Documentation

This method is called when is called to transform the requests tainted data into an acceptable format.

The same transformers are called in the reverse order so the responsibility is to return one of the types that would be expected as input of transform().

This method must be able to deal with empty values. Usually this will be an empty string, but depending on your implementation other empty values are possible as well (such as NULL). The reasoning behind this is that value transformers must be chainable. If the reverseTransform() method of the first value transformer outputs an empty string, the second value transformer must be able to process that value.

By convention, reverseTransform() should return NULL if an empty string is passed.

This method is called when the form field is initialized with its default data, on two occasions for two types of transformers:

1. Model transformers which normalize the model data. This is mainly useful when the same form type (the same configuration) has to handle different kind of underlying data, e.g The DateType can deal with strings or \DateTime objects as input.

2. View transformers which adapt the normalized data to the view format. a/ When the form is simple, the value returned by convention is used directly in the view and thus can only be a string or an array. In this case the data class should be null.

   b/ When the form is compound the returned value should be an array or an object to be mapped to the children. Each property of the compound data will be used as model data by each child and will be transformed too. In this case data class should be the class of the object, or null when it is an array.

All transformers are called in a configured order from model data to view value. At the end of this chain the view data will be validated against the data class setting.

This method must be able to deal with empty values. Usually this will be NULL, but depending on your implementation other empty values are possible as well (such as empty strings). The reasoning behind this is that data transformers must be chainable. If the transform() method of the first data transformer outputs NULL, the second must be able to process that value.