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Here's a snippet of some Drupal code that I wrote last week. It's responsible for converting an array of nodes into a Collection of one of it's field values.<\/p>\n\n

return Collection::make($stationNodes)\n  ->map(fn (NodeInterface $station): string => $station->get('field_station_code')->getString())\n  ->values();\n<\/code><\/pre>\n\n
There are two issues with this code.<\/p>\n\n
First, whilst I'm implicitly saying that it accepts a certain type of node, because of the NodeInterface<\/code> typehint this could accept any type of node. If that node doesn't have the required field, the code will error - but I'd like to know sooner if an incorrect type of node is passed and make it explicit that only a certain type of node can be used.<\/p>\n\n
Second, the code for getting the field values is quite verbose and is potentially repeated in other places within the codebase. I'd like to have a simple way to access these field values that I can reuse anywhere else. If the logic for getting these particular field values changes, then I'd only need to change it in one place.<\/p>\n\n
Introducing a value object<\/h2>\n\n
This is the value object that I created.<\/p>\n\n
It accepts the original node but checks to ensure that the node is the correct type. If not, an Exception is thrown.<\/p>\n\n
I've added a helper method to get the field value, encapsulating that logic in a reusable function whilst making the code easier to read and its intent clearer.<\/p>\n\n
namespace Drupal\\mymodule\\ValueObject;\n\nuse Drupal\\node\\NodeInterface;\n\nfinal class Station implements StationInterface {\n\n  private NodeInterface $node;\n\n  private function __construct(NodeInterface $node) {\n    if ($node->bundle() != 'station') {\n      throw new \\InvalidArgumentException();\n    }\n\n    $this->node = $node;\n  }\n\n  public function getStationCode(): string {\n    return $this->node->get('field_station_code')->getString();\n  }\n\n  public static function fromNode(NodeInterface $node): self {\n    return new self($node);\n  }\n\n}\n<\/code><\/pre>\n\n
Refactoring to use the value object<\/h2>\n\n
This is what my code now looks like:<\/p>\n\n
return Collection::make($stationNodes)\n  ->map(fn (NodeInterface $node): StationInterface => Station::fromNode($node))\n  ->map(fn (StationInterface $station): string => $station->getStationCode())\n  ->values();\n<\/code><\/pre>\n\n
<<<<<<< HEAD:website\/source\/_daily_emails\/2022-10-03.md<\/h1>\n\n
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b9cea6d (chore: replace Sculpin with Astro):website\/src\/pages\/daily-emails\/2022-10-03.md\n              I've added an additional map<\/code> to convert the nodes to the value object, but the second map can now use the new typehint - ensuring better type safety and also giving us auto-completion in IDEs and text editors. If an incorrect node type is passed in, then the Exception will be thrown and a much clearer error message will be shown.<\/p>\n            <\/blockquote>\n          <\/blockquote>\n        <\/blockquote>\n      <\/blockquote>\n    <\/blockquote>\n  <\/blockquote>\n<\/blockquote>\n\n
Finally, I can use the helper method to get the field value, encapsulating the logic within the value object and making it intention clearer and easier to read.<\/p>\n\n        ",
            "format": "full_html",
            "processed": "\n          
Here's a snippet of some Drupal code that I wrote last week. It's responsible for converting an array of nodes into a Collection of one of it's field values.<\/p>\n\n
return Collection::make($stationNodes)\n  ->map(fn (NodeInterface $station): string => $station->get('field_station_code')->getString())\n  ->values();\n<\/code><\/pre>\n\n
There are two issues with this code.<\/p>\n\n
First, whilst I'm implicitly saying that it accepts a certain type of node, because of the NodeInterface<\/code> typehint this could accept any type of node. If that node doesn't have the required field, the code will error - but I'd like to know sooner if an incorrect type of node is passed and make it explicit that only a certain type of node can be used.<\/p>\n\n
Second, the code for getting the field values is quite verbose and is potentially repeated in other places within the codebase. I'd like to have a simple way to access these field values that I can reuse anywhere else. If the logic for getting these particular field values changes, then I'd only need to change it in one place.<\/p>\n\n
Introducing a value object<\/h2>\n\n
This is the value object that I created.<\/p>\n\n
It accepts the original node but checks to ensure that the node is the correct type. If not, an Exception is thrown.<\/p>\n\n
I've added a helper method to get the field value, encapsulating that logic in a reusable function whilst making the code easier to read and its intent clearer.<\/p>\n\n
namespace Drupal\\mymodule\\ValueObject;\n\nuse Drupal\\node\\NodeInterface;\n\nfinal class Station implements StationInterface {\n\n  private NodeInterface $node;\n\n  private function __construct(NodeInterface $node) {\n    if ($node->bundle() != 'station') {\n      throw new \\InvalidArgumentException();\n    }\n\n    $this->node = $node;\n  }\n\n  public function getStationCode(): string {\n    return $this->node->get('field_station_code')->getString();\n  }\n\n  public static function fromNode(NodeInterface $node): self {\n    return new self($node);\n  }\n\n}\n<\/code><\/pre>\n\n
Refactoring to use the value object<\/h2>\n\n
This is what my code now looks like:<\/p>\n\n
return Collection::make($stationNodes)\n  ->map(fn (NodeInterface $node): StationInterface => Station::fromNode($node))\n  ->map(fn (StationInterface $station): string => $station->getStationCode())\n  ->values();\n<\/code><\/pre>\n\n
<<<<<<< HEAD:website\/source\/_daily_emails\/2022-10-03.md<\/h1>\n\n
\n  
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\n      
\n        
\n          
\n            
\n              
b9cea6d (chore: replace Sculpin with Astro):website\/src\/pages\/daily-emails\/2022-10-03.md\n              I've added an additional map<\/code> to convert the nodes to the value object, but the second map can now use the new typehint - ensuring better type safety and also giving us auto-completion in IDEs and text editors. If an incorrect node type is passed in, then the Exception will be thrown and a much clearer error message will be shown.<\/p>\n            <\/blockquote>\n          <\/blockquote>\n        <\/blockquote>\n      <\/blockquote>\n    <\/blockquote>\n  <\/blockquote>\n<\/blockquote>\n\n
Finally, I can use the helper method to get the field value, encapsulating the logic within the value object and making it intention clearer and easier to read.<\/p>\n\n        ",
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