down()

Signature

down() — returns void

Available in: migration Category: Migration Functions

Description

Migrates down: will be executed when migrating your schema backward Along with up(), these are the two main functions in any migration file Only available in a migration CFC

Examples

// 1. Reverse a table creation by dropping the table
// Called automatically when rolling back this migration
function down() {
	var state = {};
	transaction {
		try {
			dropTable("employees");
		} catch (any e) {
			state.exception = e;
		}

		if (structKeyExists(state, "exception")) {
			transaction action="rollback";
			throw(
				errorCode = "1",
				detail    = state.exception.detail,
				message   = state.exception.message,
				type      = "any"
			);
		} else {
			transaction action="commit";
		}
	}
}

// 2. Reverse an addColumn() call by removing the column
function down() {
	var state = {};
	transaction {
		try {
			removeColumn(table="users", columnName="biography");
		} catch (any e) {
			state.exception = e;
		}

		if (structKeyExists(state, "exception")) {
			transaction action="rollback";
			throw(
				errorCode = "1",
				detail    = state.exception.detail,
				message   = state.exception.message,
				type      = "any"
			);
		} else {
			transaction action="commit";
		}
	}
}

// 3. Paired up() and down() inside a full migration component
component extends="[extends]" hint="Add status column to orders" {

	function up() {
		var state = {};
		transaction {
			try {
				addColumn(table="orders", columnType="string", columnName="status", limit=50, default="pending");
			} catch (any e) {
				state.exception = e;
			}

			if (structKeyExists(state, "exception")) {
				transaction action="rollback";
				throw(
					errorCode = "1",
					detail    = state.exception.detail,
					message   = state.exception.message,
					type      = "any"
				);
			} else {
				transaction action="commit";
			}
		}
	}

	function down() {
		var state = {};
		transaction {
			try {
				removeColumn(table="orders", columnName="status");
			} catch (any e) {
				state.exception = e;
			}

			if (structKeyExists(state, "exception")) {
				transaction action="rollback";
				throw(
					errorCode = "1",
					detail    = state.exception.detail,
					message   = state.exception.message,
					type      = "any"
				);
			} else {
				transaction action="commit";
			}
		}
	}

}