check_constraint | database_object: the database object to check | Return true if the database object is a check constraint, false otherwise |
is_column | database_object: the database object to check | Return true if the database object is a column, false otherwise |
is_database_package | database_object: the database object to check | Return true if the database object is a database package, false otherwise |
is_database_package_body | database_object: the database object to check | Return true if the database object is a database package body, false otherwise |
is_foreign_key | database_object: the database object to check | Return true if the database object is a foreign key, false otherwise |
is_function | database_object: the database object to check | Return true if the database object is a function, false otherwise |
is_index | database_object: the database object to check | Return true if the database object is an index, false otherwise |
is_primary_key | database_object: the database object to check | Return true if the database object is a primary key, false otherwise |
is_schema | database_object: the database object to check | Return true if the database object is a schema, false otherwise |
is_sequence | database_object: the database object to check | Return true if the database object is a sequence, false otherwise |
is_stored_database_logic | database_object: the database object to check | Return true if the database object is stored database logic, false otherwise |
is_stored_procedure | database_object: the database object to check | Return true if the database object is a stored procedure, false otherwise |
is_synonym | database_object: the database object to check | Return true if the database object is a synonym, false otherwise |
is_table | database_object: the database object to check | Return true if the database object is a table, false otherwise |
is_trigger | database_object: the database object to check | Return true if the database object is a trigger, false otherwise |
is_unique_constraint | database_object: the database object to check | Return true if the database object is a unique constraint, false otherwise |
is_view | database_object: the database object to check | Return true if the database object is a view, false otherwise |
put_cache | key: the key to usevalue: the value to put in the cache | Places the stored key/value pairs held by a dict object that are available between script executions. |
query_for_list | sql: the SQL to executesql_file: the SQL file to executeend_delimiter: the end delimiter to use | Executes a SQL statement or script. Returns the result of the SQL as a list |
snapshot_object | object_type: the type of the object, like Tableobject_name: the objects namerelation_type: a type of relation that we need to snapshot to access the objectschema_name: the schema for the relationrelation_name: the name of the relation | Returns a Liquibase model object that represents the database object specified |
split_sql | sql_string: the SQL to processstrip_comments_flag: set to true to strip out commentsend_delimiter: the end delimiter to use while processing the SQLchangeset: the change set associated with the SQL | Returns an array of SQL lines |
split_statements | sql_string: the SQL string to split | Splits a string of SQL into individual statements. Returns the list of SQL strings |
strip_comments | sql_string: the SQL to strip | Strips comments from a SQL string. Returns the SQL string with comments removed |
tokenize | statement: the statement to tokenize | Tokenizes a statement which was created by the sqlparse Python module. Returns the tokenized statement as a list |
liquibase_constants
These functions are available to you after importing liquibase_constants.
Constants are an unchangeable set of well-known constants that are used to access the script bindings. They are definitions of internal Python classes Liquibase uses to enable Custom Policy Checks via Python scripts.
Warning: You should be familiar with what a Python class is and how classes can have variables which are the equivalent of a constant. Most users will not need to use these unless you are debugging a complex custom policy check you have created.
Constant methods
__init__(self)__setattr__(self, name, value)
Constant data descriptors
__dict____weakref__
ScriptConstant data descriptors
__dict____weakref__
ScriptConstant data and other attribute definitions
ARGS_SUFFIX = '_arg_binding'CACHE_BINDING = 'cache_binding'CHANGESET_BINDING = 'changeSet_binding'CHANGES_BINDING = 'changes_binding'DATABASE_BINDING = 'database_binding'DATABASE_OBJECT_BINDING = 'databaseObject_binding'DATABASE_SNAPSHOT_BINDING = 'databaseSnapshot_binding'DBUTIL_BINDING = 'dbutil_binding'LOGGER_BINDING = 'logger_binding'SCRIPT_MESSAGE_BINDING = 'scriptMessage_binding'SCRIPT_PATH_BINDING = 'script_path_binding'STATUS_BINDING = 'status_binding'