transformers.md

description	Transformers mutate a single piece of data within a Recipe.

Transformers

Transformers are used by Recipes to mutate data between the source and target connectors. A transformation might be a simple as copying a value, or completely custom behaviour using callbacks.

Transformers implement the \HelloPablo\DataMigration\Interfaces\Transformer trait.

Bundled Transformers

The following transformers are bundled with the module:

Copy

This transformer performs no mutations, simply copying the value from source_col to target_col exatly as it appears:

yield new \HelloPablo\DataMigration\Transformer\Copy(
    'source_col',
    'target_col'
);

Set

No source column is expected, returns the value as specified as the third argument:

yield new \HelloPablo\DataMigration\Transformer\Set(
    null,
    'target_col',
    'value'
);

Callback

Passes the source value to a callback function which returns the new value.

yield new \HelloPablo\DataMigration\Transformer\Callback(
    'source_col',
    'target_col',
    function($mInput, $oUnit) {
        /**
         * Mutates $mInput, can inspect $oUnit if necessary
         */
         return $mInput * 100;
    )
);

Date

Parses a value as a date and returns a formatted date string, pass a default value as the third parameter (used if col_a is an invalid value).

yield new \HelloPablo\DataMigration\Transformer\Date(
    'source_col',
    'target_col',
    new \DateTime()
);

{% hint style="info" %} Defaults to Y-m-d, change this using the setFormat method. {% endhint %}

DateTime

As Date but includes a time component.

Id

Maps an old ID to a new ID, understand more about how this works in ID Tracking.

yield new \HelloPablo\DataMigration\Transformer\Id(
    'source_col',
    'target_col',
    \App\Pipeline\Book::class
);

Merge

Merges multiple source columns into a single value using glue.

yield new \HelloPablo\DataMigration\Transformer\Merge(
    'source_col',
    'target_col',
    ['another_source_col']
);

The above would result in the values of source_col and another_source_col being concactenated using a space.

Slug

Generates a value sutiable for a URL from a source_col:

yield new \HelloPablo\DataMigration\Transformer\Slug(
    'source_col',
    'target_col'
);

StripHtml

Removes all HTML from a string:

yield new \HelloPablo\DataMigration\Transformer\StripHtml(
    'source_col',
    'target_col'
);

Trim

Trims whitespace from a string:

yield new \HelloPablo\DataMigration\Transformer\Trim(
    'source_col',
    'target_col'
);

Truncate

Truncates a string to a maximum length:

yield new \HelloPablo\DataMigration\Transformer\Truncate(
    'source_col',
    'target_col'
    // $iMaxLength, maximum length of string, defaults to 150
    // $sEllipsis, string to use for the ellipsis, defaults to ...
);

Grouping Transformers

Each target property must be represented by a single Transformer. In roder to perform a series of transformations on a property you must use the Group transformer:

yield new \HelloPablo\DataMigration\Transformer\Group(
    'source_col',
    'target_col',
    [
        new \HelloPablo\DataMigration\Transformer\StripHtml(),
        new \HelloPablo\DataMigration\Transformer\Truncate()
    ]
);

{% hint style="info" %} Note that we supply an array of transfromer instances, and we do not specify any column data outside of the Group transformer. {% endhint %}