Soft deleting / detaching and restoring / attaching relationships with composite keys - php

Question

I have 2 models that are joined by a relationship which has a composite key - these are Product and Category. I need to use soft deletes on all tables, so that the models and relationships can be restored if required.
In my Product model I have:
function categories()
{
return $this->belongsToMany('App\Category', 'product_categories')->whereNull('product_categories.deleted_at')->withTimestamps();
}
In my Category model I have:
function products()
{
return $this->belongsToMany('App\Product', 'product_categories')->whereNull('product_categories.deleted_at')->withTimestamps();
}
I read elsewhere about chaining the whereNull method, as queries like $category->products->contains($product->id) were otherwise returning the soft deleted relationships.
My question is what is the best way to handle deleting and restoring these soft deleted relationships? For restoring, for example, I tried:
$product->categories()->restore($category_id);
The above produced an SQL error saying the deleted_at field was ambiguous (because it joined the categories table to product_categories).
Update - It appears the root issue is that the BelongsToMany class does not support soft deletes - so attach, detach and sync all perform hard deletes. What would be the best approach to overriding this class?

Answer 1

Basically, there will be only one deleted_at field and instead of using the $product->categories() use two custom (common) methods in both (Product and Category) models for example, you may create a trait like this:
// SoftDeletePC.php
trait SoftDeletePC {
// SoftDelete
public function softDeleteProductCategory($productId, $categoryId)
{
\DB::table('product_categories')
->where('product_id', $productId)
->where('category_id', $categoryId)
->update(['deleted_at' => \DB::raw('NOW()')]);
}
// Restore
public function restoreProductCategory($productId, $categoryId)
{
\DB::table('product_categories')
->where('product_id', $productId)
->where('category_id', $categoryId)
->update(['deleted_at' => null]);
}
}
Then use this trait in both models using use TraitProductCategory and call the method from both models for example:
// App/Product.php
class product extends Model {
use SoftDeletePC;
}
// App/Category.php
class Category extends Model {
use SoftDeletePC;
}
So, instead of using this:
Product->find(1)->categories()->restore(2);
You may use something like this:
$product = Product->find(1);
$product->softDeleteProductCategory(1, 2); // Set timestamp to deleted_at
$product->restoreProductCategory(1, 2); // Set null to deleted_at
Hope this may work for you.

Answer 2

I have ended up creating some custom methods in my Product model to accomplish what I require - not my ideal solution, but it works nevertheless. My custom sync looks like this:
class Product extends Model
{
// update relationship to categories
function categories_sync($category_ids)
{
// categories
$existing_category_ids = $this->categories()->lists('category_id')->all();
$trashed_category_ids = $this->categories('onlyTrashed')->lists('category_id')->all();
if(is_array($category_ids)) {
foreach($category_ids as $category_id) {
if(in_array($category_id, $trashed_category_ids)) {
$this->categories()->updateExistingPivot($category_id, ['deleted_at' => null]);
}
elseif(!in_array($category_id, $existing_category_ids)) {
$this->categories()->attach($category_id);
}
}
foreach($existing_category_ids as $category_id) {
if(!in_array($category_id, $category_ids)) {
$this->categories()->updateExistingPivot($category_id, ['deleted_at' => date('YmdHis')]);
}
}
}
else {
foreach($existing_category_ids as $category_id) {
$this->categories()->updateExistingPivot($category_id, ['deleted_at' => date('YmdHis')]);
}
}
}
}
The above relies upon an extended categories() method:
// relationship to categories
function categories($trashed=false)
{
if($trashed=='withTrashed') {
return $this->belongsToMany('App\Category', 'product_categories')->withTimestamps();
}
elseif($trashed=='onlyTrashed') {
return $this->belongsToMany('App\Category', 'product_categories')->whereNotNull('product_categories.deleted_at')->withTimestamps();
}
else {
return $this->belongsToMany('App\Category', 'product_categories')->whereNull('product_categories.deleted_at')->withTimestamps();
}
}