Lua/Frame Object

Lua modules based on the Scribunto/Lua extension are stored in resource pages using the Module: namespace. Each module uses a table to hold functions and variables, and that containing table is returned at the end of the module code. This lesson will show you how to use the Lua Frame object in your scripts.

Prerequisites

This lesson assumes you have already completed the Tables lesson.

Create a Lua Script that Uses the Frame Object

To create a Lua script that uses the Frame object:

1. Navigate to Module:Sandbox.
2. Clear all existing code.

   It's a sandbox. Everyone is free to play in the sandbox. But if you find another user is actively editing the sandbox at the same time, you may also use Module:Sandbox/Username, where Username is your Wikiversity username.

3. Add the following code and save the page:

local p = {}

local function tableToString(t)
    local key
    local value
    local result
 
    result = ''
 
    for key, value in pairs(t) do
        if (tonumber(key) ~= nil) then
            result = result .. ':table[' .. key .. '] is ' .. value .. '\n' 
        else
            result = result .. ':table[\'' .. key .. '\'] is ' .. value .. '\n' 
        end
    end
 
    return result
end
 
function p.args(frame)
    return ';args\n' .. tableToString(frame.args)
end

function p.callParserFunction(frame)
    return ';callParserFunction\n:' .. frame:callParserFunction('#time', 'Y-m-d H:i:s') .. '\n'
end

function p.expandTemplate(frame)
    return ';expandTemplate\n:' .. frame:expandTemplate({title = 'Template:Sandbox', args = {'arg1', 'arg2'}}) .. '\n'
end

function p.extensionTag(frame)
    return ';extensionTag\n:' .. frame:extensionTag('nowiki', '[[text]]', {}) .. '\n'
end

function p.getParent(frame)
	frame = frame:getParent()
    return ';getParent\n:' .. frame:getTitle() .. '\n'
end

function p.getTitle(frame)
    return ';getTitle\n:' .. frame:getTitle() .. '\n'
end

return p

Test Your Lua Script

To test your Lua script:

1. Navigate to either the Module_talk:Sandbox page, the Wikiversity:Sandbox page, or your own user or sandbox page.
2. Add the following code and save the page:

{{#invoke:Sandbox|args|These|are|arg3=frame args.}}
{{#invoke:Sandbox|callParserFunction}}
{{#invoke:Sandbox|expandTemplate}}
{{#invoke:Sandbox|extensionTag}}
{{#invoke:Sandbox|getParent}}
{{#invoke:Sandbox|getTitle}}

The result should be similar to:

args

table[1] is These

table[2] is are

table['arg3'] is frame args.

callParserFunction

2013-12-20 02:20:13

expandTemplate

2

extensionTag

[[text]]

getParent

Module talk:Sandbox

getTitle

Module:Sandbox

Understand Your Lua Script

To understand your Lua script:

1. local function tableToString(t) declares a local function named tableToString that accepts a single parameter t, which is the table to be converted to a string.

   See Lua/Tables for more information.

2. function p.args(frame) declares a function named args which accepts a single parameter frame, which is the interface to the calling object.
   • frame.args is a table of arguments passed to the function.
   • Positional arguments are accessed by numeric position.
   • Named arguments are accessed by name.
3. frame:callParserFunction('#time', 'Y-m-d H:i:s') calls the parser function #time, passing the string literal 'Y-m-d H:i:s' to display the current time.
4. frame:expandTemplate({title = 'Template:Sandbox', args = {'arg1', 'arg2'}}) calls the Template:Sandbox template, passing a table of parameter arguments and returns the result.
5. frame:extensionTag('nowiki', '[[text]]', {}) tags the given text to control processing when the text is returned to the calling object.
6. frame:getParent() returns the parent of the calling object, or in this case the page that invoked the module.
7. frame:getTitle() returns a string containing the title of the frame.

Conclusion

Congratulations! You've now created, tested, and understood a Lua script that uses the Frame object. Return to the main Lua page to learn about other Lua code libraries.

See Also

• Lua Tables

References

← Table Library

Lua

Title Library →