[Gambas-user] Use gambas WebPages as general-purpose template engine
sharon at 455.co.il
Tue Sep 19 11:35:54 CEST 2023
Is there an example file?
---------- Original Message -----------
From: Martin Fischer <martin.fischer6 at web.de>
To: Gambas Mailing List <user at lists.gambas-basic.org>
Sent: Tue, 19 Sep 2023 10:49:22 +0200
Subject: [Gambas-user] Use gambas WebPages as general-purpose template engine
> Hi fellow gambassins,
> I created a demo project that uses gambas WebPages as general-purpose
> template engine (means: it does not target web-pages, but just
> I know that there has been interest in adding a template-engine to
> gambas (at least, there is a merge request for it). Maybe this would at
> least be worth to be included as sample-project or so.
> Here is the readme of the sample project:
> ### Use Gambas WebPages as templates
> WebPages are designed to be used in the context of web-applications.
> As it turns out, they can also be used as general-purpose template engine
> (with some limitations that I will explain below).
> #### The model
> This sample uses a simple demo model consisting of a list of persons
> This model is made globally available in the module 'MainTemplateModel'
> for a template
> to access and render it (it is not possible to pass a model to a WebPage
> as constructor argument).
> #### The main template
> The template named 'MainTemplate' is responsible for rendering the
> model. It uses static text and
> gambas code to do this.
> Note that it is possible to use all syntactic constructs defined in
> [Gambas WebPage](https://gambaswiki.org/wiki/doc/webpage)
> but constructs that do html-escape before printing something might not
> be adequate for
> your use-case. This means that if you do not want to rendere a html
> document with your template,
> avoid the `<%=expression%>` syntax because that will apply html excaping
> before printing.
> Instead use a block of code like so: `<%Print expression;%>`
> #### Usage of sub-templates
> The MainTemplate delegates the rendering of person birthday to a
> sub-template called
> 'BirthdateTemplate'. It passes the person's birthdate (a Date object) as
> argument to this sub-template.
> Within the BirthdateTemplate, you can access the arguments value by
> accessing the `_Arg` collection
> The runtime puts all arguments passed to a sub-page into this
> collection, keyed by the name of the
> argument (as used in the calling page)
> Note that you might also use the bang-syntax `<%!argName%>` in the
> The problem is that it is not possible to manipulate the arguments value
> with this syntax.
> In our example one param named 'birthdate' is passed to the
> BirthdateTemplate which is of type Date.
> We want to extract only the date-part of it and format it like so:
> `<%Print Format(_Arg["birthdate"], "dd.mm.yyyy");%>`
> Is this case you can not use the bang-syntax. Use a code-block with a
> Print inside (like above).
> Note that there is a problem here: by accessing the `_Arg` collection,
> we break encapsulation.
> The name of this collection is an implementation detail of the WebPage
> machinery. It might change
> without notice in future versions of gambas. Unfortunately, it's the
> only way to avoid the
> very restrictive bang-syntax at the moment.
> I think WebPages are quite usable as general-purpose template engine.
> BUT: usage of the _Arg collection in sub-templates might be a
> show-stopper (read the last paragraph of the readme again...).
> What do you think?
> Does all this make sense to you?
> Martin Fischer
> ----[ http://gambaswiki.org/wiki/doc/netiquette ]----
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