Lua templating/Snippets

This page contains some quick lua snippets to help create modules.

## General

Get template and transcluding page arguments

```
local p = {}
function p.doStuff(frame)
        local transclusionArguments = frame.args
        local templateArguments = frame:getParent().args
        local templateOption = templateArguments["option"] or ""
        local transclusionOption = transclusionArguments["trans\_option"] or ""

        return transclusionOption .. templateOption
end

return p

```

Check if a lua table contains values.

```
local tTab = {}
if next(tTab) then
    mw.log (true)
end

```

Get the title of the page that transcludes a page containing a lua invocation (parent frame). This is typically a template name.

```
local p = {}
function p.frameTitle(frame)
    local title = frame:getParent():getTitle()
    return (title)
end
return p

```

Get parameters (`bool=` in example) passed to template that have no value and read them to set boolean variables (or just `localBool` in this example).

```
local p = {}

-- include Arguments module at dev.wikia.com
local getArgs = require('Dev:Arguments').getArgs

function p.myTemplate(frame) -- Implements {{myTemplate}}
	local args = getArgs(frame, {
	trim = false,
	removeBlanks = false -- Keeps empty params
	})
	local booleanVar = false -- Default booleanVar to false

	-- Set booleanVar to true if |bool= used with template
	if args["bool"] then
		booleanVar = true
	end

	return p.\_myTemplate(args, booleanVar)
end

function p.\_myTemplate( args, isBool )
	local localBool = isBool -- Set local boolean variable
	local returnWikitext = nil

	-- Do stuff that is conditional on isBool and set returnWikitext

	return returnWikitext
end

```

## Text

Find a piece of text within text.

```
local textToFind = "one"
local content = "In the end there can be only one"
local startposition , endposition = string.find(content, textToFind)

if startposition then
   mw.log (true)
end

```

Show only a specific number of sequential tokens (group of characters) from a piece of text.

```
local text  = "Human beings are a disease, a cancer of this planet."
local tab = mw.text.split( text, " ")
local tokens = 5
local output = ""
   for i= 0, tokens do
       output = output .. " " .. (tab[i] or "")
   end

print(output)

```

```
Output : Human beings are a disease,
```

## Math

Round a number.

```
function p.round(num, idp)
    local roundedNumber = tonumber(string.format("%." .. (idp or 0) .. "f", num))

    return (roundedNumber)
end

```

## Date

Add days to a date.

```
local iDays = 50
local iDayToSecs = iDays  \* 24 \* 60 \*60
local timestamp = os.time({month=12,year=2012,day=10})
local futureDate = os.date("%Y-%m-%d", timestamp + iDayToSecs)

mw.log (futureDate)

```

## Conditional statements

Using a ternary operator.

```
local condition = true
local trueText = "Bananas are good"
local returnText = condition and trueText or ""
--This returns trueText if condition is true, and "" if not
mw.log (returnText)

```

## Sorting

Sorting using an Associative table

```
function spairs(t, order)
    -- collect the keys
    local keys = {}
    for k in pairs(t) do keys[#keys+1] = k end

    -- if order function given, sort by it by passing the table and keys a, b,
    -- otherwise just sort the keys
    if order then
        table.sort(keys, function(a,b) return order(t, a, b) end)
    else
        table.sort(keys)
    end

    -- return the iterator function
    local i = 0
    return function()
        i = i + 1
        if keys[i] then
            return keys[i], t[keys[i]]
        end
    end
end

```

Usage

```
local power = { Majin = "11", Buu = "3", Baba = "10" , ["5"] = "ratty", ["8"] = "bum"   }

-- basic usage, just sort by the keys
for k,v in spairs(power) do
    print(k,v)
end
--Sorts by keys
--Output
--5 ratty 8 bum Baba 10 Buu 3 Majin 11
-- Sort by values
for k,v in spairs(power, function(t,a,b) return t[b] < t[a] end) do
    print(k,v)
end
-->5 ratty
-->8 bum
-->Buu 3
-->Majin 11
-->Baba 10

```

## See also

* Module:Stats
* Lua templating/Converting Wikitext templates

## References

1. ↑ Sort a Table[] in Lua. http://stackoverflow.com/a/15706820