Access a Collection property Dynamically with Variable

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Posted on 12 Apr 2022 07:33:55 by Community Power Pla...

Hi Power Platform Community, do you know if it is possible to access a collection property dynamically in power apps?

I have the following myMonth property that I want to use to dynamically access the value of a property.

and accessing it simply gives me an error like this:

I am basically trying to reproduce a transposed table.

Happy for any workaround to being introduced. Thank you.

Regards,

Rico.

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Using Apps Using Formulas

Connecting to Data

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BostonSailor 150 on 07 Sep 2024 at 15:48:21

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Access a Collection property Dynamically with Variable

You can't in Power Apps, but you can in Power Automate. I face this often when a custom connector returns a JSON dictionary rather than a JSON array.

SampleArray:

[

{"Key": "ABCD", "Value": 1},

{"Key": "EFGH", "Value": 2}

]

SampleDictionary:

{

"ABCD":

{"Value": 1},

"EFGH":

{"Value": 2}

}

To find a value in the array, I might:

LookUp(SampleArray, Key="ABCD").Value

If the key I want is a constant, then I could do this in the dictionary:

SampleDictionary.ABCD.Value

But let's say the key I want is a string variable called MyKey. I might want to say:

SampleDictionary.MyKey.Value // That surely won't work

LookUp(SampleDictionary, Key=MyKey).Value // That won't work either, as the dictionary is not a table

In desperation, I end up writing a short Power Automate flow, passing the dictionary (or whatever) into the flow as a JSON string.

After whatever massaging is needed to create Compose actions with my dictionary and my key, I can then use an expression like this:

Outputs('SampleDictionary')?[Outputs('MyKey')]

and get value(s) from that as...

Outputs('SampleDictionary')?[Outputs('MyKey')]?['Value']

If you haven't already, it may require a new learning curve to get familiar with Power Automate (whose language bears no resemblance to Power Fx). But as far as I know it's the only way to do it.
WarrenBelz 147,126 Most Valuable Professional on 16 Apr 2022 at 05:41:53

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Re: Access a Collection property Dynamically with Variable

@Anonymous ,

If you want confirmation on @C-Papa 's explanation of dynamic referral of Power Apps elements such as Field, List or Control names, then it is absolutely correct - you simply cannot do it.
Community Power Pla... on 12 Apr 2022 at 09:31:33

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Re: Access a Collection property Dynamically with Variable

Thank you so much for your detailed suggestion and explanation.
I will take this into consideration. Have a great day.
C-Papa 1,836 on 12 Apr 2022 at 09:29:21

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Re: Access a Collection property Dynamically with Variable

In that case i think you are unlikely to get an app that works for them through PowerApps. By doing it the way i suggested you will still get the correct data, it will also allow you to filter much better and your table will not be so large. you have to remember that if your table is growing in columns year on year you will get to a point where its not useable. i can't see this being a scalable approach.

if you google "powerapps select column dynamically" you will see lots of threads where this has previously been talked about. Good luck
Community Power Pla... on 12 Apr 2022 at 09:19:12

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Re: Access a Collection property Dynamically with Variable

Thanks for your suggestion.

But this is the business requirements, they want to be able to add a new month as a column.

Regards,
Rico.
C-Papa 1,836 on 12 Apr 2022 at 09:17:12

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Re: Access a Collection property Dynamically with Variable

You can't pass the column name dynamically into the function. you would need to use the If or Switch function to change the formula for all of the months, but this isn't really scalable. I would have probably done it a bit differently by having a "Date" column rather than a new column for every year. This would allow you to filter the database based on a date and return the values you need, which would all be in one column. Concat() would then work as expected.
Community Power Pla... on 12 Apr 2022 at 08:59:01

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Re: Access a Collection property Dynamically with Variable

Thanks for your suggestion. I tried something like you suggested, but still not getting the right value.

Basically, I want to get this value:

But I am getting the following value instead:
Is there anything that I did wrong.
I tried without the Text function too.
C-Papa 1,836 on 12 Apr 2022 at 08:22:53

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Re: Access a Collection property Dynamically with Variable

hi, you need to use the Concat() function to do this. something like Concat(Table1,Text(myMonth,"dd-mm-yyyy"),", ")