Generating Form Field Variable name programmatically and set a value to it

I am using a Single Record Form
I have a AJAX custom Button called LoadValues
In the PHP segment of the LoadValues button if I put {m_dsr_month} = ‘January’;, by clicking the button the Form Field m_dsr_month gets the value ‘January’ and also shows it on the form

But my requirement is slightly different.
I have a form called form_user_log which has columns like , user_name, , u_log_month, scriptcase generated
This form has 2 fields user_name, u_log_month.

I have an an excel file which has 2 columns u_name and u_month.

I have a mySql table called userlog_excelcolumns with all the field names from the user_log table and column letters from the excel file . So the table has column tblFields = u_log_month.against which will be column letter ‘B’ as in the Excel Table. Same for the user_name which will have Column Letter “A”
Now the AJAX button will have to do the following

  1. Read the Excel File data
  2. Based on the column being read, look up the userlog_excelcolumns table matching the column Letter, get the column tblFields Value in to php Variable generated_form_field.
  3. Set the Form Field similar to the generated_form_field
    For example
    Step 2 returns u_log_month. Then I have to set the value read from Excel into Form Field {u_log_month}.
    Step 1 and 2 is working fine
    Step 3 works only if I use a condition statement like
    if generated_form_field == ‘u_log_month’ {u_log_month} = excelValue;
    But again, i am using a for loop, the excel has 44 columns , the for loop iterates each column. So I want to generate the Field Name and set value instead of using 44 IF statements
    Can some one help
    Tried Code

$form_fields = $this->nmgp_dados_form; // Create an array $form_fields of all the fields in the form
$form_fields[strtolower($fieldName)] = $value;