and let’s assume the following content of Bar.php:
// Bar.phpnamespaceOtherDir;useSomeDir\Foo;// This now conflicts the class OtherDir\Foo
If both files OtherDir/Foo.php and SomeDir/Foo.php are loaded in the
same runtime, you will see a PHP error such as the following:
PHP Fatal error: Cannot use SomeDir\Foo as Foo because the name is already in use in OtherDir/Foo.php
However, as OtherDir/Foo.php does not necessarily have to be loaded and the
error is only triggered if it is loaded before OtherDir/Bar.php, this problem
might go unnoticed for a while. In order to prevent this error from surfacing,
you must import the namespace with a different alias:
// Bar.phpnamespaceOtherDir;useSomeDir\FooasSomeDirFoo;// There is no conflict anymore.
The return type of return new \BlogTest\PostType(); (BlogTest\PostType) is incompatible with the return type declared by the interface Youshido\GraphQL\Field\FieldInterface::getType of type Youshido\GraphQL\Type\AbstractType.
If you return a value from a function or method, it should be a sub-type of the
type that is given by the parent type f.e. an interface, or abstract method.
This is more formally defined by the
Lizkov substitution principle,
and guarantees that classes that depend on the parent type can use any instance
of a child type interchangably. This principle also belongs to the
SOLID principles
for object oriented design.
Our function my_function expects a Post object, and outputs the author
of the post. The base class Post returns a simple string and outputting a
simple string will work just fine. However, the child class BlogPost which
is a sub-type of Post instead decided to return an object, and is
therefore violating the SOLID principles. If a BlogPost were passed to
my_function, PHP would not complain, but ultimately fail when executing the
strtoupper call in its body.
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21
}
22
23
public function resolve($value, array $args, ResolveInfo $info)
24
{
25
return [
26
"title" => "New approach in API has been revealed",
27
"summary" => "This post describes a new approach to create and maintain APIs",
Youshido /
GraphQL
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Let’s assume that you have a directory layout like this:
. |-- OtherDir | |-- Bar.php | `-- Foo.php `-- SomeDir `-- Foo.phpand let’s assume the following content of
Bar.php:If both files
OtherDir/Foo.phpandSomeDir/Foo.phpare loaded in the same runtime, you will see a PHP error such as the following:PHP Fatal error: Cannot use SomeDir\Foo as Foo because the name is already in use in OtherDir/Foo.phpHowever, as
OtherDir/Foo.phpdoes not necessarily have to be loaded and the error is only triggered if it is loaded beforeOtherDir/Bar.php, this problem might go unnoticed for a while. In order to prevent this error from surfacing, you must import the namespace with a different alias: