为什么laravel渴望加载约束不起作用？

Question

我有这个作为我想要做的基本但是约束不适用

$this['subs'] = Cat::with([
    'children' => function($query) {
        $query -> where('parent_id', 0);
    }
]) -> get();

Answer 1

你正在寻找的是whereHas，像这样：

$this['subs'] = Cat::whereHas('children', function ($query) {
                  $query->where('parent_id',0);
               })->get();

在with中查询只是查询它查询的关系，而不是记录集cat本身。

Answer 2

你有一只id = 0的猫吗？

尝试：

Cat::with('children')->find(0)

假设你有一只id = 0的猫;这将返回id = 0的猫及其子节点（如果有的话）。

要么：

Cat::has('children')->get()

这将返回所有有孩子的猫。

要么：

Cat::with('children')->get()

这将返回所有猫及其子女，如果有的话

Answer 3

你正在使用October CMS所以你可以使用traits nested-tree

docs：https://octobercms.com/docs/database/traits#nested-tree

class Cat extends Model
{
    use \October\Rain\Database\Traits\NestedTree;
}

现在

$model = Cat::where('slug', $param_slug)->first();

然后

$model->getEagerRoot(); // Returns a list of all root nodes, with ->children eager loaded.
// OR
$model->getEagerChildren(); // Returns direct child nodes, with ->children eager loaded.

你可以有ton of options

https://github.com/octobercms/library/blob/master/src/Database/Traits/NestedTree.php

/* General access methods:
 *
 *   $model->getRoot(); // Returns the highest parent of a node.
 *   $model->getRootList(); // Returns an indented array of key and value columns from root.
 *   $model->getParent(); // The direct parent node.
 *   $model->getParents(); // Returns all parents up the tree.
 *   $model->getParentsAndSelf(); // Returns all parents up the tree and self.
 *   $model->getChildren(); // Set of all direct child nodes.
 *   $model->getSiblings(); // Return all siblings (parent's children).
 *   $model->getSiblingsAndSelf(); // Return all siblings and self.
 *   $model->getLeaves(); // Returns all final nodes without children.
 *   $model->getDepth(); // Returns the depth of a current node.
 *   $model->getChildCount(); // Returns number of all children.
 *
 * Query builder methods:
 *
 *   $query->withoutNode(); // Filters a specific node from the results.
 *   $query->withoutSelf(); // Filters current node from the results.
 *   $query->withoutRoot(); // Filters root from the results.
 *   $query->children(); // Filters as direct children down the tree.
 *   $query->allChildren(); // Filters as all children down the tree.
 *   $query->parent(); // Filters as direct parent up the tree.
 *   $query->parents(); // Filters as all parents up the tree.
 *   $query->siblings(); // Filters as all siblings (parent's children).
 *   $query->leaves(); // Filters as all final nodes without children.
 *   $query->getNested(); // Returns an eager loaded collection of results.
 *   $query->listsNested(); // Returns an indented array of key and value columns.
 *
 * Flat result access methods:
 *
 *   $model->getAll(); // Returns everything in correct order.
 *   $model->getAllRoot(); // Returns all root nodes.
 *   $model->getAllChildren(); // Returns all children down the tree.
 *   $model->getAllChildrenAndSelf(); // Returns all children and self.
 *
 * Eager loaded access methods:
 *
 *   $model->getEagerRoot(); // Returns a list of all root nodes, with ->children eager loaded.
 *   $model->getEagerChildren(); // Returns direct child nodes, with ->children eager loaded.
 *
 */

请查看它为父母和孩子关系提供的真正快捷方便的方式。

如果有任何疑问请评论。