fix(metadata): relax the XML schema where it rejects valid metadata

src/Metadata/Extractor/ResourceExtractorTrait.php

@@ -80,7 +80,7 @@ private function phpize(\SimpleXMLElement|array|null $resource, string $key, str
 
     private function buildArgs(\SimpleXMLElement $resource): ?array
     {
-        if (!isset($resource->args->arg)) {
+        if (!isset($resource->args)) {
             return null;
         }
 

src/Metadata/Extractor/XmlResourceExtractor.php

@@ -509,8 +509,8 @@ private function buildLinks(\SimpleXMLElement $resource): ?array
         }
 
         $links = [];
-        foreach ($resource->links as $link) {
-            $links[] = new Link(rel: (string) $link->link->attributes()->rel, href: (string) $link->link->attributes()->href);
+        foreach ($resource->links->link as $link) {
+            $links[] = new Link(rel: (string) $link->attributes()->rel, href: (string) $link->attributes()->href);
         }
 
         return $links;
@@ -526,8 +526,8 @@ private function buildHeaders(\SimpleXMLElement $resource): ?array
         }
 
         $headers = [];
-        foreach ($resource->headers as $header) {
-            $headers[(string) $header->header->attributes()->key] = (string) $header->header->attributes()->value;
+        foreach ($resource->headers->header as $header) {
+            $headers[(string) $header->attributes()->key] = (string) $header->attributes()->value;
         }
 
         return $headers;

src/Metadata/Extractor/schema/resources.xsd

@@ -23,6 +23,7 @@
         <xsd:attributeGroup ref="extendedBase"/>
         <xsd:attribute type="xsd:string" name="uriTemplate"/>
         <xsd:attribute type="xsd:string" name="class" use="required"/>
+        <xsd:attribute type="xsd:boolean" name="openapi"/>
     </xsd:complexType>
 
     <xsd:complexType name="operations">
@@ -45,7 +46,7 @@
         <xsd:attribute type="xsd:boolean" name="write"/>
         <xsd:attribute type="xsd:boolean" name="serialize"/>
         <xsd:attribute type="xsd:boolean" name="openapi"/>
-        <xsd:attribute type="xsd:positiveInteger" name="priority"/>
+        <xsd:attribute type="xsd:integer" name="priority"/>
         <xsd:attribute type="xsd:integer" name="routePriority"/>
         <xsd:attribute type="xsd:string" name="name"/>
         <xsd:attribute type="xsd:string" name="itemUriTemplate"/>
@@ -73,14 +74,14 @@
         <xsd:attribute type="xsd:boolean" name="validate"/>
         <xsd:attribute type="xsd:boolean" name="write"/>
         <xsd:attribute type="xsd:boolean" name="serialize"/>
-        <xsd:attribute type="xsd:positiveInteger" name="priority"/>
+        <xsd:attribute type="xsd:integer" name="priority"/>
         <xsd:attribute type="xsd:integer" name="routePriority"/>
         <xsd:attribute type="xsd:string" name="name"/>
     </xsd:complexType>
 
     <xsd:complexType name="args">
-        <xsd:sequence maxOccurs="unbounded">
-            <xsd:element name="arg" maxOccurs="unbounded" type="arg"/>
+        <xsd:sequence>
+            <xsd:element name="arg" minOccurs="0" maxOccurs="unbounded" type="arg"/>
         </xsd:sequence>
     </xsd:complexType>
 
@@ -420,7 +421,7 @@
 
     <xsd:complexType name="links">
         <xsd:sequence>
-            <xsd:element ref="link"/>
+            <xsd:element ref="link" maxOccurs="unbounded"/>
         </xsd:sequence>
     </xsd:complexType>
 
@@ -433,7 +434,7 @@
 
     <xsd:complexType name="headers">
         <xsd:sequence>
-            <xsd:element ref="header"/>
+            <xsd:element ref="header" maxOccurs="unbounded"/>
         </xsd:sequence>
     </xsd:complexType>
 
@@ -513,8 +514,8 @@
         <xsd:attribute type="xsd:boolean" name="paginationEnabled"/>
         <xsd:attribute type="xsd:boolean" name="paginationFetchJoinCollection"/>
         <xsd:attribute type="xsd:boolean" name="paginationUseOutputWalkers"/>
-        <xsd:attribute type="xsd:positiveInteger" name="paginationItemsPerPage"/>
-        <xsd:attribute type="xsd:positiveInteger" name="paginationMaximumItemsPerPage"/>
+        <xsd:attribute type="xsd:nonNegativeInteger" name="paginationItemsPerPage"/>
+        <xsd:attribute type="xsd:nonNegativeInteger" name="paginationMaximumItemsPerPage"/>
         <xsd:attribute type="xsd:boolean" name="paginationPartial"/>
         <xsd:attribute type="xsd:string" name="paginationType"/>
         <xsd:attribute type="xsd:string" name="processor"/>

src/Metadata/Tests/Extractor/XmlExtractorTest.php

@@ -478,6 +478,18 @@ public static function getInvalidPaths(): array
         ];
     }
 
+    public function testLessStrictSchema(): void
+    {
+        $resource = (new XmlResourceExtractor([__DIR__.'/xml/less_strict_schema.xml']))->getResources()[Comment::class][0];
+
+        $this->assertFalse($resource['openapi']);
+        $this->assertSame(0, $resource['paginationItemsPerPage']);
+        $this->assertSame(['https://example.com/a', 'https://example.com/b'], array_map(static fn ($link) => $link->getHref(), $resource['links']));
+        $this->assertSame(['X-A' => 'a', 'X-B' => 'b'], $resource['headers']);
+        $this->assertSame(-1, $resource['operations'][0]['priority']);
+        $this->assertSame([], $resource['graphQlOperations'][0]['args']);
+    }
+
     /**
      * Tests issue #8175: two XML operations sharing an explicit name silently
      * dropped one another. The factory must reject the duplicate up front.

src/Metadata/Tests/Extractor/xml/less_strict_schema.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+
+<resources xmlns="https://api-platform.com/schema/metadata/resources-3.0"
+           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+           xsi:schemaLocation="https://api-platform.com/schema/metadata/resources-3.0
+           https://api-platform.com/schema/metadata/resources-3.0.xsd">
+    <resource class="ApiPlatform\Metadata\Tests\Fixtures\ApiResource\Comment" openapi="false" paginationItemsPerPage="0">
+        <links>
+            <link rel="a" href="https://example.com/a"/>
+            <link rel="b" href="https://example.com/b"/>
+        </links>
+        <headers>
+            <header key="X-A" value="a"/>
+            <header key="X-B" value="b"/>
+        </headers>
+        <operations>
+            <operation class="ApiPlatform\Metadata\Get" priority="-1"/>
+        </operations>
+        <graphQlOperations>
+            <graphQlOperation class="ApiPlatform\Metadata\GraphQl\Query" name="notRetrievedQuery">
+                <args/>
+            </graphQlOperation>
+        </graphQlOperations>
+    </resource>
+</resources>