Create new Post with default Category belongsToMany - laravel

Question

I have a Post/Category manyToMany relations and would like to be able to attach a default category named "Uncategorised" to each new post that is created. How can I do that? A BelongsToMany method only works on the Details page, not on Create page.
BelongsToMany::make(__('Categories'), 'categories', Category::class),

Answer 1

You can also set default value to your database field so that you can omit passing category and will be taken default to Uncategorised like if you are using MySQL you can do it this way by creating migration
$table->text('category')->default(0);

Answer 2

Because the BelongsToMany not show on mode create in Post Nova model. So we have to make our custom Select, by add this code to your fields:
public function fields(Request $request)
{
if($request->editMode=="create"){
$categories = \App\Category::get(['id','name']);
$options = [];
foreach($categories as $value){
$options[$value->id] = $value->name;
}
return [
ID::make()->sortable(),
Text::make('Title'),
Text::make('Summary'),
Textarea::make('Content'),
Select::make('Categories', 'category_id')
->options($options)
->displayUsingLabels()
->withMeta(['value' => 1]) // 1 = id of Uncategorised in categories table
];
}
return [
ID::make()->sortable(),
Text::make('Title'),
Text::make('Summary'),
Textarea::make('Content'),
BelongsToMany::make('Categories','categories')->display('name'),
];
}
Don’t forget relationship function in both, Post and Category model:
class Post extends Model
{
public function categories(){
return $this->belongsToMany(Category::class, 'category_post', 'post_id', 'category_id');
}
}
And:
class Category extends Model
{
public function posts(){
return $this->belongsToMany(Post::class,'category_post', 'category_id', 'post_id');
}
}
Then, custom the function process the data on mode Create of Post resource page, it’s at nova\src\Http\Controllers\ResourceStoreController.php, change function handle to this:
public function handle(CreateResourceRequest $request)
{
$resource = $request->resource();
$resource::authorizeToCreate($request);
$resource::validateForCreation($request);
$model = DB::transaction(function () use ($request, $resource) {
[$model, $callbacks] = $resource::fill(
$request, $resource::newModel()
);
if ($request->viaRelationship()) {
$request->findParentModelOrFail()
->{$request->viaRelationship}()
->save($model);
} else {
$model->save();
// your code to save to pivot category_post here
if(isset($request->category_id)&&($resource=='App\Nova\Post')){
$category_id = $request->category_id;
$post_id = $model->id;
\App\Post::find($post_id)->categories()->attach($category_id);
}
}
ActionEvent::forResourceCreate($request->user(), $model)->save();
collect($callbacks)->each->__invoke();
return $model;
});
return response()->json([
'id' => $model->getKey(),
'resource' => $model->attributesToArray(),
'redirect' => $resource::redirectAfterCreate($request, $request->newResourceWith($model)),
], 201);
}
}
All runs well on my computer. A fun question with me! Hope best to you, and ask me if you need!

Answer 3

What I ended up doing was saving the data on Post Model in boot().
public static function boot()
{
parent::boot();
static::created(function (Post $post) {
$post->categories()->attach([1]);
});
}