Examples -- Example 3a: genstory

Example 3a: genstory

The following example script provides two request procedures. The first procedure returns an HTML page for collecting a few fields of data from the user. The second procedure utilizes the data to generate a short story.

This example can be found in the examples/tcl/genstory.tcl file.

    
    # Example 3a: Form generation and handling
    #
    # Two functions are registered. One generates and
    # returns an HTML form, and the other processes
    # the data in the form.
    #
    # Things to notice:
    #
    # * Different functions are registered to the same
    #   URL with different methods.  Note that some browsers
    #   do not cache results properly when you do this.
    #
    # * The genstory function returns an error status
    #   (500) if the client doesn't pass in any form data.
    #
    # * Form data is stored in an ns_set, and accessed
    #   like any other set (e.g., header data).
    #
    # * A counter is used to loop through all the key
    #   value pairs in the form.
    
    ns_register_proc GET /example/genstory genstoryform
    ns_register_proc POST /example/genstory genstory
    
    proc genstoryform {conn context} {
      ns_return $conn 200 text/html \
    "<HTML>
    <HEAD>
    <TITLE>Automatic Story Generator</TITLE>
    </HEAD>
    <BODY>
    <H1>
    Automatic Story Generator
    </H1>
    <FORM ACTION=http:/example/genstory
    METHOD=POST>
    Noun: <INPUT TYPE=text NAME=noun1><BR>
    Noun: <INPUT TYPE=text NAME=noun2><BR>
    Name: <INPUT TYPE=text NAME=name1><BR>
    Name: <INPUT TYPE=text NAME=name2><BR>
    Adjective: <INPUT TYPE=text NAME=adjective1><BR>
    Adjective: <INPUT TYPE=text NAME=adjective2><BR>
    Verb: <INPUT TYPE=text NAME=verb1><BR>
    Verb: <INPUT TYPE=text NAME=verb2><BR>
    <P><INPUT TYPE=submit VALUE=\"Generate\">
    </FORM>
    <P>
    </BODY></HTML>
    "}
    
    proc genstory {conn ignore} {
      set formdata [ns_conn form $conn]
    
      if {$formdata == ""} {
        ns_return $conn 200 text/plain "Need form data!"
        return
      }
    
      # Build up a human-readable representation of the form data.
    
      set hrformdata "<dl>"
      set size [ns_set size $formdata]
      for {set i 0} {$i < $size} {incr i} {
        append hrformdata "<dt>[ns_set key $formdata $i]</dt>\
         <dd>[ns_set value $formdata $i]</dd>"
      }
      append hrformdata "</dl>"
    
      ns_return $conn 200 text/html \
    "<HTML>
    <HEAD>
    <TITLE>The story of [ns_set get $formdata name1] and
    [ns_set get $formdata name2]</TITLE>
    </HEAD>
    <BODY>
    <H1>
    The story of [ns_set get $formdata name1] and
    [ns_set get $formdata name2]
    </H1>
    <P>Once upon a time [ns_set get $formdata name1] and
    [ns_set get $formdata name2] went for a 
    walk in the woods looking for a [ns_set get $formdata noun1].
    [ns_set get $formdata name1] was 
    feeling [ns_set get $formdata adjective1] because
    [ns_set get $formdata name2] was so
    [ns_set get $formdata adjective2].  So
    [ns_set get $formdata name1] decided to
    [ns_set get $formdata verb1] [ns_set get $formdata name2]
    with a [ns_set get $formdata noun2].  This made
    [ns_set get $formdata name2] [ns_set get $formdata verb2]
    [ns_set get $formdata name1].
    <P><CENTER>The End</CENTER>
    The form data that made this possible:<BR>
    $hrformdata
    </BODY></HTML>"
    }

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