Transforming and mapping data

You can change data once it is loaded from an external source, via transformers and mappers.

Transformers are used to change data values, for example converting a datetime string to a DateTime object.

Mappers are used to map data to a new data structure so it is more useful for processing, for example converting an array of raw data to a collection of objects.

You can use mappers and transformers together, it's usually more useful to transform data as it's being mapped to a more useful data structure.

Example use cases are:

• Prepare data values (e.g. strip tags, decode HTML entities)

• Rename data fields (e.g. from "person_name" to "name")

• Update data values to match your local values (e.g. map the category "T-Shirts" to "casual")

• Map a single item to an object (and optionally type set item fields, e.g. to an DateTime object)

• Map a collection of items to a set of objects

We use Symfony's PropertyAccess component to help read and write data. See how to write property paths for more details.