Two-step Subform

[w3star]

Hello
I'm trying to recreate the admin view from the example Demo 5 Countries. Specifically, I'm interested in the two-level subform States/Cities. But somehow it's not working. I can create single-level subforms. But I want to be able to include both States and Cities in the same admin view, just like in Countries. Even if I copy everything 1:1, I can't create an admin view like this.
What's the trick?
Regards, Rachel

[lemuelvdm]

Hello, I hope this guide helps you set up the two-level subform structure like in the Demo 5 component (Countries → States → Cities). Below is a simplified breakdown of how to structure both set and get operations to make everything work seamlessly.

---

✅ Step 1: Define the SET Map

The setMap tells the system how to link and save data from the subforms.

$setMap =  [
	'_core' => [ // Parent subform: States
		'table' => 'state',         // Table storing parent subform data
		'indexKey' => 'guid',       // Unique ID field for states
		'linkKey' => 'country',     // Field linking state to country
		'linkValue' => $data['guid'] ?? '' // Current country GUID
	],
	'cities' => [ // Child subform: Cities
		'table' => 'city',          // Table storing child subform data
		'indexKey' => 'guid',       // Unique ID field for cities
		'linkKey' => 'state',       // Field linking city to state
		'linkValue' => 'state:guid' // Reference to parent's GUID
	]
];

Super___9d76b8dc_3883_4755_b11c_131d19ca8a53___Power::_('Data.MultiSubform')->set([[[field]]] ?? [], $setMap);

---

✅ Step 2: Define the GET Map

The getMap is for retrieving the existing data for editing/viewing.

$getMap =  [
	'_core' => [ // Parent subform: States
		'table' => 'state',
		'linkValue' => $item->guid ?? '',   // Current country GUID
		'linkKey' => 'country',
		'field' => 'state',                 // Name used for storing states
		'get' => ['guid','name','type','latitude','longitude','iso2','fips_code','wikidataid']
	],
	'cities' => [ // Child subform: Cities
		'table' => 'city',
		'linkValue' => 'state:guid',       // Pull cities by their linked state
		'linkKey' => 'state',
		'get' => ['guid','name','latitude','longitude','wikidataid']
	]
];

[[[field]]] = Super___9d76b8dc_3883_4755_b11c_131d19ca8a53___Power::_('Data.MultiSubform')->get($getMap);

---

📘 Concept Breakdown

🔷 1. SET Parent Subform (States)

• table: Where data is saved (state)
• indexKey: Unique ID used (guid)
• linkKey: Foreign key in state table that links to the parent table (country)
• linkValue: The GUID of the current country (usually $data['guid'] ?? '')

🔷 2. SET Child Subform (Cities)

• table: Table to store cities (city)
• indexKey: Unique ID (guid)
• linkKey: Foreign key in the city table that links to state
• linkValue: 'state:guid' means “use the guid field from the parent subform (state)”

🔷 3. GET Parent Subform

• table: Where data is retrieved from (state)
• linkValue: Current country GUID ($item->guid ?? '')
• linkKey: Field in state that links it to country
• field: Identifier used in code to access the data (state)
• get: List of fields to retrieve from the state table

🔷 4. GET Child Subform

• table: Data comes from city
• linkValue: 'state:guid' – links to the current state's GUID
• linkKey: The field in city that connects it to state
• get: Fields to retrieve from the city table

---

⚠️ Important Notes

• Set the admin behavior to NoneDB when using subforms that store data in different tables.
• Make sure all hidden fields and foreign keys exist in your system.
• If you're using a recent version of JCB with Demo 5 installed, reuse those existing fields where possible.
• This setup is powerful and scalable — especially useful when you're dealing with relational data across multiple tables.

---

🧠 Summary

Level	Table	Links To	linkKey	linkValue
Country
↳ State	state	country GUID	country	$data['guid'] or $item->guid
↳↳ City	city	state GUID	state	'state:guid'

Once your linking fields and table references are correct, this structure will handle complex multi-table inputs smoothly!

[w3star]

Hallo Lemuel Thank you very much for your detail explanations. Unfortunately I can not do it yet. Maybe it’s because of the field state (marked yellow below). What do you mean with ‘Identifier used in code to access the data (state)’? Witch object is mentioned here? May I ask you to explain it? Thank you and greetings Rachel Von: Lemuel ***@***.***> Gesendet: Montag, 9. Juni 2025 18:11 An: vdm-io/Joomla-Component-Builder ***@***.***> Cc: STAR ***@***.***>; Author ***@***.***> Betreff: Re: [vdm-io/Joomla-Component-Builder] Two-step Subform (Discussion #989) Hello, I hope this guide helps you set up the two-level subform structure like in the Demo 5 component (Countries → States → Cities). Below is a simplified breakdown of how to structure both set and get operations to make everything work seamlessly.

…

_____ ✅ Step 1: Define the SET Map The setMap tells the system how to link and save data from the subforms. $setMap = [ '_core' => [ // Parent subform: States 'table' => 'state', // Table storing parent subform data 'indexKey' => 'guid', // Unique ID field for states 'linkKey' => 'country', // Field linking state to country 'linkValue' => $data['guid'] ?? '' // Current country GUID ], 'cities' => [ // Child subform: Cities 'table' => 'city', // Table storing child subform data 'indexKey' => 'guid', // Unique ID field for cities 'linkKey' => 'state', // Field linking city to state 'linkValue' => 'state:guid' // Reference to parent's GUID ] ]; Super___9d76b8dc_3883_4755_b11c_131d19ca8a53___Power::_('Data.MultiSubform')->set([[[field]]] ?? [], $setMap); _____ ✅ Step 2: Define the GET Map The getMap is for retrieving the existing data for editing/viewing. $getMap = [ '_core' => [ // Parent subform: States 'table' => 'state', 'linkValue' => $item->guid ?? '', // Current country GUID 'linkKey' => 'country', 'field' => 'state', // Name used for storing states 'get' => ['guid','name','type','latitude','longitude','iso2','fips_code','wikidataid'] ], 'cities' => [ // Child subform: Cities 'table' => 'city', 'linkValue' => 'state:guid', // Pull cities by their linked state 'linkKey' => 'state', 'get' => ['guid','name','latitude','longitude','wikidataid'] ] ]; [[[field]]] = Super___9d76b8dc_3883_4755_b11c_131d19ca8a53___Power::_('Data.MultiSubform')->get($getMap); _____ 📘 Concept Breakdown 🔷 1. SET Parent Subform (States) * table: Where data is saved (state) * indexKey: Unique ID used (guid) * linkKey: Foreign key in state table that links to the parent table (country) * linkValue: The GUID of the current country (usually $data['guid'] ?? '') 🔷 2. SET Child Subform (Cities) * table: Table to store cities (city) * indexKey: Unique ID (guid) * linkKey: Foreign key in the city table that links to state * linkValue: 'state:guid' means “use the guid field from the parent subform (state)” 🔷 3. GET Parent Subform * table: Where data is retrieved from (state) * linkValue: Current country GUID ($item->guid ?? '') * linkKey: Field in state that links it to country * field: Identifier used in code to access the data (state) * get: List of fields to retrieve from the state table 🔷 4. GET Child Subform * table: Data comes from city * linkValue: 'state:guid' – links to the current state's GUID * linkKey: The field in city that connects it to state * get: Fields to retrieve from the city table

_____ ⚠️ Important Notes * Set the admin behavior to NoneDB when using subforms that store data in different tables. * Make sure all hidden fields and foreign keys exist in your system. * If you're using a recent version of JCB with Demo 5 installed, reuse those existing fields where possible. * This setup is powerful and scalable — especially useful when you're dealing with relational data across multiple tables.

_____ 🧠 Summary Level Table Links To linkKey linkValue Country ↳ State state country GUID country $data['guid'] or $item->guid ↳↳ City city state GUID state 'state:guid' Once your linking fields and table references are correct, this structure will handle complex multi-table inputs smoothly! — Reply to this email directly, view it on GitHub <https://github.com/vdm-io/Joomla-Component-Builder/discussions/989#discussioncomment-13411757> , or unsubscribe <https://github.com/notifications/unsubscribe-auth/AXXRM6LNM3A7B4B53HF76XL3CWWXVAVCNFSM6AAAAAB65EPEASVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTGNBRGE3TKNY> . You are receiving this because you authored the thread.Message ID: ***@***.***>