hchokshi / silverstripe-trait-config
Merge SilverStripe configuration from traits into class configuration, while avoiding private static property conflicts.
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Type:silverstripe-vendormodule
Requires
- php: ^5.6 || ^7.0
- silverstripe/framework: ^4.0
This package is not auto-updated.
Last update: 2020-08-22 07:15:38 UTC
README
Merge SilverStripe configuration from traits into class configuration, while avoiding private static property conflicts.
Installation
-
Require composer package with
composer require hchokshi/silverstripe-trait-config
. -
Add
TraitConfigTransformer
to your config generation chain in/index.php
or/public/index.php
(4.1+).
<?php // ... $kernel = new CoreKernel(BASE_PATH); // Already there from default SilverStripe install TraitConfigTransformer::addToKernel($kernel); // Add this line
Why?
Traits provide characteristics for classes using them. By default, SilverStripe does not process YAML config from traits and
PHP limits classes from overriding properties set by traits, meaning if a trait defines a config private static
, any using
classes and their subclasses cannot define that config value except by YAML.
This package allows traits to define config by some non-conflicting name in their private static
s and map them to an actual
SilverStripe config. This module also merges trait YAML into using classes, which SilverStripe does not do by default.
SilverStripe suggests extensions to achieve the desired behaviour, but this comes with its own set of drawbacks - performance, IDE-hinting of method calls, less explicit code. While extensions are still necessary to apply code to classes from vendors etc., traits allow your own classes to be more explicit about their behaviour.
How?
Install the module as instructed under Installation
above.
Create a trait and use it in your classes. Define private static
properties as below in your trait. Both the @internal
and
@aliasConfig
annotations must be applied for this module to map a static to a different name. Don't add the @config
annotation,
as that will cause SilverStripe to pick up that property's unmapped name/value and merge it into using classes.
Trait private static properties should be named randomly or with some unique prefix so that there's no chance a using class may want to actually use a property with the same name.
Traits can define config via mapped private static
properties or via YAML using aliased names / normal unaliased names. E.g. a trait
can define db:
in YAML and it'll be merged into the config for any using classes.
While traits can also define YAML using aliased names, it is recommended to use unaliased names in YAML as there is no naming conflict and
YAML does not have the inline information about where the value will be merged like @aliasConfig
provides for private static
variables.
If a config value is defined using aliased and unaliased names, the unaliased name will be merged with a higher priority.
Example:
In the example below, MyTrait
's database columns will be merged into MyObject
.
<?php trait MyTrait { /** * @internal * @aliasConfig $db * @var array */ private static $_mytrait_db = [ // This could be called $a09sdf0asfoiasdfj - "@aliasConfig $db" is the important part // ... ]; } class MyObject extends DataObject { use MyTrait; private static $db = [ // ... ]; }
Priority:
Configuration is merged in the same way as SilverStripe's normal config system (arrays are merged, higher priority scalar values overrule arrays).
Configuration sources for a class are prioritised in the following order, from highest to lowest:
- Class config
- Class YAML
- Class private statics
- Trait config
- Trait YAML with unmapped config name (e.g.
db:
in a trait's YAML) - Trait YAML with mapped names (e.g.
jdalsfjlafdfl_db:
in a trait's YAML, where the trait has aprivate static $jdalsfjlafdfl_db
with@internal @aliasConfig $db
annotations.) - Trait private statics
- Nested trait config (e.g. if
Trait1
hasuse Trait2
,Trait2
config is merged in "Trait config" priority)