Add an optional default value for SelectFormField

com.woltlab.wcf/templates/shared_selectFormField.tpl

@@ -8,7 +8,9 @@
 		required
 	{/if}
 >
-	<option value="">{lang}wcf.global.noSelection{/lang}</option>
+	{if !$field->hasDefaultValue()}
+		<option value="">{lang}wcf.global.noSelection{/lang}</option>
+	{/if}
 	{foreach from=$field->getNestedOptions() item=__fieldNestedOption}
 		<option
 			value="{$__fieldNestedOption[value]}"

wcfsetup/install/files/lib/system/form/builder/field/SelectFormField.class.php

@@ -36,6 +36,11 @@ final class SelectFormField extends AbstractFormField implements
      */
     private bool $ignoreInvalidValues = false;
 
+    /**
+     * @since 6.2
+     */
+    private ?string $defaultValue = null;
+
     /**
      * @inheritDoc
      */
@@ -102,4 +107,43 @@ public function ignoreInvalidValues(bool $ignoreInvalidValues = true): self
 
         return $this;
     }
+
+    /**
+     * Sets an initial default value.
+     *
+     * The provided value must be among the existing values, setting it to
+     * `null` disables this feature. When a default value is present the default
+     * option “No Selection” becomes unavailable.
+     *
+     * @since 6.2
+     */
+    public function defaultValue(?string $defaultValue = null): self
+    {
+        if ($defaultValue !== null && !isset($this->getOptions()[$defaultValue])) {
+            throw new \InvalidArgumentException("Unknown default value '{$defaultValue}' for field '{$this->getId()}'.");
+        }
+
+        $this->defaultValue = $defaultValue;
+
+        return $this;
+    }
+
+    /**
+     * @since 6.2
+     */
+    public function hasDefaultValue(): bool
+    {
+        return $this->defaultValue !== null;
+    }
+
+    #[\Override]
+    public function getValue()
+    {
+        $value = parent::getValue();
+        if ($value === null && $this->defaultValue !== null) {
+            return $this->defaultValue;
+        }
+
+        return $value;
+    }
 }