Signature

This component is used to capture a signature that is drawn by the user. The content can be enlarged (displayed in a popup window) by selecting the expand button in the top right corner, the field can also be cleared by selecting the X in the bottom right corner.

Component Code

The first section of the code region contains the standard parameters and variables needed for the component to function.

OnParametersSetAsync()

This method is called when the component first loads or there is an update to its parent component. Its purpose is to assign values to the components variables using the field definition.

ValueChanged(string newValue)

This method is called when the value of the signature field changes. Its purpose is to update the ValueUX variable with the new value and validate the value. If the value is valid then ChangeXML() is called.

ChangeXML()

This method is called by ValueChanged(). Its purpose is to create XML and add it to the instances data changes to be saved.

Below is an example of the XML structure that is saved to the instance.

<XMLName>
    John Doe On 2023-01-12 20:17:03 UTC
    <Signee>John Doe</Signee>
    <SignedOn>2023-01-12 20:17:03</SignedOn>
    <SignatureB64>The Base64 string of the signature</SignatureB64>
</XMLName>

IMPORTANT NOTE: The value of the signature is a Base64 string (an image). Given that Base64 strings contain thousands of characters this data is only stored in the InstanceData field in the database. Views, etc will display the value of the XMLName element from from the example above. If you need to access the Base64 data of the signature you will need to get it from the InstanceData column.

Updated on June 3, 2024

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