<FORM METHOD="post" ACTION="http://localhost/scripts/chapter6.dll/form"> Name:<br><input type="text" name="NAME_FIELD"><br> SurName:<br><input type="text" name="SURNAME_FIELD"><br> <input type="submit" name="Submit" value="Submit"><br> <input type="reset" name="reset" value="Reset"> </FORM>

(Note that I have taken tags like Font Face, Paragraph, etc out do make it simple).

First, let's take a look at the form tag. It indicates that the information is going to be submitted via POST method. It then tells what action it's going to call (this is basically the same actions that your application consists of). In this case, it's going to call the action "form" of our "chapter6.dll". Next we have the fields that the form contains. The first one is of type TEXT and is called NAME_FIELD. The next one is called SURNAME_FIELD. Lastly, there are two buttons. The first one is the one that actually submits the information contained in the form to the action specified. The second one just resets the form.

IMPORTANT: Only one Submit is performed per form. Note that the actual action isn't associated with the SUBMIT button, but with the FORM. You can never make a form submit to two different places with just plain HTML. There are ways to do this with JavaScript and it's should be quite simply (I'm not going to get into that right now though).

So, what has all this got to do with the ContentFields property we were talking about? Well, the ContentFields property actually contains all the information that is in the form. Let's take a look at our next example program. This example makes use of the ContentFields property to extract the name and surname and create a response that contains the phrase: "Hello Name Surname, how are you doing today?".

Let's look at the code:

Response.Content := 'Hello '+ Request.ContentFields.Values['NAME_FIELD'] + ' ' + Request.ContentFields.Values['SURNAME_FIELD'] + ' how are you today?';

Well, that looks easy. As you can see, to retrieve the values of an HTML form field, all you need to do is access the stringlist of values of the ContentFields, indicating the name you have the field in the HTML form.

Of course, this works with TEXT fields. What about things like a CHECKBOX. Again, this is quite simple. When you post a form that contains a checkbox to your application, if the box is ticked (checked), the value will be in the ContentFields. If it is not checked, then the field won't even be contained in the ContentFields. For example, if you have a CHECKBOX named Tick1:

to actually see if the form was posted with the checkbox ticked, you could do something like: if Request.ContentFields.IndexOfName('Tick1') <> -1 ..... We will examine the ContentFields with more detail in later chapters when we need to make use of the properties. This is just a small sample to show you how to access the fields.

QueryFields
But what about a URL like: 'http://localhost/scripts/chapter6b.dll/action?proto=http&target=www.borland.com? This is what a GET looks like. To access the parameters of the call you would use the QueryFields and NOT the ContentFields.

Let's take a look at the code for this example.

...
if (Request.QueryFields.Values['proto'] = 'http') or
   (Request.QueryFIelds.Values['proto'] = 'ftp') then

if Request.QueryFields.Values <> '' then

   Response.SendRedirect
        (Request.QueryFields.Values['proto'] + '://' +
   Request.QueryFields.Values['target'])
...

We'll examine the SendRedirect method in the next chapter. The idea here is to see how to access the QueryFields values. Again as with the ContentFields you can use the Values property indicating the name of the field. All this action does is re-direct the call to the URI specified.To run the example, open your browser and type different URI's. Make sure you have the DLL copied to the correct location.

We will examine more properties of the TWebRequest object in later chapter, as we need them.

   Methods
I am not going to go into too much detail about the Methods of the TWebRequest. I have hardly ever needed to use any of them. However, I have occassionaly used two, so I'll quickly tell you about these. For more information, refer to the on-line Delphi help.

GetFieldByName
As you saw with the Properties, there are a number of HTTP headers the the TWebRequest handles (such as PathInfo, Host, etc). You might want to one day have access to a certain HTTP header that is not available to you through this properties. To do so, you can use the GetFieldByName method.

ReadClient
As great and easy to use as the ContentFields are, they have their restrictions. The main one is that the Content is limited in size. You can only retrieve contents of up to 48K. Past this value, you need to use the ReadClient function to get access to additional data. This could be used for example when you want to create an application to upload files via the web to your server.

The basic methods and properties needed to start doing some serious applications are covered now. In the next chapter I'll examine the TWebResponse object.