# Controling bindings evaluation order

**URL:** <https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842>\
**Category:** Ignition\
**Tags:** ignition81, perspective\
**Created:** [July 3, 2023, 1:09pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842 "2023-07-03T13:09:02Z")\
**Posts on this page:** 20\
**Page:** 1

<div class="post-metadata">

**Author:** ![pascal.fragnoud](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pascal.fragnoud/32/24728_2.png) [@pascal.fragnoud](https://forum.inductiveautomation.com/u/pascal.fragnoud)\
**Post date:** [July 3, 2023, 1:09pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/1 "2023-07-03T13:09:02Z")

</div>

Hello folks,

I've been struggling to find a good way to do something.  
Here's some context:  
I have 3 dropdowns, let's call them dropA, dropB and dropC.  
dropC depends on dropB, and dropB depends on dropA.  
I want to reset the `value` prop of drop B and drop C when the dropdown they depend on change.  
There are many ways to do this: property change scripts, script transforms...

BUT, I also need to pre-load selections when the view is opened, based on parameters.  
I couldn't find a way to reliably set the `prop` values of the 3 dropdowns.  
If they're not set in order (dropA -\> dropB -\> dropC), the values gets reset because of the reset requirement described above.

I can think of convoluted ways to achieve this, but I'd like to pick your brains before I make a mess.  
How would YOU do it ?

---

<div class="post-metadata">

**Author:** ![Transistor](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/transistor/32/3380_2.png) [@Transistor](https://forum.inductiveautomation.com/u/Transistor)\
**Post date:** [July 3, 2023, 1:16pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/2 "2023-07-03T13:16:33Z")

</div>

Can you script an onStart to set `dropA.options` to `null` followed by a line to set the correct options? Maybe you'd need to initialise dropA, B and C to null initially.

---

<div class="post-metadata">

**Author:** ![pascal.fragnoud](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pascal.fragnoud/32/24728_2.png) [@pascal.fragnoud](https://forum.inductiveautomation.com/u/pascal.fragnoud)\
**Post date:** [July 3, 2023, 1:23pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/3 "2023-07-03T13:23:15Z")

</div>

They're null initially, it's their default.

I think I tried an `onStartup` event, uncessfully.  
I may have to try again, as I was so tangled up in my own mess that I might have boinked up a few things.

edit: I was actually hoping for a way of reseting the values that would allow me to just bind them to the parameters. But I guess such a way, if it exists, would be even messier...

---

<div class="post-metadata">

**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [July 3, 2023, 1:39pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/4 "2023-07-03T13:39:34Z")

</div>

> [@pascal.fragnoud](#):
>
> BUT, I also need to pre-load selections when the view is opened, based on parameters.

Describe these dependencies a bit more please.

{I would try to do this with bindings, each with the relevant dependencies. My new SimAids `asList()` function is handy for staging a group of dependencies for a transform, even if one or more is unused.}

---

<div class="post-metadata">

**Author:** ![pascal.fragnoud](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pascal.fragnoud/32/24728_2.png) [@pascal.fragnoud](https://forum.inductiveautomation.com/u/pascal.fragnoud)\
**Post date:** [July 3, 2023, 1:50pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/5 "2023-07-03T13:50:05Z")

</div>

I have 3 database tables, let's call them 'families', 'categories' and 'items'.  
categories have a foreign key to families' id, and items have a FK to categories' id.  
dropA allows the selection of a family, its `options` prop is bound to a parameterless query that fetches all families.  
dropB allows the selection of a category, `options` named query uses dropA's value as its `family_id` parameter  
dropC allows the selection of an item, `options` named query uses dropB's value as its 'category\_id' parameter.

I have a boolean custom prop that's `false` if no item is selected, and `true` otherwise. There's a bunch of things that are only displayed if this prop is `true`.  
I want to clear those things when families or categories change, which is why I want to reset dropC's value.

---

<div class="post-metadata">

**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [July 3, 2023, 1:53pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/6 "2023-07-03T13:53:28Z")

</div>

Sounds like you need to reset DropC's value in property change events on DropA's and dropB's `options` property. Hmm. Values, too.

---

<div class="post-metadata">

**Author:** ![pascal.fragnoud](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pascal.fragnoud/32/24728_2.png) [@pascal.fragnoud](https://forum.inductiveautomation.com/u/pascal.fragnoud)\
**Post date:** [July 3, 2023, 1:55pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/7 "2023-07-03T13:55:39Z")

</div>

The problem with that is when I pre-load values from the view's parameter.

If dropA or dropB's values are set after dropC, its value is reset.  
I tried doing this in a script (startup script and property change script on a parameter), thinking it would set things in order. It didn't.

---

<div class="post-metadata">

**Author:** ![j.israelsen](https://avatars.discourse-cdn.com/v4/letter/j/ad7895/32.png) [@j.israelsen](https://forum.inductiveautomation.com/u/j.israelsen)\
**Post date:** [July 3, 2023, 1:59pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/8 "2023-07-03T13:59:02Z")

</div>

Perhaps it would be useful to re-evaluate how you are attacking the problem?

From a high level conceptual plan of attack, I have generally found when I have a bunch of items that need to interact (or evaluate in a certain order) a single function can alleviate problems.

So basically:

1. Feed data to the function/script (from all of the sources)
2. Have the function determine your order of operation and or interactions
3. Get results from the function (and distribute to all necessary items)

---

<div class="post-metadata">

**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [July 3, 2023, 1:59pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/9 "2023-07-03T13:59:45Z")

</div>

Your parameters supply starting values for DropA, DropB, and DropC? But are stymied by the options arriving slightly later?

---

<div class="post-metadata">

**Author:** ![pascal.fragnoud](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pascal.fragnoud/32/24728_2.png) [@pascal.fragnoud](https://forum.inductiveautomation.com/u/pascal.fragnoud)\
**Post date:** [July 3, 2023, 2:02pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/10 "2023-07-03T14:02:58Z")

</div>

Yep, exactly.

@j.israelsen: I tried. Uncessfully. If you can find a different angle to tackle the problem, I'm all ears. Or, well, eyes.

---

<div class="post-metadata">

**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [July 3, 2023, 2:04pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/11 "2023-07-03T14:04:37Z")

</div>

Hmm. Do you have some sample data I can play with?

---

<div class="post-metadata">

**Author:** ![pascal.fragnoud](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pascal.fragnoud/32/24728_2.png) [@pascal.fragnoud](https://forum.inductiveautomation.com/u/pascal.fragnoud)\
**Post date:** [July 3, 2023, 2:09pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/12 "2023-07-03T14:09:26Z")

</div>

I can put together a minimum working view if that's what you're asking.  
I'll replace the db tables and query bindings with custom props I guess.

---

<div class="post-metadata">

**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [July 3, 2023, 2:11pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/13 "2023-07-03T14:11:26Z")

</div>

> [@pascal.fragnoud](#):
>
> I'll replace the db tables and query bindings with custom props I guess.

Sure, but I'll load them in my DB playground. Named query timing (async behavior, more than absolute time) is certainly significant for this case.

---

<div class="post-metadata">

**Author:** ![j.israelsen](https://avatars.discourse-cdn.com/v4/letter/j/ad7895/32.png) [@j.israelsen](https://forum.inductiveautomation.com/u/j.israelsen)\
**Post date:** [July 3, 2023, 2:18pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/14 "2023-07-03T14:18:52Z")

</div>

> BUT, I also need to pre-load selections when the view is opened, based on parameters.  
> I couldn't find a way to reliably set the `prop` values of the 3 dropdowns.  
> If they're not set in order (dropA -\> dropB -\> dropC), the values gets reset because of the reset requirement described above.

From your initial description, it sounds like your method works except for pre-loading (because of the value change script or something like that)? That sounds like an edge-case. If that's the only issue, could you raise a flag on initialization such that you somehow **disable** your change script during initialization?

---

<div class="post-metadata">

**Author:** ![pascal.fragnoud](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pascal.fragnoud/32/24728_2.png) [@pascal.fragnoud](https://forum.inductiveautomation.com/u/pascal.fragnoud)\
**Post date:** [July 3, 2023, 2:22pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/15 "2023-07-03T14:22:14Z")

</div>

I tried the semaphore way, but what will turn it off ?  
If I can't control initialization order, then the flag might get turned off before initialization is finished.

So, I'd need multiple flags, and it's one of the messes I'm talking about in the first post that I'm trying to avoid.

---

<div class="post-metadata">

**Author:** ![victordcq](https://avatars.discourse-cdn.com/v4/letter/v/f6c823/32.png) [@victordcq](https://forum.inductiveautomation.com/u/victordcq)\
**Post date:** [July 3, 2023, 2:34pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/16 "2023-07-03T14:34:34Z")

</div>

will all 3 preinitial view params always be filled in (if any of them is)?

---

<div class="post-metadata">

**Author:** ![pascal.fragnoud](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pascal.fragnoud/32/24728_2.png) [@pascal.fragnoud](https://forum.inductiveautomation.com/u/pascal.fragnoud)\
**Post date:** [July 3, 2023, 2:35pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/17 "2023-07-03T14:35:21Z")

</div>

They're either all provided, or none of them is.

---

<div class="post-metadata">

**Author:** ![pascal.fragnoud](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pascal.fragnoud/32/24728_2.png) [@pascal.fragnoud](https://forum.inductiveautomation.com/u/pascal.fragnoud)\
**Post date:** [July 3, 2023, 2:53pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/18 "2023-07-03T14:53:22Z")

</div>

Here's a minimal working page.  
Well, working is not exactly the proper word.  
But the 'things' are there.

> ****
>
> ```json
> {
> "custom": {},
> "params": {
> "category_id": "",
> "family_id": "",
> "item_id": ""
> },
> "propConfig": {
> "params.category_id": {
> "paramDirection": "input",
> "persistent": true
> },
> "params.family_id": {
> "paramDirection": "input",
> "persistent": true
> },
> "params.item_id": {
> "onChange": {
> "enabled": null,
> "script": "\tself.getChild(\"root\").getChild(\"families\").getChild(\"Dropdown\").props.value \u003d self.params.family_id\n\tself.getChild(\"root\").getChild(\"categories\").getChild(\"Dropdown\").props.value \u003d self.params.category_id\n\tself.getChild(\"root\").getChild(\"items\").getChild(\"Dropdown\").props.value \u003d self.params.item_id"
> },
> "paramDirection": "input",
> "persistent": true
> }
> },
> "props": {},
> "root": {
> "children": [
> {
> "children": [
> {
> "meta": {
> "name": "Label"
> },
> "position": {
> "basis": "150px"
> },
> "props": {
> "text": "families"
> },
> "type": "ia.display.label"
> },
> {
> "meta": {
> "name": "Dropdown"
> },
> "position": {
> "basis": "256px"
> },
> "propConfig": {
> "props.options": {
> "binding": {
> "config": {
> "queryPath": "sandbox/list_families"
> },
> "type": "query"
> }
> },
> "props.value": {
> "onChange": {
> "enabled": null,
> "script": "\tself.parent.parent.getChild(\"categories\").getChild(\"Dropdown\").props.value \u003d None"
> }
> }
> },
> "props": {
> "showClearIcon": true
> },
> "type": "ia.input.dropdown"
> },
> {
> "meta": {
> "name": "value"
> },
> "position": {
> "basis": "150px"
> },
> "propConfig": {
> "props.text": {
> "binding": {
> "config": {
> "path": "../Dropdown.props.value"
> },
> "type": "property"
> }
> }
> },
> "type": "ia.display.label"
> }
> ],
> "meta": {
> "name": "families"
> },
> "position": {
> "basis": "34px"
> },
> "props": {
> "style": {
> "gap": "3px"
> }
> },
> "type": "ia.container.flex"
> },
> {
> "children": [
> {
> "meta": {
> "name": "Label"
> },
> "position": {
> "basis": "150px"
> },
> "props": {
> "text": "categories"
> },
> "type": "ia.display.label"
> },
> {
> "meta": {
> "name": "Dropdown"
> },
> "position": {
> "basis": "256px"
> },
> "propConfig": {
> "props.options": {
> "binding": {
> "config": {
> "parameters": {
> "family_id": "{.../families/Dropdown.props.value}"
> },
> "queryPath": "sandbox/list_categories"
> },
> "type": "query"
> }
> },
> "props.value": {
> "onChange": {
> "enabled": null,
> "script": "\tself.parent.parent.getChild(\"items\").getChild(\"Dropdown\").props.value \u003d None"
> }
> }
> },
> "props": {
> "showClearIcon": true
> },
> "type": "ia.input.dropdown"
> },
> {
> "meta": {
> "name": "value"
> },
> "position": {
> "basis": "150px"
> },
> "propConfig": {
> "props.text": {
> "binding": {
> "config": {
> "path": "../Dropdown.props.value"
> },
> "type": "property"
> }
> }
> },
> "type": "ia.display.label"
> }
> ],
> "meta": {
> "name": "categories"
> },
> "position": {
> "basis": "34px"
> },
> "props": {
> "style": {
> "gap": "3px"
> }
> },
> "type": "ia.container.flex"
> },
> {
> "children": [
> {
> "meta": {
> "name": "Label"
> },
> "position": {
> "basis": "150px"
> },
> "props": {
> "text": "items"
> },
> "type": "ia.display.label"
> },
> {
> "meta": {
> "name": "Dropdown"
> },
> "position": {
> "basis": "256px"
> },
> "propConfig": {
> "props.options": {
> "binding": {
> "config": {
> "parameters": {
> "category_id": "{.../categories/Dropdown.props.value}"
> },
> "queryPath": "sandbox/list_items"
> },
> "type": "query"
> }
> }
> },
> "props": {
> "showClearIcon": true
> },
> "type": "ia.input.dropdown"
> },
> {
> "meta": {
> "name": "value"
> },
> "position": {
> "basis": "150px"
> },
> "propConfig": {
> "props.text": {
> "binding": {
> "config": {
> "path": "../Dropdown.props.value"
> },
> "type": "property"
> }
> }
> },
> "type": "ia.display.label"
> }
> ],
> "meta": {
> "name": "items"
> },
> "position": {
> "basis": "34px"
> },
> "props": {
> "style": {
> "gap": "3px"
> }
> },
> "type": "ia.container.flex"
> }
> ],
> "meta": {
> "name": "root"
> },
> "props": {
> "direction": "column",
> "style": {
> "gap": "10px",
> "padding": "15px"
> }
> },
> "type": "ia.container.flex"
> }
> }
> 
> ```

and another page used to navigate to it with parameters:

> ****
>
> ```json
> {
> "custom": {},
> "params": {},
> "props": {},
> "root": {
> "children": [
> {
> "children": [
> {
> "meta": {
> "name": "Label"
> },
> "position": {
> "basis": "150px"
> },
> "props": {
> "text": "families"
> },
> "type": "ia.display.label"
> },
> {
> "meta": {
> "name": "Dropdown"
> },
> "position": {
> "basis": "256px"
> },
> "propConfig": {
> "props.options": {
> "binding": {
> "config": {
> "queryPath": "sandbox/list_families"
> },
> "type": "query"
> }
> }
> },
> "props": {
> "showClearIcon": true,
> "value": null
> },
> "type": "ia.input.dropdown"
> }
> ],
> "meta": {
> "name": "families"
> },
> "position": {
> "basis": "34px"
> },
> "type": "ia.container.flex"
> },
> {
> "children": [
> {
> "meta": {
> "name": "Label"
> },
> "position": {
> "basis": "150px"
> },
> "props": {
> "text": "categories"
> },
> "type": "ia.display.label"
> },
> {
> "meta": {
> "name": "Dropdown"
> },
> "position": {
> "basis": "256px"
> },
> "propConfig": {
> "props.options": {
> "binding": {
> "config": {
> "parameters": {
> "family_id": "{.../families/Dropdown.props.value}"
> },
> "queryPath": "sandbox/list_categories"
> },
> "type": "query"
> }
> }
> },
> "props": {
> "showClearIcon": true,
> "value": 9
> },
> "type": "ia.input.dropdown"
> }
> ],
> "meta": {
> "name": "categories"
> },
> "position": {
> "basis": "34px"
> },
> "type": "ia.container.flex"
> },
> {
> "children": [
> {
> "meta": {
> "name": "Label"
> },
> "position": {
> "basis": "150px"
> },
> "props": {
> "text": "items"
> },
> "type": "ia.display.label"
> },
> {
> "meta": {
> "name": "Dropdown"
> },
> "position": {
> "basis": "256px"
> },
> "propConfig": {
> "props.options": {
> "binding": {
> "config": {
> "parameters": {
> "category_id": "{.../categories/Dropdown.props.value}"
> },
> "queryPath": "sandbox/list_items"
> },
> "type": "query"
> }
> }
> },
> "props": {
> "showClearIcon": true,
> "value": null
> },
> "type": "ia.input.dropdown"
> }
> ],
> "meta": {
> "name": "items"
> },
> "position": {
> "basis": "34px"
> },
> "type": "ia.container.flex"
> },
> {
> "events": {
> "component": {
> "onActionPerformed": {
> "config": {
> "params": {
> "category_id": "{/root/categories/Dropdown.props.value}",
> "family_id": "{/root/families/Dropdown.props.value}",
> "item_id": "{/root/items/Dropdown.props.value}"
> },
> "view": "VUES/SUIVI_OUTILLAGE/sandbox/mainpage"
> },
> "scope": "C",
> "type": "nav"
> }
> }
> },
> "meta": {
> "name": "Button"
> },
> "position": {
> "basis": "34px"
> },
> "type": "ia.input.button"
> }
> ],
> "meta": {
> "name": "root"
> },
> "props": {
> "direction": "column",
> "style": {
> "gap": "10px",
> "padding": "15px"
> }
> },
> "type": "ia.container.flex"
> }
> }
> 
> ```

and some queries to create/fill the tables used (MSSQL):

> ****
>
> ```plaintext
> create table families (
> id int identity primary key,
> name nvarchar(50)
> )
> 
> create table categories (
> id int identity primary key,
> family_id int references families (id),
> name nvarchar(50)
> )
> 
> create table items (
> id int identity primary key,
> category_id int references categories (id),
> name nvarchar(50)
> )
> 
> insert into families (name)
> values
> ('familyA'),
> ('familyB'),
> ('familyC'),
> ('familyD')
> 
> insert into categories (name, family_id)
> values
> ('category1A', 1),
> ('category1B', 1),
> ('category1C', 1),
> ('category1D', 1),
> ('category2A', 2),
> ('category2B', 2),
> ('category2C', 2),
> ('category2D', 2),
> ('category3A', 3),
> ('category3B', 3),
> ('category3C', 3),
> ('category3D', 3),
> ('category4A', 4),
> ('category4B', 4),
> ('category4C', 4),
> ('category4D', 4)
> 
> insert into items (name, category_id)
> values
> ('1AA', 1),
> ('1AB', 1),
> ('1AC', 1),
> ('1AD', 1),
> ('1BA', 2),
> ('1BB', 2),
> ('1BC', 2),
> ('1BD', 2),
> ('1CA', 3),
> ('1CB', 3),
> ('1CC', 3),
> ('1CD', 3),
> ('1DA', 4),
> ('1DB', 4),
> ('1DC', 4),
> ('1DD', 4),
> ('2AA', 5),
> ('2AB', 5),
> ('2AC', 5),
> ('2AD', 5),
> ('2BA', 6),
> ('2BB', 6),
> ('2BC', 6),
> ('2BD', 6),
> ('2CA', 7),
> ('2CB', 7),
> ('2CC', 7),
> ('2CD', 7),
> ('2DA', 8),
> ('2DB', 8),
> ('2DC', 8),
> ('2DD', 8),
> ('3AA', 9),
> ('3AB', 9),
> ('3AC', 9),
> ('3AD', 9),
> ('3BA', 10),
> ('3BB', 10),
> ('3BC', 10),
> ('3BD', 10),
> ('3CA', 11),
> ('3CB', 11),
> ('3CC', 11),
> ('3CD', 11),
> ('3DA', 12),
> ('3DB', 12),
> ('3DC', 12),
> ('3DD', 12),
> ('4AA', 13),
> ('4AB', 13),
> ('4AC', 13),
> ('4AD', 13),
> ('4BA', 14),
> ('4BB', 14),
> ('4BC', 14),
> ('4BD', 14),
> ('4CA', 15),
> ('4CB', 15),
> ('4CC', 15),
> ('4CD', 15),
> ('4DA', 16),
> ('4DB', 16),
> ('4DC', 16),
> ('4DD', 16)
> 
> ```

---

<div class="post-metadata">

**Author:** ![j.israelsen](https://avatars.discourse-cdn.com/v4/letter/j/ad7895/32.png) [@j.israelsen](https://forum.inductiveautomation.com/u/j.israelsen)\
**Post date:** [July 3, 2023, 3:01pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/19 "2023-07-03T15:01:41Z")

</div>

I haven't had a chance to look at your sample page, but here was a quick thought on enabling or disabling code. If you had a single function or message handler, perhaps could you could enable function items (like startup versus change of value) with basic IF statements, something like this:

`def update(self):`

```
#Only call if not already updating
if self.custom.updatingFlag == False:
	
	#Startup
	if self.custom.updatingFlag == False and startup:
		self.custom.updatingFlag = True
		#(CODE)
		
	#Update A (Clear B & C)
	if self.custom.updatingFlag == False and updateA:
		self.custom.updatingFlag = True
		#(CODE)
		
	#Update B (Clear C)
	if self.custom.updatingFlag == False and updateB:
		self.custom.updatingFlag = True
		#(CODE)

	#Clear Updating Flag
	self.custom.updatingFlag = False

```

\*Edit, missed a tab.

---

<div class="post-metadata">

**Author:** ![pascal.fragnoud](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pascal.fragnoud/32/24728_2.png) [@pascal.fragnoud](https://forum.inductiveautomation.com/u/pascal.fragnoud)\
**Post date:** [July 3, 2023, 3:56pm UTC](https://forum.inductiveautomation.com/t/controling-bindings-evaluation-order/75842/20 "2023-07-03T15:56:35Z")

</div>

I'm assuming `updateA` and `updateB` are also flags ?  
I envisioned something like this, but as I said I'd like to try to find a simpler solution first.

Not that it's particularly complicated, but I feel like there's a 'better' way.

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