Substituting Properties in Changelogs

Liquibase allows a dynamic substitution of properties in your changelog. The tokens to replace in your changelog are described using the ${property-name} syntax.

Uses

By substituting values for replacement tokens in the format of ${property-name}, you can use the same changesets to reflect small environmental changes.

For example, your tablespace name in Oracle may differ from environment to environment, but you want to only write one create table changeset that can be used in all your environments.

Using property substitution in your changelog

You can set property values in Liquibase in several ways. Liquibase assigns these values in the following order:

As an attribute passed to your Liquibase runner. See the Ant, Maven, or Servlet Listener documentation for more information on how to pass them.
As a JVM system property. See JAVA_OPTS Environment Variable for more information.
As an environment variable. See Liquibase Environment Variables for more information.
As a CLI attribute, if executed from the command line.
In the parameters block (property element of the DATABASECHANGELOG table itself).

Once a property has been set, it cannot be changed. Also, only the first definition is used, others are skipped.

Note: If the content of ${property-name} does not match a property, it is left as-is and it is not removed. The supported format includes alphanumeric characters, +, -, . , and _.

Note: If you do not want to replace an otherwise matching ${property-name} expression, add : to the beginning of the expression. An expression of ${: property-name} will always be converted to ${property-name} regardless of whether property-name is defined.

Nested properties

Name	Description	Required for	Supports	Multiple allowed?
`<property>`	Defined before changesets in the changelog	Substituting portions of a changeset during runtime	All supported changeset tokens	No. Property names are unique and can only be set one.

Available attributes

Attribute	Description
`name`	The name of the parameter. Required if `file` is not set
`value`	The value of the property. Required if `file` is not set
`file`	The name of the file from which the properties should be loaded. It will create a property for all properties in the file. The content of the file must follow the Java properties file format.
`context`	Contexts in which the property is valid. Expected as a comma-separated list.
`dbms`	The type of a database which that property is to be used. When the migration step is running, it checks the database type against this attribute. Valid database type names are listed on the supported databases page. It is possible to list multiple databases separated by commas. You can also specify that a changeset is not applicable to a particular database type by prefixing with `!`. The keywords `all` and `none` are also available.
`global`	Boolean. The attribute defines whether the property is global or limited to the actual DATABASECHANGELOG. The default value is `true`.

SQL Example

--liquibase formatted sql

--changeset example:1
CREATE TABLE ${schema.name}.person
( id int primary key,
  first_name varchar(50) NOT NULL,
  last_name varchar(50) NOT NULL
)

Using the example changelog and running the liquibase update-sql command with the configured environment variable schema.name=dev_schema, you will receive the following SQL output: CREATE TABLE dev_schema.person.

XML Example

<databaseChangeLog
	xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:ext="http://www.liquibase.org/xml/ns/dbchangelog-ext"
	xmlns:pro="http://www.liquibase.org/xml/ns/pro"
	xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
		http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-latest.xsd
		http://www.liquibase.org/xml/ns/dbchangelog-ext http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-ext.xsd
		http://www.liquibase.org/xml/ns/pro http://www.liquibase.org/xml/ns/pro/liquibase-pro-latest.xsd">			
	<property  name="clob.type"  value="clob"  dbms="oracle,postgresql"/>
	<property  name="clob.type"  value="longtext"  dbms="mysql"/>
	<property  name="table.name"  value="tableA"/>
				
	<changeSet  id="1"  author="joe">
		<createTable  tableName="${table.name}">
			<column  name="id"  type="int"/>
			<column  name="${column1.name}"  type="${clob.type}"/>
			<column  name="${column2.name}"  type="int"/>
		</createTable>
	</changeSet>
</databaseChangeLog>

YAML Example

databaseChangeLog:
  -  property:
        dbms:  oracle,postgresql
        name:  clob.type
        value:  clob
  -  property:
        dbms:  mysql,mariadb
        name:  clob.type
        value:  longtext
  -  property:
        name:  table.name
        value:  tableA
  -  changeSet:
          id:  1
          author:  joe
          dbms: mariadb
          changes:
          -  createTable:
               tableName:  ${table.name}
               columns:
                 -  column:
                      name:  id
                      type:  int
                 -  column:
                      name:  Column1
                      type:  ${clob.type}
                 -  column:
                      name:  Column2
                      type:  int

JSON Example

{
	"databaseChangeLog": {
	   "property": [
		  {
			"_name": "clob.type",
			"_value": "clob",
			"_dbms": "oracle,postgresql"
		  },
		  {
			"_name": "clob.type",
			"_value": "longtext",
			"_dbms": "mysql"
		  },
		  {
			"_name": "table.name",
			"_value": "tableA"
		  }
		],
		"changeSet": {
		   "createTable": {
			  "column": [
		  {
			"_name": "id",
			"_type": "int"
		  },
		  {
			"_name": "${column1.name}",
			"_type": "${clob.type}"
		  },
		  {
			"_name": "${column2.name}",
			"_type": "int"
		      }
		    ],
			"_tableName": "${table.name}"
		  },
			"_id": "1",
			"_author": "joe"
		  },
			"_xmlns": "http://www.liquibase.org/xml/ns/dbchangelog",
			"_xmlns:xsi": "http://www.w3.org/2001/XMLSchema-instance",
			"_xmlns:ext": "http://www.liquibase.org/xml/ns/dbchangelog-ext",
			"_xsi:schemaLocation": "http://www.liquibase.org/xml/ns/dbchangelog 
		    http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-4.8.0.xsd
		    http://www.liquibase.org/xml/ns/dbchangelog-ext
		    http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-ext.xsd"
	     }
     }