Move into Drupal using the Migrate Module

NYC Camp 2012Ashok Modi (BTMash)

Agenda

● Introduction to Migrate● Theory● Implementation

○ Hooks○ Classes

■ Migration■ Handlers■ Alterations

● Commands / Demo (Time Permitting)● Q & A (Conclusion)

Thanks

● Mike Ryan (mikeryan)○ http://drupal.org/user/4420

● Moshe Weitzman (moshe weitzman)○ http://drupal.org/user/23

● Frank Carey○ http://drupal.org/user/112063

● Andrew Morton (drewish)○ http://drupal.org/user/34869

Introduction to Migrate - Options

● What are your options to bring content over into Drupal?○ By Hand

■ Very time consuming.■ Not feasible if you have a 'lot' of content.

● If you really don't like who you work with.○ Custom Scripts

■ Might be ok as a 'one-off' solution.■ As flexible as you want.■ Write out drush plugins/web ui.■ Tracking?■ Integration into your source?

Introduction to Migrate - Options

Feeds● Absolutely great option.● Easy to setup.● Maps fields from source -> destination● Can Import RSS / Atom / Various Feeds

○ Plugins for CSV, Database, even LDAP● Well documented.● Performance issues.● Content update handling.● Doesn't work well wrt references from other

content (types).

Introduction to Migrate

● Powerful object oriented framework for moving content into Drupal.

● Already defined many import sources.○ XML, JSON, CSV, DB, etc.

● Support to migrate into various types of content.○ users, nodes, comments, taxonomy, all core entities.○ can define your own import handler.○ can import into a particular table!

● Fast.● Minimal UI, mainly steered around drush.● Drush integration.● Steep Learning Curve.

○ You will write code.

Introduction to Migrate

● Drupal 6 requires autoload and dbtng modules. So the code is very similar in 6 and 7.

● Migrate Extras provides support for many contrib modules.○ Provides base class for importing to entities from

EntityAPI.○ More field modules implementing field handlers.

● The most comprehensive and up-to-date documentation is the beer.inc and wine.inc examples.○ Part of the Migrate module.

Goal

Sourcesidtitleuserfield1field2

...fieldN

Destinationcontent_id(auto)

titleuid

field1field2

...fieldN

Source

● Interface to your current set of data (csv, json, xml, db, etc).

● Provides a list of fields.● Responsible for iterating over the rows of

data.

Destination

● Responsible for saving specific type of content to Drupal (user, node, row in a particular table)

● Each Source record correlates to one Destination record.

Field Mappings

● Links a source field to destination field.● Basic functions such as splitting into an

array based on separators, etc.● Can pass additional arguments (as the field

handler implements).

Mapping (goal)

Sourcesidtitleuserfield1field2field3field4

...

fieldN

Destinationcontent_id(auto)

titleuid

field1field2

...fieldN

Mapping (alter and reference)

Mapping

Map

● Connects the source and destination IDs allowing for translation between them.

● Tracks keys schema format.● Allows for migration to re-run and update

existing records.● Allows imported records to be deleted.● Allows you to reference the ID from another

migration for to get converted for your own migration.

Migration Map

Sourcesidtitleuserfield1field2field3field4

...

fieldN

Destinationcontent_id(auto)

titleuid

field1field2

...fieldN

Mapping (alter and reference)

Mapping

Map Table

Migration

● Sets up all the necessary pieces: Source, Destination, Map, Field Mappings.

● May provide logic for skipping over rows during migration.

● May alter the Source Data during the migration.

● May alter the Destination Entities during the Migration.

Field Handler

● Converts your source data into a format that Drupal understands.

● $row->bar = array('foo', 'bar') into$entity_field_bar = array( 'und' => array( 0 => array('value' => 'foo'), 1 => array('value' => 'bar'), ),);

Destination Handler

● Extends existing destinations and adds additional functionality.○ MigrateCommentNodeHandler provides the option to

allow for comments to a given node.● Contrib projects might want to create these.

○ Flag?

Field Handler

Sourcesidtitleuserfield1field2field3field4

...

fieldN

Destinationcontent_id(auto)

title (text)uid

field1 (text)field2 (image)

...fieldN (tags)

Mapping (alter and reference)

Mapping

Map Table

Implementation

● Let Migrate know about your module (hook).● Build a migration class.

○ Provide a description.○ Give it information about where the content is coming from (Source).○ Give it information about where the content is going to get saved

(Destination).○ Map the fields from the source into the destination (Map).○ (optional) Massage the data / add any fields you were not able to get

in the initial mapping.○ (optional) Add / massage any data that does not have field handlers

before the content gets saved.

● Register class file in .info file.

Implementation - Hooks

● Just one :)○ Provide the API version number (currently at 2)

function my_migrate_module_migrate_api() { return array( 'api' => 2, );}

● Might change to 3/4/5...N in the future ;)

Implementation - Class

● Consists of at least 1 function and 3 optional functions.

class MYBundleMigration extends Migration { public function __construct() { ... } # REQ'D. public function prepareRow($row) public function prepare($entity, $row) public function complete($entity, $row)}

Import Flow

● Source iterates until it finds an appropriate record.● Calls prepareRow($row) letting you modify or reject the

data in $row.● Migration applies the Mappings and Field Handlers to

convert $row into $entity.● Migrate calls on prepare($entity, $row) to modify the

entity before it gets saved.● Entity is saved.● Migrate records the IDs into the map and calls

complete() so you can see and work with the final Entity ID.

Implementation - __construct()

● Set up the source, destination, map, field mappings in constructor.

class MyBundleMigration extends Migration { public function __construct() { parent::__construct(); $this->source = <my_source>; $this->destination = <my_destination>;

$this->map = <my_map>;$this->addFieldMapping($my_dest_fld, $my_src_fld);

}}

Implementation - __construct() Source Fields

● Lets Migration class know a little about the fields that are coming in (like compound fields).

● Can set it to an array if nothing complex.$source_fields = array( 'mtid' => 'The source row ID', 'compound_field_1' => 'Field not from inital query but will be necessary later on.');

Implementation - __construct() Source (Current Database)

// Required$query = db_select('my_table', 'mt');$query->fields('mt', array('mtid', 'style', 'details', 'updated', 'style_parent', 'style_image'));$query->join('mt_extras', 'mte', 'mt.mtid = mte.mtid');$query->orderBy('mt.updated', 'ASC');// Implement a count_query if it is different. Or set to NULL.$this->source = new MigrateSourceSQL($query, $source_fields, $count_query);

Implementation - __construct() Source (External Database)

// Using another db connection called 'for_migration'.$connection = Database::getConnection('for_migration');$query = $connection->select('my_table', 'mt');$query->fields('mt', array('mtid', 'style', 'details', 'updated', 'style_parent', 'style_image'));$query->orderBy('mt.updated', 'ASC');// Implement a count_query if it is different. Or set to NULL.$this->source = new MigrateSourceSQL($query, $source_fields, $count_query, array('map_joinable' => FALSE'));● Lets migrate know there is no easy way to map the IDs.

Implementation - __construct() Source (CSV File)// The definition of the columns. Keys are integers// values are an array of: field name then description. $columns = array(

0 => array('cvs_uid', 'Id'), 1 => array('email', 'Email'), 2 => array('name', 'Name'), 3 => array('date', 'Date'),

);

$this->source = new MigrateSourceCSV("path/to/file.csv", $columns, array('header_rows' => TRUE), $this->fields());

Implementation - __construct() Source (Other Sources)

● Comes with base source migration classes to migrate from JSON, XML, File Directories.

● Expect to make some changes depending on the migration format.

Source Base Classes

● If you have source IDs referenced separately from your values.○ Use MigrateSourceList as a source.○ Implement MigrateList for fetching counts and IDs, and MigrateItem for

fetching values.

● If everything is in a single file with IDs mixed in:○ Use MigrateSourceMultiItems as a source.○ Implement MigrateItems for extracting IDs and values.

● Look at http://drupal.org/node/1152152, http://drupal.org/node/1152154, and http://drupal.org/node/1152156 for clearer examples.

Implementation - __construct() Migration Map

$this->map = new MigrateSQLMap($this->machineName, // Describe your primary ID schema array( 'mtid' => array( 'type' => 'integer', 'unsigned' => TRUE, 'not null' => TRUE, 'alias' => 'mt' ), ), MigrateDestinationNode::getKeySchema());

Implementation - __construct() Highwater

● May have noticed orderby on sql queries.● Migrate feature to figure out if a piece of

content can be updated rather than inserted just once.

● Need to let migrate know which column contains the highwater data.

$this->highwaterField = array( 'name' => 'updated', 'alias' => 'mt',);

Implementation - __construct() Destination// Terms$this->destination = new MigrateDestinationTerm('site_vocabulary');

// Nodes$this->destination = new MigrateDestinationNode('articles');

// Users$this->destination = new MigrateDestinationUser();

// Contrib - Commerce Products$this->destination = new MigrateDestinationEntity('commerce_product');

Implementation - __construct()Field Mapping// Can be simple.$this->addFieldMapping('dest_name', 'source_name');

// Can be a set value.$this->addFieldMapping('uid')->defaultValue(1);

// Can have no value (or whatever the system default is)$this->addFieldMapping('path')->issueGroup('DNM');

// Can be multiple values with a separator.$this->addFieldMapping('field_tags', 'source_tags')->separator(',');

// Can have arguments$this->addFieldMapping('field_body', 'description')->arguments($arguments);

Implementation - __construct()Field Mapping (cont'd)

● Most meta settings for fields now also field mappings.○ $this->addFieldMapping('field_body:teaser', 'teaser_source_field');○ Implemented for field handlers

via the fields() function in 2.4.○ Just provide scalar or array!

● 'More' Mapping.○ Simpler to understand.

● Still some magic.○ Files mappings still strange.○ http://drupal.org/node/1540106○ Create a destination dir for files

as tokens are iffy.Or migrate via file IDs (easier)

Implementation - __construct()Field Mapping Arguments

● More for contributed modules since Migrate 2.4 core fields have moved away from this approach.

● Used to pass multiple source fields into a single destination field (more like 'meta' information).

● As an example, a body field (with summary)$this->addFieldMapping('body', 'source_body')

->arguments(array('summary' => array('source_field' => 'teaser'),'format' => 1,

));

Implementation - __construct()Field Mapping Arguments (cont'd)

● Use the static argument function if you reuse arguments with other fields.

● Old Image Mapping Format 1:$this->addFieldMapping('image', 'source_image')

->arguments(array('source_path' => $path,'alt' => array('source_field' => 'image_alt',

));

● Old Image Mapping Format 2:$arguments = MigrateFileFieldHandler::arguments(

$path, 'file_copy', FILE_EXISTS_RENAME, NULL,array('source_field' => 'image_alt'));

$this->addFieldMapping('image', 'source_image')->arguments($arguments);

Implementation - __construct()Field Mapping Source Migrations

● When you have a value from another migration and need to look up the new ID from the migration map.○ Content Author○ References

$this->addFieldMapping('uid', 'author_id') ->sourceMigration('MyUserMigration');

● Remember to add a dependency :)○ $this->dependencies = array('MyUserMigration');

Implementation - Additional Processing

● Three ways to insert/modify the imported data mappings.○ prepareRow($row)○ prepare($entity, $row)○ complete($entity, $row)

● Each one is useful in different circumstances.

Implementation - prepareRow($row)

● Passes in the row from the current source as an object so you can make modifications.

● Can indicate that a row should be skipped during import by returning FALSE;

● Add or change field values:$row->field3 = $row->field4 .' '. $row->field5;$row->created = strtotime($row->access);$row->images = array('image1', 'image2');

Implementationprepare($entity, $row)

● Work directly with the entity object that has been populated with field mappings.○ Arguments: the entity prior to being saved, the source row.

● Final opportunity for changes before entity gets saved.● Must save fields in entity field format.● Use prepare() to populate fields that do not have a field

handler (link, relation, location as examples at time of writing)

$entity->field_link['und'][0]['value'] = 'http://drupal.org/project/migrate';

Implementationcomplete($entity, $row)

● Called after entity is saved - chance to update any *other* records that reference the current entity.

● Don't use it to save the same record again...

Implementation - Dealing with Circular Dependencies

● Implement stubs - (http://drupal.org/node/1013506)

● Specify a sourceMigration('NodeBundleMigration') on the ID's field mapping.

● Add createStub($migration, $source_key) to NodeBundleMigration which creates an empty record and returns the record ID.

● Next time NodeBundleMigration runs, it will update the stub and fill it with proper content.

Implementation - Dealing with Dynamic Migrations

● Some projects (like wordpress migrate / commerce migrate) will migrate most but not all content.

● Extend by creating destination migration.○ Same as regular migration but in __construct you

have to provide type of record and value of record.■ $this->systemOfRecord = Migration::DESTINATION■ $this->addFieldMapping('nid','nid')

->sourceMigration('NodeBundleMigration');

Implementation - Suggestions

● Separate your file migrations.○ Migrate 2.4 now has a class to migrate your files

separately.○ Can retain structure of source file directory.○ Or not (make up your own) - its just more flexible.○ Or make multiple file migrations based off your

separate content migrations and have your content migrations have a dependency on the file migration.

Migrate in other contributed modules

● Creating new types of objects?○ Write a destination handler.○ Hopefully, you can implement your object using the

entityapi and extend on the MigrateDestinationEntityAPI class.

● Create new types of fields?○ Write a field handler.

References

Projects● http://drupal.org/project/migrate● http://drupal.org/project/migrate_extrasDrupal -> Drupal Migration Sandboxes● http://drupal.org/sandbox/mikeryan/1234554● http://drupal.org/sandbox/btmash/1092900● http://drupal.org/sandbox/btmash/1492598Documentation● http://drupal.org/node/415260● http://denver2012.drupal.org/program/sessions/getting-

it-drupal-migrate● http://btmash.com/tags/migrate

Demo / Questions / Notes

Thank you :)