8.12. Updating Interchange Database Tables with a Form

Any Interchange database can be updated with a form using the following method. The Interchange user interface uses this facility extensively.

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Note: All operations are performed on the database, not the ASCII source file. An [export table_name] operation will have to be performed for the ASCII source file to reflect the results of the update. Records in any database may be inserted or updated with the [query] tag, but form-based updates or inserts may also be performed.

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In an update form, special Interchange variables are used to select the database parameters:

mv_data_enable (scratch)

\IMPORTANT: This must be set to a non-zero, non-blank value in the scratch space to allow data set functions. Usually it is put in an mv_click that precedes the data set function. For example:

            [set update_database]
            [if type=data term="userdb::trusted::[data session username]"]
                [set mv_data_enable]1[/set]
            [else]
                [set mv_data_enable]0[/set]
            [/else]
            [/if]
            [/set]
            <INPUT TYPE=hidden NAME=mv_click VALUE=update_database>

mv_data_table

The table to update.

mv_data_key

The field that is the primary key in the table. It must match the existing database definition.

mv_data_function

UPDATE, INSERT or DELETE. The variable mv_data_verify must be set true on the form for a DELETE to occur.

mv_data_verify

Confirms a DELETE.

mv_data_fields

Fields from the form which should be inserted or updated. Must be existing columns in the table in question.

mv_update_empty

Normally a variable that is blank will not replace the field. If mv_update_empty is set to true, a blank value will erase the field in the database.

mv_data_filter_(field)

Instantiates a filter for (field), using any of the defined Interchange filters. For example, if mv_data_filter_foo is set to digits, only digits will be passed into the database field during the set operation. A common value might be "entities", which protects any HTML by translating < into &lt;, " into &quot;, etc.

The Interchange action set causes the update. Here are a pair of example forms. One is used to set the key to access the record (careful with the name, this one goes into the user session values). The second actually performs the update. It uses the [loop] tag with only one value to place default/existing values in the form based on the input from the first form:

   <FORM METHOD=POST ACTION="[process]">
    <INPUT TYPE=HIDDEN name="mv_doit" value="return">
    <INPUT TYPE=HIDDEN name="mv_nextpage" value="update_proj">
    Sales Order Number <INPUT TYPE=TEXT SIZE=8
                            NAME="update_code"
                            VALUE="[value update_code]">
    <INPUT TYPE=SUBMIT name="mv_submit"  Value="Select">
    </FORM>
<FORM METHOD=POST ACTION="[process]">
   <INPUT TYPE=HIDDEN NAME="mv_data_table"    VALUE="ship_status">
   <INPUT TYPE=HIDDEN NAME="mv_data_key"      VALUE="code">
   <INPUT TYPE=HIDDEN NAME="mv_data_function" VALUE="update">
   <INPUT TYPE=HIDDEN NAME="mv_nextpage"      VALUE="updated">
   <INPUT TYPE=HIDDEN NAME="mv_data_fields"
               VALUE="code,custid,comments,status">
   <PRE>

   [loop arg="[value update_code]"]
   Sales Order <INPUT TYPE=TEXT NAME="code    SIZE=10 VALUE="[loop-code]">
  Customer No. <INPUT TYPE=TEXT NAME="custid" SIZE=30
                   VALUE="[loop-field custid]">
      Comments <INPUT TYPE=TEXT NAME="comments"
                   SIZE=30 VALUE="[loop-field comments]">
        Status <INPUT TYPE=TEXT NAME="status"
                   SIZE=10 VALUE="[loop-field status]">
   [/loop]
   </PRE>

       <INPUT TYPE=hidden NAME="mv_todo" VALUE="set">
       <INPUT TYPE=submit VALUE="Update table">
   </FORM>

The variables in the form do not update the user's session values, so they can correspond to database field names without fear of corrupting the user session.

8.12.1. Can I use Interchange with my existing static catalog pages?

Yes, but you probably won't want to in the long run. Interchange is designed to build pages based on templates from a database. If all you want is a shopping cart, you can mix standard static pages with Interchange, but it is not as convenient and doesn't take advantage of the many dynamic features Interchange offers.

That being said, all you usually have to do to place an order link on a page is:

   <A HREF="/cgi-bin/construct/order?mv_order_item=SKU_OF_ITEM">Order!</A>

Replace /cgi-bin/construct with the path to your Interchange link.

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Copyright 2002-2004 Interchange Development Group. Copyright 2001-2002 Red Hat, Inc. Freely redistributable under terms of the GNU General Public License.