Tech Notes

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Code example: lookup on primary key and display record

In WebHub, there are many ways to position the database cursor on a particular record. The technique described here is a do-it-yourself approach that works in all versions of WebHub.

In this example, the surfer is asked to enter two pieces of information, their social security number ("SSN") (which we presume to be unique) and their bank loan number. The intended result is additional information about their account from the database.

Typical HTML that would go in the page definitions

<whpage pageid="search">
<!--The "result" in the next line refers to the following page name-->
<form method="post" action="(~ACTIONR|result~)">
<!--The "loan_number" in the next line refers to the db field-->
Your Loan Number: <input type="text" name="loan_number" /><br/> 
Your Account Number: <input type="text" name="account" /><br>
<input type="submit" />
</form>
</whpage>

<whpage pageid="result">
(~requires|loan_number|pgError~)
<h2>result of search</h2>
(~evLocateRecord=%
(~field|webdatasource1|last_payment~)
(~field|webdatasource1|date_received~)
(~field|webdatasource1|current_interest~)
</whpage>

<whpage pageid="pgError">
<h2>You must enter your bank loan number!</h2>
</whpage>

Delphi Code:

procedure TForm1.WebDemoAppEventMacro(Sender: TwhRespondingApp; const aMacro,
  aParams, aID: string);
var
  loanNum: String;
begin
  { 1. assume that only one event macro is used, i.e. aMacro = evLocateRecord
    2. assume that Table1 is the dataset pointed to by webdatasource1
  }
  with table1 do 
  begin
    if NOT Active then 
	  Open;
    loanNum := pWebApp.StringVar['Loan_Number'];
    // HTML validates the loan number as a required field
    if NOT FindKey([loanNum]) then 
	begin
      //findkey only works on primary key
      raise Exception.Create('Invalid loan number: '+loanNum);  // A15 *
    end;
    if FieldByName('account').asString <> pWebApp.StringVar['account'] then
      raise Exception.Create('Loan# does not match your account number');
    end;
end;

contributed by Ann Lynnworth on 05-Aug-2007

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