# MIGXdb create custom package with many to many relationship

**URL:** <https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080>\
**Category:** Extras\
**Tags:** migxdb\
**Created:** [October 8, 2024, 3:10pm UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080 "2024-10-08T15:10:05Z")\
**Posts on this page:** 14\
**Page:** 1

<div class="post-metadata">

**Author:** ![vibedesign](https://community.modx.com/user_avatar/community.modx.com/vibedesign/32/741_2.png) [@vibedesign](https://community.modx.com/u/vibedesign)\
**Post date:** [October 8, 2024, 3:10pm UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080/1 "2024-10-08T15:10:05Z")

</div>

I’m (still) struggeling a bit to create a correct schema for my custom package using migxdb. My goal is to show references from a client in certain categories. One reference can have multiple categories assigned and also one category can have multiple references linked, therefore my conclusion was a many to many setup:

> **show schema**
>
> ```xml
> <?xml version="1.0" encoding="UTF-8"?>
> 
> <model package="Referenzen\Model\" baseClass="xPDO\Om\xPDOObject" platform="mysql" defaultEngine="InnoDB" phpdoc-package="" phpdoc-subpackage="" version="3.0">
> 
> <object class="Kategorie" table="referenzen_kategorien" extends="xPDO\Om\xPDOSimpleObject">
> <field key="name" dbtype="varchar" phptype="string" precision="100" null="false" default="" index="index"/>
> <field key="description" dbtype="text" phptype="string" null="false" default="" />
> <field key="image" dbtype="text" phptype="string" null="false" default="" />
> 
> <composite alias="Referenzen" class="Referenzen\Model\KategorieReferenz" local="id" foreign="kategorie_id" cardinality="many" owner="local" />
> 
> <index alias="name" name="name" primary="false" unique="false" type="BTREE">
> <column key="name" length="" collation="A" null="false" />
> </index>
> </object>
> 
> <object class="Referenz" table="referenzen" extends="xPDO\Om\xPDOSimpleObject">
> <field key="title" dbtype="varchar" phptype="string" precision="190" null="false" default="" index="index" />
> <field key="description" dbtype="text" phptype="string" null="false" default="" />
> <field key="images" dbtype="text" phptype="string" null="false" default="" />
> 
> <composite alias="KategorienZuReferenzen" class="Referenzen\Model\KategorieReferenz" local="id" foreign="referenz_id" cardinality="many" owner="local" />
> 
> <index alias="title" name="title" primary="false" unique="false" type="BTREE">
> <column key="title" length="" collation="A" null="false" />
> </index>
> </object>
> 
> <object class="KategorieReferenz" table="referenzen_kategorie_referenz" extends="xPDOSimpleObject">
> <field key="referenz_id" dbtype="int" precision="10" attributes="unsigned" phptype="integer" null="false" default="0" index="index" />
> <field key="kategorie_id" dbtype="int" precision="10" attributes="unsigned" phptype="integer" null="false" default="0" index="index" />
> 
> <aggregate alias="Referenz" class="Referenzen\Model\Referenz" local="referenz_id" foreign="id" cardinality="one" owner="foreign" />
> <aggregate alias="Kategorie" class="Referenzen\Model\Kategorie" local="kategorie_id" foreign="id" cardinality="one" owner="foreign" />
> 
> <index alias="referenz_id" name="referenz_id" primary="false" unique="false" type="BTREE">
> <column key="referenz_id" length="" collation="A" null="false" />
> </index>
> <index alias="kategorie_id" name="kategorie_id" primary="false" unique="false" type="BTREE">
> <column key="kategorie_id" length="" collation="A" null="false" />
> </index>
> </object>
> 
> </model>
> 
> ```

I’ve read through [these docs](https://docs.modx.com/3.x/en/extending-modx/xpdo/custom-models/defining-a-schema/relationships#relating-many-to-many) which helped me creating the above schema, but now I’m stuck when I actually try to link the two parts together in the CMP.

Do I have to create an additional field under references where I can store the IDs of the selected categories? To be clear, I know how to create a dropdown of the values from the category table using a `@CHUNK` input with a `migxLoopCollection` call.

What I don’t yet understand is how this works in the background as I would assume my connecting table from the “KategorieReferenz” class should be populated somehow.

_MODX 3.0.5_  
_MIGX 3.0.2-beta1_

---

<div class="post-metadata">

**Author:** ![halftrainedharry](https://community.modx.com/user_avatar/community.modx.com/halftrainedharry/32/1063_2.png) [@halftrainedharry](https://community.modx.com/u/halftrainedharry)\
**Post date:** [October 8, 2024, 3:40pm UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080/2 "2024-10-08T15:40:59Z")

</div>

A common way to do this is to use the `aftergetfields` and `aftersave` hooks.

You already did this once. See [this thread](https://community.modx.com/t/migxloopcollection-filter-results-by-single-select-dropdown-in-frontend-also-how-to-setup-a-man2many-custom-table/3059/5).

* * *

I also created a Youtube video that explains the process.

[![](https://modx-community.s3.dualstack.us-east-1.amazonaws.com/original/2X/b/bae8af83626d2026f95d0993ba621f2ff1bbe8b8.jpeg "MODX 2.x - MIGXdb - Many-to-many relationship") ](https://www.youtube.com/watch?v=831qgYLAc-E)

It’s for MODX 2.x (but it should still mostly work the same.)

---

<div class="post-metadata">

**Author:** ![vibedesign](https://community.modx.com/user_avatar/community.modx.com/vibedesign/32/741_2.png) [@vibedesign](https://community.modx.com/u/vibedesign)\
**Post date:** [October 8, 2024, 4:18pm UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080/3 "2024-10-08T16:18:33Z")

</div>

> [@halftrainedharry](#):
>
> You already did this once. See [this thread](https://community.modx.com/t/migxloopcollection-filter-results-by-single-select-dropdown-in-frontend-also-how-to-setup-a-man2many-custom-table/3059/5).

Yes, I saw this as well but couldn’t really make sense of it anymore. 😅

* * *

Thank you, I think I understand the process now better, also thanks to your great video!

Do I have to adjust any of the pathnames according to the new MODX3 update?  
I’ve adjusted your snippets now to this setup, but I can’t save any items in the CMP.

Here’s the updated snippets:

```php
// referenzen_aftergetfields

$base_path = $modx->getOption('core_path').'components/referenzen/';
$modx->addPackage('referenzen', $base_path.'model/');

if ($object) {
    $record_fields = $object->get('record_fields');
    $referenz_id = $record_fields['object_id'];
    
    $category_ids = array();
    $result = $modx->getCollection('KategorieReferenz', array('referenz_id' => $referenz_id));
    foreach($result as $res){
        $category_ids[] = $res->get('category_id');
    }
    
    $record_fields['kategorien'] = implode("||",$category_ids);
    $object->set('record_fields',$record_fields);
}

return '';

```

```php
// referenzen_aftersave

$base_path = $modx->getOption('core_path').'components/referenzen/';
$modx->addPackage('referenzen', $base_path.'model/');

$object = & $modx->getOption('object',$scriptProperties,null);
$postvalues = $modx->getOption('postvalues',$scriptProperties,array());

$config = array();
$config['link_classname'] = 'KategorieReferenz';
$config['link_alias'] = 'Kategorien';
$config['postfield'] = 'kategorien';
$config['id_field'] = 'referenz_id';
$config['link_field'] = 'kategorie_id';

$modx->migx->handleRelatedLinks($object, $postvalues, $config);

```

* * *

**Edit:** I can create (open) the CMP entry now, but I can’t save it. If it’s not a new MODX3 pathing issue, I guess I mixed up some fields in the aftersave snippet?

---

<div class="post-metadata">

**Author:** ![halftrainedharry](https://community.modx.com/user_avatar/community.modx.com/halftrainedharry/32/1063_2.png) [@halftrainedharry](https://community.modx.com/u/halftrainedharry)\
**Post date:** [October 8, 2024, 4:33pm UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080/4 "2024-10-08T16:33:16Z")

</div>

> [@vibedesign](#):
>
> ```auto
> $base_path = $modx->getOption('core_path').'components/referenzen/';
> $modx->addPackage('referenzen', $base_path.'model/');
> 
> ```

In MODX 3, the package should already get added in the `bootstrap.php` file in `core\components\<package_name>`. So this isn’t necessary anymore.

> [@vibedesign](#):
>
> `$modx->getCollection('KategorieReferenz',`

In MODX 3, you have to used the full class name (with the namespace) instead of just `KategorieReferenz` → `Referenzen\Model\KategorieReferenz`

---

<div class="post-metadata">

**Author:** ![vibedesign](https://community.modx.com/user_avatar/community.modx.com/vibedesign/32/741_2.png) [@vibedesign](https://community.modx.com/u/vibedesign)\
**Post date:** [October 8, 2024, 5:10pm UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080/5 "2024-10-08T17:10:54Z")

</div>

Thank you, after sorting out some naming issues, I got it to work now!

> **Updated, working solution**
>
> Schema
> 
> ```xml
> <?xml version="1.0" encoding="UTF-8"?>
> 
> <model package="Referenzen\Model\" baseClass="xPDO\Om\xPDOObject" platform="mysql" defaultEngine="InnoDB" phpdoc-package="" phpdoc-subpackage="" version="3.0">
> 
> <object class="Kategorie" table="referenzen_kategorien" extends="xPDO\Om\xPDOSimpleObject">
> <field key="name" dbtype="varchar" phptype="string" precision="100" null="false" default="" index="index"/>
> <field key="description" dbtype="text" phptype="string" null="false" default="" />
> <field key="image" dbtype="text" phptype="string" null="false" default="" />
> 
> <field key="pos" dbtype="int" precision="10" phptype="integer" null="false" default="0" index="index" />
> <field key="published" dbtype="tinyint" precision="1" attributes="unsigned" phptype="integer" null="false" default="0" />
> 
> <composite alias="KategorienZuReferenzen" class="Referenzen\Model\KategorieReferenz" local="id" foreign="kategorie_id" cardinality="many" owner="local" />
> 
> <index alias="name" name="name" primary="false" unique="false" type="BTREE">
> <column key="name" length="" collation="A" null="false" />
> </index>
> <index alias="pos" name="pos" primary="false" unique="false" type="BTREE">
> <column key="pos" length="" collation="A" null="false" />
> </index>
> </object>
> 
> <object class="Referenz" table="referenzen" extends="xPDO\Om\xPDOSimpleObject">
> <field key="title" dbtype="varchar" phptype="string" precision="190" null="false" default="" index="index" />
> <field key="description" dbtype="text" phptype="string" null="false" default="" />
> <field key="images" dbtype="text" phptype="string" null="false" default="" />
> 
> <field key="pos" dbtype="int" precision="10" phptype="integer" null="false" default="0" index="index" />
> <field key="published" dbtype="tinyint" precision="1" attributes="unsigned" phptype="integer" null="false" default="0" />
> 
> <composite alias="KategorienZuReferenzen" class="Referenzen\Model\KategorieReferenz" local="id" foreign="referenz_id" cardinality="many" owner="local" />
> 
> <index alias="title" name="title" primary="false" unique="false" type="BTREE">
> <column key="title" length="" collation="A" null="false" />
> </index>
> <index alias="pos" name="pos" primary="false" unique="false" type="BTREE">
> <column key="pos" length="" collation="A" null="false" />
> </index>
> </object>
> 
> <object class="KategorieReferenz" table="referenzen_kategorie_referenz" extends="xPDOSimpleObject">
> <field key="referenz_id" dbtype="int" precision="10" attributes="unsigned" phptype="integer" null="false" default="0" index="index" />
> <field key="kategorie_id" dbtype="int" precision="10" attributes="unsigned" phptype="integer" null="false" default="0" index="index" />
> 
> <aggregate alias="Referenz" class="Referenzen\Model\Referenz" local="referenz_id" foreign="id" cardinality="one" owner="foreign" />
> <aggregate alias="Kategorie" class="Referenzen\Model\Kategorie" local="kategorie_id" foreign="id" cardinality="one" owner="foreign" />
> 
> <index alias="referenz_id" name="referenz_id" primary="false" unique="false" type="BTREE">
> <column key="referenz_id" length="" collation="A" null="false" />
> </index>
> <index alias="kategorie_id" name="kategorie_id" primary="false" unique="false" type="BTREE">
> <column key="kategorie_id" length="" collation="A" null="false" />
> </index>
> </object>
> 
> </model>
> 
> ```
> 
> Snippets
> 
> ```php
> // referenzen_aftergetfields
> 
> if ($object) {
> $record_fields = $object->get('record_fields');
> $referenz_id = $record_fields['object_id'];
>   
> $kategorie_ids = array();
> $result = $modx->getCollection('Referenzen\Model\KategorieReferenz', array('referenz_id' => $referenz_id));
> foreach($result as $res){
> $kategorie_ids[] = $res->get('kategorie_id');
> }
>   
> $record_fields['kategorien'] = implode("||",$kategorie_ids);
> $object->set('record_fields',$record_fields);
> }
> 
> return '';
> 
> ```
> 
> ```php
> // referenzen_aftersave
> 
> $object = & $modx->getOption('object',$scriptProperties,null);
> $postvalues = $modx->getOption('postvalues',$scriptProperties,array());
> 
> $config = array();
> $config['link_classname'] = 'Referenzen\Model\KategorieReferenz';
> $config['link_alias'] = 'KategorienZuReferenzen';
> $config['postfield'] = 'kategorien';
> $config['id_field'] = 'referenz_id';
> $config['link_field'] = 'kategorie_id';
> 
> $modx->migx->handleRelatedLinks($object, $postvalues, $config);
> 
> ```

* * *

One additional question:

Is there an easy way to show the selected category names in the columns section of the CMP?

---

<div class="post-metadata">

**Author:** ![halftrainedharry](https://community.modx.com/user_avatar/community.modx.com/halftrainedharry/32/1063_2.png) [@halftrainedharry](https://community.modx.com/u/halftrainedharry)\
**Post date:** [October 8, 2024, 6:08pm UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080/6 "2024-10-08T18:08:59Z")

</div>

> [@vibedesign](#):
>
> Is there an easy way to show the selected category names in the columns section of the CMP?

You can use a `this.renderChunk` renderer for the column.

There is an example in the Youtube video I linked above (around the 10 minutes mark).

---

<div class="post-metadata">

**Author:** ![vibedesign](https://community.modx.com/user_avatar/community.modx.com/vibedesign/32/741_2.png) [@vibedesign](https://community.modx.com/u/vibedesign)\
**Post date:** [October 9, 2024, 10:58am UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080/7 "2024-10-09T10:58:28Z")

</div>

I quickly want to chime in here again as I noticed an issue while using the `renderChunk` together with another column which has the `this.renderClickCrossTick` renderer for the published field.

When I click the crosstick to publish or unpublish, my set categories get deleted. I assume this has something to do with the snippets that might not get fired doing this? Is there an easy fix for this? If not I could go back to just using the `this.renderCrossTick` renderer I guess.

---

<div class="post-metadata">

**Author:** ![halftrainedharry](https://community.modx.com/user_avatar/community.modx.com/halftrainedharry/32/1063_2.png) [@halftrainedharry](https://community.modx.com/u/halftrainedharry)\
**Post date:** [October 9, 2024, 3:10pm UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080/8 "2024-10-09T15:10:46Z")

</div>

> [@vibedesign](#):
>
> When I click the crosstick to publish or unpublish, my set categories get deleted.

Is this in a MIGXdb CMP or in a MIGX TV?

* * *

In a CMP, when you click the field with the `this.renderClickCrossTick` renderer, an AJAX request (with `action = "mgr/migxdb/update"`) runs and then all the data in the grid is reloaded (AJAX request with `action = "mgr/migxdb/getlist"`) the same way as when you click the reload button (↻) under the grid.  
All the `renderChunk` chunks should then be parsed again in this _getlist_ processor.

---

<div class="post-metadata">

**Author:** ![vibedesign](https://community.modx.com/user_avatar/community.modx.com/vibedesign/32/741_2.png) [@vibedesign](https://community.modx.com/u/vibedesign)\
**Post date:** [October 9, 2024, 3:29pm UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080/9 "2024-10-09T15:29:13Z")

</div>

This is in a migxdb CMP, not a TV.

---

<div class="post-metadata">

**Author:** ![halftrainedharry](https://community.modx.com/user_avatar/community.modx.com/halftrainedharry/32/1063_2.png) [@halftrainedharry](https://community.modx.com/u/halftrainedharry)\
**Post date:** [October 9, 2024, 4:38pm UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080/10 "2024-10-09T16:38:58Z")

</div>

Not sure what the problem is then.

If you can provide your MIGX configuration, I can take a look at it.

---

<div class="post-metadata">

**Author:** ![vibedesign](https://community.modx.com/user_avatar/community.modx.com/vibedesign/32/741_2.png) [@vibedesign](https://community.modx.com/u/vibedesign)\
**Post date:** [October 9, 2024, 4:50pm UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080/11 "2024-10-09T16:50:25Z")

</div>

Sure!

> **Config**
>
> ```json
> {
> "formtabs":[
> {
> "MIGX_id":2,
> "caption":"Referenz",
> "print_before_tabs":"0",
> "fields":[
> {
> "MIGX_id":6,
> "field":"id",
> "caption":"ID",
> "description":"",
> "description_is_code":"0",
> "inputTV":"",
> "inputTVtype":"",
> "validation":"",
> "configs":"",
> "restrictive_condition":"",
> "display":"none",
> "sourceFrom":"config",
> "sources":"",
> "inputOptionValues":"",
> "default":"",
> "useDefaultIfEmpty":"0",
> "pos":1
> },
> {
> "MIGX_id":7,
> "field":"title",
> "caption":"Titel",
> "description":"",
> "description_is_code":"0",
> "inputTV":"",
> "inputTVtype":"",
> "validation":"",
> "configs":"",
> "restrictive_condition":"",
> "display":"",
> "sourceFrom":"config",
> "sources":"",
> "inputOptionValues":"",
> "default":"",
> "useDefaultIfEmpty":"0",
> "pos":2
> },
> {
> "MIGX_id":13,
> "field":"longtitle",
> "caption":"Langer Titel",
> "description":"",
> "description_is_code":"0",
> "inputTV":"",
> "inputTVtype":"",
> "validation":"",
> "configs":"",
> "restrictive_condition":"",
> "display":"",
> "sourceFrom":"config",
> "sources":"",
> "inputOptionValues":"",
> "default":"",
> "useDefaultIfEmpty":"0",
> "pos":3
> },
> {
> "MIGX_id":8,
> "field":"description",
> "caption":"Beschreibung",
> "description":"",
> "description_is_code":"0",
> "inputTV":"",
> "inputTVtype":"textarea",
> "validation":"",
> "configs":"",
> "restrictive_condition":"",
> "display":"",
> "sourceFrom":"config",
> "sources":"",
> "inputOptionValues":"",
> "default":"",
> "useDefaultIfEmpty":"0",
> "pos":4
> },
> {
> "MIGX_id":12,
> "field":"kategorien",
> "caption":"Kategorie",
> "description":"",
> "description_is_code":"0",
> "inputTV":"",
> "inputTVtype":"listbox-multiple",
> "validation":"",
> "configs":{
> "typeAhead":true,
> "typeAheadDelay":250
> },
> "restrictive_condition":"",
> "display":"",
> "sourceFrom":"config",
> "sources":"",
> "inputOptionValues":"@SELECT `name`, `id` FROM `mx_client_kategorien`",
> "default":"",
> "useDefaultIfEmpty":"0",
> "pos":5
> },
> {
> "MIGX_id":9,
> "field":"image",
> "caption":"Bild",
> "description":"",
> "description_is_code":"0",
> "inputTV":"",
> "inputTVtype":"imageplus",
> "validation":"",
> "configs":"",
> "restrictive_condition":"",
> "display":"",
> "sourceFrom":"config",
> "sources":"",
> "inputOptionValues":"",
> "default":"",
> "useDefaultIfEmpty":"0",
> "pos":6
> },
> {
> "MIGX_id":10,
> "field":"pos",
> "caption":"Position",
> "description":"",
> "description_is_code":"0",
> "inputTV":"",
> "inputTVtype":"",
> "validation":"",
> "configs":"",
> "restrictive_condition":"",
> "display":"none",
> "sourceFrom":"config",
> "sources":"",
> "inputOptionValues":"",
> "default":"",
> "useDefaultIfEmpty":"0",
> "pos":7
> },
> {
> "MIGX_id":11,
> "field":"published",
> "caption":"Aktiv",
> "description":"",
> "description_is_code":"0",
> "inputTV":"",
> "inputTVtype":"checkbox",
> "validation":"",
> "configs":"",
> "restrictive_condition":"",
> "display":"",
> "sourceFrom":"config",
> "sources":"",
> "inputOptionValues":"Ja==1",
> "default":"0",
> "useDefaultIfEmpty":"0",
> "pos":8
> }
> ],
> "pos":1
> }
> ],
> "contextmenus":"update||duplicate||publish||unpublish||remove",
> "actionbuttons":"addItem",
> "columnbuttons":"publish||unpublish||remove",
> "filters":"",
> "extended":{
> "migx_add":"Referenz hinzuf\u00fcgen",
> "disable_add_item":"",
> "add_items_directly":"",
> "formcaption":"Neue Referenz",
> "update_win_title":"Referenzen",
> "win_id":"referenzen",
> "maxRecords":"",
> "addNewItemAt":"bottom",
> "media_source_id":"",
> "multiple_formtabs":"",
> "multiple_formtabs_label":"",
> "multiple_formtabs_field":"",
> "multiple_formtabs_optionstext":"",
> "multiple_formtabs_optionsvalue":"",
> "actionbuttonsperrow":4,
> "winbuttonslist":"",
> "extrahandlers":"",
> "filtersperrow":4,
> "packageName":"Client\\Model\\","classname":"Client\\Model\\clientReferenz","task":"","getlistsort":"pos","getlistsortdir":"ASC","sortconfig":"","gridpagesize":25,"use_custom_prefix":"0","prefix":"","grid":"dragdrop","gridload_mode":1,"check_resid":1,"check_resid_TV":"","join_alias":"","has_jointable":"yes","getlistwhere":"","joins":"","hooksnippets":{"aftergetfields":"referenzen_aftergetfields","aftersave":"referenzen_aftersave"},"cmpmaincaption":"Architekturb\u00fcro Ro\u00dfbach","cmptabcaption":"Referenzen","cmptabdescription":"Referenzen","cmptabcontroller":"","winbuttons":"","onsubmitsuccess":"","submitparams":""},"permissions":{"apiaccess":"","view":"","list":"","save":"","create":"","remove":"","delete":"","publish":"","unpublish":"","viewdeleted":"","viewunpublished":""},"fieldpermissions":"","columns":[{"MIGX_id":8,"header":"ID","dataIndex":"id","width":10,"sortable":true,"show_in_grid":1,"customrenderer":"","renderer":"","clickaction":"","selectorconfig":"","renderchunktpl":"","renderoptions":"","editor":""},{"MIGX_id":9,"header":"Position","dataIndex":"pos","width":"","sortable":true,"show_in_grid":"0","customrenderer":"","renderer":"","clickaction":"","selectorconfig":"","renderchunktpl":"","renderoptions":"","editor":""},{"MIGX_id":2,"header":"Titel","dataIndex":"title","width":"","sortable":true,"show_in_grid":1,"customrenderer":"","renderer":"","clickaction":"","selectorconfig":"","renderchunktpl":"","renderoptions":"","editor":""},{"MIGX_id":11,"header":"Langer Titel","dataIndex":"longtitle","width":"","sortable":true,"show_in_grid":1,"customrenderer":"","renderer":"","clickaction":"","selectorconfig":"","renderchunktpl":"","renderoptions":"","editor":""},{"MIGX_id":6,"header":"Kategorie","dataIndex":"kategorien","width":"","sortable":"false","show_in_grid":1,"customrenderer":"","renderer":"this.renderChunk","clickaction":"","selectorconfig":"","renderchunktpl":"[
> [
> migxLoopCollection?\n &packageName=`Client\\Model\\`\n &classname=`Client\\Model\\clientKategorie`\n &joins=`[
> {
> \"alias\": \"ReferenzKategorien\"
> }
> ]`\n &where=`{
> \"`ReferenzKategorien`.`referenz_id`\": [
> [
> +id
> ]
> ]
> }`\n &tpl=`@CODE: {
> {
> +name
> }
> }`\n &outputSeparator=`,
> `\n
> ]
> ]","renderoptions":"","editor":""},{"MIGX_id":5,"header":"Aktiv","dataIndex":"published","width":20,"sortable":true,"show_in_grid":1,"customrenderer":"","renderer":"this.renderCrossTick","clickaction":"","selectorconfig":"","renderchunktpl":"","renderoptions":"","editor":""}],"category":""}
> 
> ```

> **Schema**
>
> ```xml
> <?xml version="1.0" encoding="UTF-8"?>
> 
> <model package="Client\Model\" baseClass="xPDO\Om\xPDOObject" platform="mysql" defaultEngine="InnoDB" phpdoc-package="" phpdoc-subpackage="" version="3.0">
> 
> <!-- REFERENZ -->
> <object class="clientReferenz" table="client_referenzen" extends="xPDO\Om\xPDOSimpleObject">
> <field key="title" dbtype="varchar" phptype="string" precision="190" null="false" default="" index="index" />
> <field key="longtitle" dbtype="varchar" phptype="string" precision="190" null="false" default="" />
> <field key="description" dbtype="text" phptype="string" null="false" default="" />
> <field key="image" dbtype="text" phptype="string" null="false" default="" />
> <field key="pos" dbtype="int" precision="10" phptype="integer" null="false" default="0" index="index" />
> <field key="published" dbtype="tinyint" precision="1" attributes="unsigned" phptype="integer" null="false" default="0" />
> 
> <composite alias="ReferenzKategorien" class="Client\Model\clientReferenzKategorie" local="id" foreign="referenz_id" cardinality="many" owner="local" />
> 
> <index alias="title" name="title" primary="false" unique="false" type="BTREE">
> <column key="title" length="" collation="A" null="false" />
> </index>
> <index alias="pos" name="pos" primary="false" unique="false" type="BTREE">
> <column key="pos" length="" collation="A" null="false" />
> </index>
> </object>
> 
> <!-- KATEGORIE -->
> <object class="clientKategorie" table="client_kategorien" extends="xPDO\Om\xPDOSimpleObject">
> <field key="name" dbtype="varchar" phptype="string" precision="100" null="false" default="" index="index"/>
> <field key="description" dbtype="text" phptype="string" null="false" default="" />
> <field key="image" dbtype="text" phptype="string" null="false" default="" />
> <field key="pos" dbtype="int" precision="10" phptype="integer" null="false" default="0" index="index" />
> <field key="published" dbtype="tinyint" precision="1" attributes="unsigned" phptype="integer" null="false" default="0" />
> 
> <composite alias="ReferenzKategorien" class="Client\Model\clientReferenzKategorie" local="id" foreign="kategorie_id" cardinality="many" owner="local" />
> 
> <index alias="name" name="name" primary="false" unique="false" type="BTREE">
> <column key="name" length="" collation="A" null="false" />
> </index>
> <index alias="pos" name="pos" primary="false" unique="false" type="BTREE">
> <column key="pos" length="" collation="A" null="false" />
> </index>
> </object>
> 
> <!-- KATEGORIE-REFERENZ -->
> <object class="clientReferenzKategorie" table="client_referenzkategorie" extends="xPDOSimpleObject">
> <field key="referenz_id" dbtype="int" precision="10" attributes="unsigned" phptype="integer" null="false" default="0" />
> <field key="kategorie_id" dbtype="int" precision="10" attributes="unsigned" phptype="integer" null="false" default="0" />
> 
> <aggregate alias="Referenz" class="Client\Model\clientReferenz" local="referenz_id" foreign="id" cardinality="one" owner="foreign" />
> <aggregate alias="Kategorie" class="Client\Model\clientKategorie" local="kategorie_id" foreign="id" cardinality="one" owner="foreign" />
> 
> <index alias="referenz_id" name="referenz_id" primary="false" unique="false" type="BTREE">
> <column key="referenz_id" length="" collation="A" null="false" />
> </index>
> <index alias="kategorie_id" name="kategorie_id" primary="false" unique="false" type="BTREE">
> <column key="kategorie_id" length="" collation="A" null="false" />
> </index>
> </object>
> 
> </model>
> 
> ```

---

<div class="post-metadata">

**Author:** ![halftrainedharry](https://community.modx.com/user_avatar/community.modx.com/halftrainedharry/32/1063_2.png) [@halftrainedharry](https://community.modx.com/u/halftrainedharry)\
**Post date:** [October 9, 2024, 7:43pm UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080/12 "2024-10-09T19:43:43Z")

</div>

Ok, I found the issue.

The problem is that the `aftersave` hook snippet is also executed when the item is published/unpublished. But because there is no data for the field “kategorien” available on these events, the current code assumes that “kategorien” is just empty and deletes all existing database entries.

To fix it, you have to adjust the `aftersave` hook snippet.  
Here is a possible solution, that checks if “kategorien” exists, before calling `$modx->migx->handleRelatedLinks()`.

```auto
<?php
// referenzen_aftersave

$object = & $modx->getOption('object',$scriptProperties,null);
$postvalues = $modx->getOption('postvalues',$scriptProperties,array());

$config = array();
$config['link_classname'] = 'Client\Model\clientReferenzKategorie';
$config['link_alias'] = 'ReferenzKategorien';
$config['postfield'] = 'kategorien';
$config['id_field'] = 'referenz_id';
$config['link_field'] = 'kategorie_id';

// NEW CODE | Check if there is any data for the field "kategorien" available
if (!isset($postvalues[$config['postfield']])){
    return;
}

$modx->migx->handleRelatedLinks($object, $postvalues, $config);

```

* * *

Other minor issues:

- Under “MIGXdb-Settings” you only need to fill in the field “Package” if you have custom processors or renderers in files. In that case use `client` instead of `Client\Model\` as the value. Otherwise you can leave the field empty.
- When calling `migxLoopCollection` in the renderChunk renderer, you don’t need the property `&packageName`.

---

<div class="post-metadata">

**Author:** ![vibedesign](https://community.modx.com/user_avatar/community.modx.com/vibedesign/32/741_2.png) [@vibedesign](https://community.modx.com/u/vibedesign)\
**Post date:** [October 9, 2024, 8:35pm UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080/13 "2024-10-09T20:35:14Z")

</div>

Thank you very much for the research and the additional notes on my config! Works great now!

---

<div class="post-metadata">

**Author:** ![system](https://community.modx.com/user_avatar/community.modx.com/system/32/2_2.png) [@system](https://community.modx.com/u/system)\
**Post date:** [October 11, 2024, 8:35pm UTC](https://community.modx.com/t/migxdb-create-custom-package-with-many-to-many-relationship/8080/14 "2024-10-11T20:35:55Z")

</div>

Closed on October 11, 2024, 8:35pm UTC

This topic was automatically closed 2 days after discussion ended and a solution was marked. New replies are no longer allowed. You can open a new topic by clicking the link icon below the original post or solution and selecting “+ New Topic”.