PDF XFA FILL FORM

A solution you can investigate is using the PDFFormField class which would allow you to supply such a value to an existing field. Here is a sample you can test with:

static List EditFormFields(List editedFields) 
{ 
    foreach (var field in editedFields) 
    { 
        if (field.ContentType == PDFFormField.ContentTypeUnrestrained) 
        { 
            field.Contents = new List { "Input String" }; 
        } 
    } 
 
    return editedFields; 
} 

https://www.leadtools.com/help/sdk/tutorials/dotnet-console-parse-edit-and-save-pdf-form-fields.html

To set a value for an XFA DateTime field using Spire.Pdf in C#, you should use the XfaDateTimeField.XfaValue property instead of Value. Here's the corrected code:

case "form1[0].DDEEInput[0].EaxmCompletedDate[0]":
    XfaDateTimeField xfSCompleteDate = xfaField as XfaDateTimeField;
    xfSCompleteDate.XfaValue = "12/05/2020";
    break;
Using XfaValue should correctly set the date in your XFA DateTime field.

Hey, Ameer bhai how would have you overcome this datefiled issue can you tell me