Martin Slachta
24 lines
1.9 KiB
Markdown
24 lines
1.9 KiB
Markdown
# Templating
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Templates allow to replace place values of symbols in text written in one language. Templating itself requires a language. Therefore the process combines two languages.
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This plugin uses templates for success messages of forms & emails. The usage might expand in the future. That is one of the quality attributes of this requirement.
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## Language
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As both use cases are using HTML (one is an email and another a webpage), the templates in this plugin also uses HTML. The frontend for HTML is `RsvHtmlTemplateParser`, that transforms it into an internal structure. The input language can be changed by writing a new frontend for the compiler in the future.
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The main advantage of HTML is that it can be easily extended with custom elements. But we do note that traditional custom elements using JS cannot be used, because JS would not work like that in emails for example.
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Extensions and the plugin itself can register custom elements to templates, for example `<reservation-summary>` that auto-expands onto a nice summary of the selected time slots.
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Atomic values and strings can be retrieved from submitted data using JSON Path RFC using this syntax: `{{ path }}`. The reason for JSON Path is the simplicity of implementation. We are careful not to overcomplicate the templating language, for a price of being less powerful. Helm language being the example of what not to do.
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The language can be easily validated for symbols existence and validity.
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## Custom elements
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The Templating module calls `rsv-template-register-custom-elements` to register custom elements to templates. Plugins can subscribe to it and in the handler register their own custom elements.
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Custom element has a symbol table with values in the input and outputs string. If the custom element has attributes, like `<custom-element attr="test">`, the symbol `attr` with value `test` will also be added to the symbol table.
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