generic_transformer.md

GenericTransformer

Class behind the transformers declared in the clever_age_process.generic_transformers configuration (see Generic transformers definition). It is not a service by itself: one instance is created per declared generic transformer, and it simply applies a preconfigured chain of transformers, optionally parametrized by contextual_options.

For each entry of generic_transformers, the bundle extension (CleverAgeProcessExtension) registers a private service CleverAge\ProcessBundle\Transformer\GenericTransformer\<code>, tagged cleverage.transformer with its code (code attribute), and calls initialize(<code>, <configuration>) on it. It is then registered in the transformer registry like any other transformer, under the configured code (which must not collide with an existing transformer code: the container compilation fails), and only instantiated when used.

When the generic transformer is used, its options are the declared contextual options. The {{ option_code }} placeholders in the preconfigured transformers (keys and values, recursively) are replaced by the option values, then the resulting transformer chain is resolved and applied, as with TransformerTrait. A placeholder that is the whole string is replaced by the raw value (keeping its type, e.g. int or null); otherwise the value is inserted in the string.

Transformer reference

• Service: CleverAge\ProcessBundle\Transformer\GenericTransformer\<code> (one service per generic transformer)
• Transformer code: <code>: the key used under clever_age_process.generic_transformers

Accepted inputs

any: depends on the preconfigured transformers.

Possible outputs

any: result of the preconfigured transformer chain.

Options

The definition (clever_age_process.generic_transformers.<code>) accepts:

Code	Type	Required	Default	Description
contextual_options	array		[]	List of option code => option definition (see below); each one becomes an option of the transformer
transformers	array		[]	Transformer chain, see TransformerTrait. May contain {{ option_code }} placeholders

Each contextual option definition (~ is allowed to use all defaults) accepts:

Code	Type	Required	Default	Description
required	bool		true	The option must be provided when using the transformer (unless it has a default)
default	any		null	If not null, default value of the option
default_is_null	bool		false	Use null as default value (not possible with default)

When using the generic transformer, only its contextual options are accepted; passing transformers throws an InvalidArgumentException.

Examples

• Definition without option, and usage

# Bundle configuration level (config/packages/*.yaml)
clever_age_process:
  generic_transformers:
    uppercase:
      transformers:
        callback:
          callback: strtoupper

# Transformer options level
uppercase: ~

• Definition with contextual options, and usage: substr($value, 2, null)

# Bundle configuration level (config/packages/*.yaml)
clever_age_process:
  generic_transformers:
    substr:
      contextual_options:
        offset:
          required: true
        length:
          default_is_null: true
      transformers:
        callback:
          callback: substr
          right_parameters: ['{{ offset }}', '{{ length }}']

# Transformer options level
substr:
  offset: 2

Notes

• Contextual options are transformer options, unrelated to the process context (-c key:value).
• An option declared with required: false and no default may be omitted: its placeholders are then replaced by null.