Power Platform Community Forum Thread Details

Hello

I have been searching with no solution found. My aim is to create a Canvas Power App that will host a complex decision tree. The backend will be Dataverse as the solution will have internal tenant users and guest access users.

I have tried to indicate part of the decision ask below. Each question is multiple choice, Y/N, or more complex.

What I have tried to show is that the decision question can lead to further questions.

I have considered to tackle this using collections and a gallery. So the gallery used for A, B, C is filled by those questions in the collection based on the decision question/answer.

Ignoring for now A.1, my challenge at the moment is that the questions in A/ B, C can vary, but the multiple choice answers can vary. I know I can put a drop down in a gallery, but how would I fill each drop down if it can change?

Or am I over complicating this and there is a easier solution, approach?

Thank you for any help you can provide, even if just a suggestion to help me refine my search for an answer.

Regards

Stuart

Categories:

Building Power Apps

Hi,

You’re not over-complicating it. It's totally doable in Canvas Apps. You should not hard-code your questions or dropdown values. You can store them in Dataverse. Below would be my approach that I would use and it should work even for complex trees.

You can have your:

Questions stored as records
Answers stored as records
Logic stored as relationships, not formulas

Table 1: Question

Column	Type	Purpose
QuestionId	GUID	Primary key
QuestionText	Text	What is shown
QuestionType	Choice	Yes/No, MultipleChoice, Number, Text
ParentQuestionId	Lookup (Questions)	Which question led here
ParentAnswerId	Lookup (Answers)	Which answer triggers this question
DisplayOrder	Number	Order in gallery
IsActive	Yes/No	Control visibility

A question will appears only if its' parent answer was selected.

Table 2: Answer

Column	Type	Purpose
AnswerId	GUID	Primary key
QuestionId	Lookup (Questions)	Which question it belongs to
AnswerText	Text	Dropdown / radio value
NextQuestionGroup	Optional	Advanced branching
Value	Text/Number	Optional scoring

Each question can have any number of answers.

Table 3: UserResponse

Column	Type
User	User / Email
QuestionId	Lookup
AnswerId	Lookup
SessionId	GUID

This will allow you to track questions and answers for each user and you can use SessionId for guest users.

Canvas app UI pattern (This solves your dropdown problem)

Single gallery (vertical)

galQuestions.Items:

Filter(
    Questions,
    IsActive = true &&
    (
        IsBlank(ParentQuestionId) ||
        ParentAnswerId in colUserAnswers.AnswerId
    )
)

With this:

Root questions show first
Child questions appear only after parent answer is selected

Dynamic Answer Controls (The Key Insight)

Use one control per question type, not per question

Inside the gallery use:

Switch(
    ThisItem.QuestionType,
    "YesNo", radYesNo,
    "MultipleChoice", drpMulti,
    "Text", txtAnswer,
    "Number", txtNumber
)

Only the matching control will be visible.

How each dropdown will get its own answers

I think this is the part you were stuck on.

Dropdown inside gallery, use:

Items = Filter(
    Answers,
    QuestionId = ThisItem.QuestionId
)

With this:

Each row gets different answers
No collections required
Fully data-driven

To capture the answers

Use something this OnChange of dropdown/radio then new questions appear automatically.

Collect(
    colUserAnswers,
    {
        QuestionId: ThisItem.QuestionId,
        AnswerId: drpMulti.Selected.AnswerId
    }
)

To handle deep trees like (A → A.1 → A.1.a)

You will have it with table setup because:

Each question references to a parent answer
Depth won't matter
No recursion will be needed

Hope this helps!

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