Laravel nova，“在 null 上调用函数 tap()”

Question

• Laravel 版本：8.12
• Nova 版本：3.22.0
• PHP 版本：7.4.2
• 网络服务器artisan serve

感觉就像我错过了 Laravel Nova 中必不可少的东西。 我有两个模型，我希望它们作为 Nova 资源，它们之间有关系。它们的模型称为“模板”和“资产”，其中一个“模板”有许多“资产”。

模型中没有逻辑，只有两个简单的模型，带有文本字段等简单资源。

当我查看或编辑模板时，我得到：

"message": "Call to a member function tap() on null",
    "exception": "Error",
    "file": "laravel\\nova\\src\\Query\\Builder.php",
    "line": 265,

它看起来像这样： 我试过了：

• 重新创建具有不同名称的模型和资产。
• 我在php artisan clear:cache 和composer dump 之间每次更改。
• 我创建了一个新模型 + 资源，并改为附加到用户模型/资源，效果与预期一致。所以我将用户与模板进行了比较，但我没有发现任何不同（除了用户是可验证的）
• 删除并重新安装了供应商文件夹。
• 清除所有未使用的代码

模板模型（Models/Template.php）：

<?php
namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Template extends Model
{
    use HasFactory;
    protected $casts = [
        'published_at' => 'datetime',
    ];

    public function assets() {        
        $this->hasMany(Asset::class);
    }
}

模板资源（Nova/Template.php）：

<?php

namespace App\Nova;

use Illuminate\Http\Request;
use Laravel\Nova\Fields\ID;
use Laravel\Nova\Http\Requests\NovaRequest;
use Laravel\Nova\Fields\Text;
//use Laravel\Nova\Fields\Image;
use Laravel\Nova\Fields\DateTime;
use Laravel\Nova\Fields\HasMany;

class Template extends Resource
{
    public static $model = \App\Models\Template::class;

    public static $title = 'title';

    public static $search = [
        'title',
    ];

    public function fields(Request $request)
    {
        return [
            ID::make()->sortable(),
            Text::make('Title'),
            Text::make('Slug'),
            Text::make('Content'),
            //Image::make(__('Featured Image')),
            DateTime::make('Will be published at', "published_at")->format("YYYY-MM-DD HH:MM:SS"),
            Text::make('Source'),
            Text::make('Composition'),
            HasMany::make('Assets')
        ];
    }

    public function cards(Request $request){
        return [];
    }

    public function filters(Request $request){
        return [];
    }

    public function lenses(Request $request){
        return [];
    }
    public function actions(Request $request){
        return [];
    }
}

资产模型（Models/Asset.php）：

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Asset extends Model
{
    public function template() {
        return $this->belongsTo(Template::class);
    }
}

以及资产资源（Noca/Asset.php）：

<?php

namespace App\Nova;

use Illuminate\Http\Request;
use Laravel\Nova\Fields\ID;
use Laravel\Nova\Http\Requests\NovaRequest;
use Laravel\Nova\Fields\Text;
use Laravel\Nova\Fields\BelongsTo;

class Asset extends Resource
{

    public static $model = \App\Models\Asset::class;

    public static $title = 'id';

    public static $search = [
        'id',
    ];


    public function fields(Request $request)
    {
        return [
            ID::make()->sortable(),
            Text::make('Property', 'property'),
            Text::make('Value', 'value'),
            BelongsTo::make('Template')
        ];
    }

    public function cards(Request $request){
        return [];
    }

    public function filters(Request $request){
        return [];
    }

    public function lenses(Request $request){
        return [];
    }

    public function actions(Request $request){
        return [];
    }
}

但我仍然遇到同样的错误。我很快就要发疯了，为此我投入了很多时间。

我错过了什么？

完整的跟踪：

"trace": [
        {
            "file": "D:\\kod\\project\\laravel\\nova\\src\\Query\\Builder.php",
            "line": 196,
            "function": "applyQueryCallbacks",
            "class": "Laravel\\Nova\\Query\\Builder",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\nova\\src\\Http\\Requests\\ResourceIndexRequest.php",
            "line": 30,
            "function": "paginate",
            "class": "Laravel\\Nova\\Query\\Builder",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\nova\\src\\Http\\Controllers\\ResourceIndexController.php",
            "line": 20,
            "function": "searchIndex",
            "class": "Laravel\\Nova\\Http\\Requests\\ResourceIndexRequest",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Routing\\Controller.php",
            "line": 54,
            "function": "handle",
            "class": "Laravel\\Nova\\Http\\Controllers\\ResourceIndexController",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Routing\\ControllerDispatcher.php",
            "line": 45,
            "function": "callAction",
            "class": "Illuminate\\Routing\\Controller",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Routing\\Route.php",
            "line": 254,
            "function": "dispatch",
            "class": "Illuminate\\Routing\\ControllerDispatcher",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Routing\\Route.php",
            "line": 197,
            "function": "runController",
            "class": "Illuminate\\Routing\\Route",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Routing\\Router.php",
            "line": 693,
            "function": "run",
            "class": "Illuminate\\Routing\\Route",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 128,
            "function": "Illuminate\\Routing\\{closure}",
            "class": "Illuminate\\Routing\\Router",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\nova\\src\\Http\\Middleware\\Authorize.php",
            "line": 18,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Laravel\\Nova\\Http\\Middleware\\Authorize",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\nova\\src\\Http\\Middleware\\BootTools.php",
            "line": 20,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Laravel\\Nova\\Http\\Middleware\\BootTools",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\nova\\src\\Http\\Middleware\\DispatchServingNovaEvent.php",
            "line": 20,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Laravel\\Nova\\Http\\Middleware\\DispatchServingNovaEvent",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Routing\\Middleware\\SubstituteBindings.php",
            "line": 50,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Illuminate\\Routing\\Middleware\\SubstituteBindings",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Auth\\Middleware\\Authenticate.php",
            "line": 44,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\nova\\src\\Http\\Middleware\\Authenticate.php",
            "line": 31,
            "function": "handle",
            "class": "Illuminate\\Auth\\Middleware\\Authenticate",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Laravel\\Nova\\Http\\Middleware\\Authenticate",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Foundation\\Http\\Middleware\\VerifyCsrfToken.php",
            "line": 78,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Illuminate\\Foundation\\Http\\Middleware\\VerifyCsrfToken",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\View\\Middleware\\ShareErrorsFromSession.php",
            "line": 49,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Illuminate\\View\\Middleware\\ShareErrorsFromSession",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Session\\Middleware\\StartSession.php",
            "line": 121,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Session\\Middleware\\StartSession.php",
            "line": 64,
            "function": "handleStatefulRequest",
            "class": "Illuminate\\Session\\Middleware\\StartSession",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Illuminate\\Session\\Middleware\\StartSession",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Cookie\\Middleware\\AddQueuedCookiesToResponse.php",
            "line": 37,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Illuminate\\Cookie\\Middleware\\AddQueuedCookiesToResponse",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Cookie\\Middleware\\EncryptCookies.php",
            "line": 67,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Illuminate\\Cookie\\Middleware\\EncryptCookies",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 103,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Routing\\Router.php",
            "line": 695,
            "function": "then",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Routing\\Router.php",
            "line": 670,
            "function": "runRouteWithinStack",
            "class": "Illuminate\\Routing\\Router",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Routing\\Router.php",
            "line": 636,
            "function": "runRoute",
            "class": "Illuminate\\Routing\\Router",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Routing\\Router.php",
            "line": 625,
            "function": "dispatchToRoute",
            "class": "Illuminate\\Routing\\Router",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Foundation\\Http\\Kernel.php",
            "line": 166,
            "function": "dispatch",
            "class": "Illuminate\\Routing\\Router",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 128,
            "function": "Illuminate\\Foundation\\Http\\{closure}",
            "class": "Illuminate\\Foundation\\Http\\Kernel",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\nova\\src\\Http\\Middleware\\ServeNova.php",
            "line": 27,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Laravel\\Nova\\Http\\Middleware\\ServeNova",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Foundation\\Http\\Middleware\\TransformsRequest.php",
            "line": 21,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Illuminate\\Foundation\\Http\\Middleware\\TransformsRequest",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Foundation\\Http\\Middleware\\TransformsRequest.php",
            "line": 21,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Illuminate\\Foundation\\Http\\Middleware\\TransformsRequest",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Foundation\\Http\\Middleware\\ValidatePostSize.php",
            "line": 27,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Illuminate\\Foundation\\Http\\Middleware\\ValidatePostSize",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Foundation\\Http\\Middleware\\PreventRequestsDuringMaintenance.php",
            "line": 86,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Illuminate\\Foundation\\Http\\Middleware\\PreventRequestsDuringMaintenance",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\fruitcake\\laravel-cors\\src\\HandleCors.php",
            "line": 37,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Fruitcake\\Cors\\HandleCors",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\fideloper\\proxy\\src\\TrustProxies.php",
            "line": 57,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 167,
            "function": "handle",
            "class": "Fideloper\\Proxy\\TrustProxies",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Pipeline\\Pipeline.php",
            "line": 103,
            "function": "Illuminate\\Pipeline\\{closure}",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Foundation\\Http\\Kernel.php",
            "line": 141,
            "function": "then",
            "class": "Illuminate\\Pipeline\\Pipeline",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\vendor\\laravel\\framework\\src\\Illuminate\\Foundation\\Http\\Kernel.php",
            "line": 110,
            "function": "sendRequestThroughRouter",
            "class": "Illuminate\\Foundation\\Http\\Kernel",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\public\\index.php",
            "line": 52,
            "function": "handle",
            "class": "Illuminate\\Foundation\\Http\\Kernel",
            "type": "->"
        },
        {
            "file": "D:\\kod\\project\\laravel\\server.php",
            "line": 21,
            "function": "require_once"
        }
    ]

Answer 1

这太简单了，我忘了从模板模型中返回 hasMany 关系。

    public function assets() {        
        $this->hasMany(Asset::class);
    }

应该是：

    public function assets() {        
        return $this->hasMany(Asset::class);
    }