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Script Blazor

This project adds the ability to write razor components with scripting languages. It supports both Blazor server and wasm.

Note: This is a work in progress. There will be tons of bugs. I am trying to improve it recently.

TRY IT YOURSELF ==> https://acaly.github.io/ScriptBlazor/

Why script?

There are mainly 2 reasons that drive me to write this library:

  • Change razor component without recompiling and publishing the entire app.
  • Execute razor component code in a sandboxed environment.

Combining these, it will be able to allow user of the website to upload highly customized UI elements for themselves.

Design

Although Blazor is a new and complicated technology, a razor component itself is actually very simple. This library compiles a code-mixed HTML file into a script that generates a function for the BuildRenderTree method of the ComponentBase class (the base class of all razor components).

There is some basic abstraction in this library that theoretically allows one, given a proper implementation, to write razor components in any programming language. However, being an extremely simple, fast, and safe language, Lua is definitely the best option.

It depends on MoonSharp to run Lua on top of C# (even in wasm environment).

How to use

The library provides a LuaComponent class, which accepts a parameter of CompiledLuaComponent, which can be generated by LuaBlazorCompiler.Compile method.

There is an example on https://acaly.github.io/ScriptBlazor/ . The code showed initially is

@code
    local x = 0
    function self:test_func()
        return "Hello, Blazor!"
    end
    local function reset()
        x = 0
    end
end
<div style="height:250px;width:200px;border:solid 1px black;color:green;padding:20px">
    <div class="p-2">@self:test_func()</div>
    <div class="p-2">x = @x</div>
    <button class="px-3 m-2 btn btn-primary" @onclick="function() x = x + 1 end">+1</button>
    <button class="px-3 m-2 btn btn-primary" @onclick="function() x = x - 1 end">-1</button>
    @if (x % 2) == 0 then
        <button class="px-3 m-2 btn btn-warning" @onclick="reset">RESET</button>
    end
</div>

The Lua code generated from it is similar to (added indentation)

return function()
    local self = {}
    
    local x = 0
    function self:test_func()
        return "Hello, Blazor!"
    end
    local function reset()
        x = 0
    end
    
    function self:build(__builder0)
        __builder0.AddMarkupContent(0, "\n")
        __builder0.OpenElement(1, "div")
        __builder0.AddAttribute(2, "style", "height:250px;width:200px;border:solid 1px black;color:green;padding:20px")
        __builder0.AddMarkupContent(3, "\n    ")
        __builder0.OpenElement(4, "div")
        __builder0.AddAttribute(5, "class", "p-2")
        __builder0.AddContent(6, self:test_func())
        __builder0.CloseElement()
        __builder0.AddMarkupContent(7, "\n    ")
        __builder0.OpenElement(8, "div")
        __builder0.AddAttribute(9, "class", "p-2")
        __builder0.AddMarkupContent(10, "x")
        __builder0.AddMarkupContent(11, " ")
        __builder0.AddMarkupContent(12, "=")
        __builder0.AddMarkupContent(13, " ")
        __builder0.AddContent(14, x)
        __builder0.CloseElement()
        __builder0.AddMarkupContent(15, "\n    ")
        __builder0.OpenElement(16, "button")
        __builder0.AddAttribute(17, "class", "px-3 m-2 btn btn-primary")
        __builder0.AddAttribute(18, "onclick", function() x = x + 1 end)
        __builder0.AddMarkupContent(19, "+")
        __builder0.AddMarkupContent(20, "1")
        __builder0.CloseElement()
        __builder0.AddMarkupContent(21, "\n    ")
        __builder0.OpenElement(22, "button")
        __builder0.AddAttribute(23, "class", "px-3 m-2 btn btn-primary")
        __builder0.AddAttribute(24, "onclick", function() x = x - 1 end)
        __builder0.AddMarkupContent(25, "-")
        __builder0.AddMarkupContent(26, "1")
        __builder0.CloseElement()
        __builder0.AddMarkupContent(27, "\n    ")
        if (x % 2) == 0 then
            __builder0.OpenElement(28, "button")
            __builder0.AddAttribute(29, "class", "px-3 m-2 btn btn-warning")
            __builder0.AddAttribute(30, "onclick", reset)
            __builder0.AddMarkupContent(31, "RESET")
            __builder0.CloseElement()
            __builder0.AddMarkupContent(32, "\n")
        end
        __builder0.CloseElement()
    end
    return self
end