PowerApps Signature Input Issue – PenInput JSON Patch Error

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Posted on by Seth18

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Hi everyone,

I’m trying to implement a “Sign In” and “Sign Out” signature process in my PowerApp, and I’m running into an issue when updating an existing record.

Scenario

Sign In Screen
- I have a form (Form1_1) used for registration.
- I replaced the signature DataCardValue with a PenInput control.
- On the submit button, I capture the signature as JSON:
Set( VarBlob, JSON( InputSignature.Image, JSONFormat.IncludeBinaryData ) ); If( Form1_1.Valid, SubmitForm(Form1_1); ResetForm(Form1_1) );
- The DataCard Update property uses VarBlob.
- This works correctly and stores the Sign In signature in SharePoint.

Sign Out Screen
- This screen uses a Gallery to select an existing registered record.
- The form (Form2) is initially in View mode.
- The user clicks an Edit button → this changes Form2 to Edit mode.
- For the Sign In signature (Image control), I display it correctly using:
Substitute(ThisItem.Signature, """", "")

Adding the Sign Out signature
- I added another PenInput for the Sign Out signature.
- I used similar logic to capture the signature:
Set( VarBlob2, JSON( PenInput1.Image, JSONFormat.IncludeBinaryData ) ); SubmitForm(Form2);
- The Update property of the SignOut Signature DataCard uses VarBlob2

The Problem

When I click the submit button, Form2 fails to save.

I receive an “Invalid Patch” or data type error.

It seems the PenInput JSON is not being accepted when updating an existing item through a form.

May i know how to fix this?

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WarrenBelz 151,895 Most Valuable Professional on at

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PowerApps Signature Input Issue – PenInput JSON Patch Error

Hi @Seth18,

Why not simply make the Update of the Data Card for the second signature PenInput1.Image ? SharePoint and multiple image columns can be temprimental at thimes, but this should work.

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Seth18 131 on at

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PowerApps Signature Input Issue – PenInput JSON Patch Error

Hi @WarrenBelz,

Even tho i make the change on the update code of the datacard it still yet shown this error.

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WarrenBelz 151,895 Most Valuable Professional on at

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PowerApps Signature Input Issue – PenInput JSON Patch Error

Hi @Seth18,

I think there is something else wrong here - assuming that

PenInput1 has an image on it when Form2 is submitted

The Update of the Data Card containing the Image type column is PenInput.Image

The DataSource of your Form is the correct SharePoint List

The Item of your Form is the record to be written to

The Form is in Edit mode

then it should write to SharePoint list - I have also tested it successfully here.

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Seth18 131 on at

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PowerApps Signature Input Issue – PenInput JSON Patch Error

Hi @WarrenBelz,

Thank you for your response. I tried to dig into the issue step by step, and I focused on the date and time datacard in the new modern form. What I noticed is that even when I try to manually enter the date and time for the user checking out (without using the “sign in” or “sign out” signatures), the same error still appears and the form does not submit.

I think I’ve found the cause of the problem, but I’m not completely sure how to fix it.

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WarrenBelz 151,895 Most Valuable Professional on at

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PowerApps Signature Input Issue – PenInput JSON Patch Error

Hi @Seth18,

From your screenshot, you have a Date Picker and two drop-downs for the Hour and Minute for the 'Time Out' field. What is the Update of the Data Card these controls are in ?

You may need to do some debugging here and remove the Update from all but one of the Data Cards (you can comment it out) at a time to see which one is failing.

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