Re^3: Going between XML and Cgi by way of DTD

OK, I should have known I'd be challenged.

Here's my thinking. Although XML is often used for traditional two-dimensional row-and-column data, it doesn't have to be. It can have arbitrary levels of nestedness, extra dimensions.

So if you take this XML

<items>
    <item>
        <foo>a</foo>
        <bar>b</bar>
        <baz>c</baz>
    </item>
    <item>
        <foo>x</foo>
        <bar>y</bar>
        <baz>z</baz>
    </item>
</items>
[download]

which follows this DTD:

<!ELEMENT bar (#PCDATA)>
<!ELEMENT baz (#PCDATA)>
<!ELEMENT foo (#PCDATA)>
<!ELEMENT item (foo, bar, baz)>
<!ELEMENT items (item+)>
[download]

Yes, it's pretty much plain sailing to generate the HTML.

But what about this?

<items>
    <item>
        <foo>a</foo>
        <bar>b</bar>
        <baz>c</baz>
        <item> <!-- items can contain sub-items -->
            <foo>d</foo>
            <bar>e</bar>
            <baz>f</baz>
        </item>
    </item>
    <item>
        <foo>x</foo>
        <bar>y</bar>
        <baz>z</baz>
    </item>
</items>
[download]

Which matches the DTD with one small change:

<!ELEMENT bar (#PCDATA)>
<!ELEMENT baz (#PCDATA)>
<!ELEMENT foo (#PCDATA)>
<!ELEMENT item (foo, bar, baz, item?)>
<!ELEMENT items (item+)>
[download]

What's my HTML form going to look like when any given <item> element can contain an arbitrary number of other <item> elements?

Nobody says perl looks like line-noise any more
kids today don't know what line-noise IS ...

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Re^4: Going between XML and Cgi by way of DTD by throop (Chaplain) on Aug 27, 2007 at 03:53 UTC
There are two intertwined challenges here: (1) Generating an display/editing form that corresponds precisely to the XML and the DTD. (2) Rendering this in a way that it makes sense visually to the user. I think I can do that for your example: <html><body> <table border=1 cellspacing=0 cellpadding=3> <caption>Items</caption> <tr><td rowspan=6>Item1</td><td colspan=2>foo:</td><td>a</td></tr> <tr><td colspan=2>bar:</td><td>b</td></tr> <tr><td colspan=2>baz:</td><td>c</td></tr> <tr><td rowspan=3>Item2</td><td>foo:</td><td>d</td></tr> <tr><td>bar:</td><td>e</td></tr> <tr><td>baz:</td><td>f</td></tr> <tr><td rowspan=3>Item3</td> <td colspan=2>foo: </td><td>x</td></tr> <tr><td colspan=2>bar:</td><td>y</td></tr> <tr><td colspan=2>baz:</td><td>z</td></tr> </body></html> [download] (If you download this into a scratch.html file, and view the result in your browser, you'll see better what I'm doing here.) Some tricks here - you've got to traverse the whole tree before you start generating the table – you've got to know what the maximum depth is. You make the table that many columns wide. And you have to know how many leaf elements there are within each item, so you know how many rows tall to make its block. I've previously generated HTML tables to represent structures nested 10 levels deep, with on the order of 200 elements. The nesting is a bit of a problem, but one I've solved previously.	[reply] [d/l]
Re^5: Going between XML and Cgi by way of DTD by Cody Pendant (Prior) on Aug 27, 2007 at 04:12 UTC
I take your point, but you're creating HTML based on my data -- I never said that wasn't possible! How would you create an HTML form based on the DTD? Nobody says perl looks like line-noise any more kids today don't know what line-noise IS ...	[reply]
Re^6: Going between XML and Cgi by way of DTD by pajout (Curate) on Aug 27, 2007 at 15:31 UTC
Let we are in situation, when xml document (or its stub) is on the server and user wants to edit it. Consequently, the application can use both (current) document and (static) DTD for creating web form - in other words, the web form have to be created dynamicaly, according to current data and some validation schema.	[reply]