This page covers some of the absolute basics for developing a simple lua template.
Basics
Before starting with lua templates, it is important to read up and get to know how to use regular wikitext templates, and preferably read/learn about lua in sites such as Wikibooks as well as reviewing Lua Reference manual.
Workspace
Lua templates are always stored in the Module namespace, and all work must always be saved there. For example, a module named helloworld would be stored in Module:Helloworld.
Creating a module
A module must always contain a table and a line containing a "return " for that table.
--Table
local p = {}
-- code goes here
return p
For a module to be invoked (or used in a page), it needs to have a function. However, this function must be part of the main table (e.g. invocable):
--Table
local invocable = {}
--can be invoked
function invocable.greet(frame)
return "Live long and prosper"
end
-- can't be invoked
function askname(frame)
return "What's your name?"
end
return invocable
Using input (parameters)
Input (or Template parameters) can be provided to a module during the invoke:
{{#invoke:modulename|functioname|input1|input2|input3|...}}
Once the above code is executed a table (called frame) is created containing all those inputs, and it is passed to a function, and stored in a subtable called args (e.g. frame.args). For example, using the invoke below will make use of the module:
{{#invoke:invocable|greet|john}}
{{#invoke:invocable|greet|name=john}}
--Module:Invocable
--Table
local invocable = {}
function invocable.greet(frame)
local name = frame.args[1] or frame.args["name"]
return "Live long and prosper " ..name
end
return invocable
Output : Live long and prosper john
Explanation : Args is a list containing all parameters, args[1] refers to the first value, e.g. john, args["name"] accesses a named parameter "name".
Accessing template input
The invoke above cannot be used through a template because the values from a page, and a sub-page are kept separate. Those arguments can be accessed from a template by first retrieving the parent frame or table containing the arguments (i.e. frame.getParent()), and then using the sub-table (frame:getParent().args):
Template:Greet:
{{#invoke:invocable|greet}}
Module:Invocable:
--Table
local invocable = {}
function invocable.greet(frame)
local parent = frame.getParent()
local name = parent.args[1]
local name2 = parent.args[2] or ""
return "Live long and prosper :" ..name ..' '..name2
end
return invocable
Usage:
{{greet|Jack}}
Output:Live long and prosper : Jack
{{greet|Jack|Jill}}
Output:Live long and prosper : Jack , Jill
| Example | Parameter | Template | Module | Output |
|---|---|---|---|---|
| {{greet|john}} | 1 | {{{1}}} | frame.getParent().args[1] | Live long and prosper john |
| {{greet|name=Spock}} | name | {{{name}}} | frame.getParent().args["name"] | Live long and prosper Spock |
| {{#invoke:invocable|greet|john}} | 1 | frame.args[1] | john | |
| {{#invoke:invocable|greet|name=Worf}} | name | frame.args["name"] | Worf | |
| {{#invoke:invocable|greet|jack|jill}} | 1,2 | frame.args[1],
frame.args[2] |
Live long and prosper : Jack Jill |
Debug console
See Debug console.