पटलम्:Wikidata

Methods

The module "Wikidata" contains the following methods, that allow the calling script to retrieve the value for any property from Wikidata by supplying the property ID as the first parameter:

• getValue: Returns wiki-linked values, if applicable. All other values will be output similar to {{#property:}}, except that if values with preferred rank exist, then only they are returned.
• getRawValue: Returns non-linked property values and numbers with the thousand separator. All other values will be output similar to {{#property:}}, including normal values, even if preferred values exist.
• getDateValue: Special method to return formatted dates. The default date format is [day month year]; an optional third parameter can be added for other date formats: for [month day, year], add "mdy"; for [month year], add "my"; for year only, add "y". A further optional parameter, which must be fourth, such as "BCE", may be added to override the default "BC" that is suffixed for dates BC.

Wikidata qualifier values (if present) can be retrieved by the following methods:

• getQualifierValue: returns only wiki-linked values, if applicable.
• getRawQualifierValue: returns non-linked values
• getQualifierDateValue: returns formatted dates

If the property is not defined in Wikidata for the article that invokes this code, then an empty string ("") is returned.

Other methods:

• pageId: returns the Wikidata id (Q…) of the current page or nothing if the page is not connected to Wikidata
• getTAValue: gets the TA98 (Terminologia Anatomica first edition 1998) values for property P1323. It takes no parameters and constructs its output as a list, with each value linked to an external resource. This is an exemplar for writing calls that need to return external links.
• ViewSomething: gets anything in the structured data, including labels, descriptions, references and interwiki links. See [१]
• Dump: spies the structured data. It uses the same arguments as ViewSomething. Try this with preview only to see results. That helps you a lot in developing Lua scripts that access the data. If used without arguments, it dumps everything including labels, descriptions, references and interwiki links. See [२]

Parameters

• For the generalized case (getValue), two unnamed parameters are supplied. The first is the ID of the property that is to be retrieved (e.g. P19 for birthplace or P26 for spouse). The second may be null, "FETCH_WIKIDATA", or any other string, which becomes the returned value.
• For the generalized unlinked case (getRawValue), two unnamed parameters are supplied. The first is the ID of the property that is to be retrieved (e.g. P21 for gender). The second may be null, "FETCH_WIKIDATA", or any other string, which becomes the returned value.
• For the generalized date case (getDateValue), three unnamed parameters are supplied. The first is the ID of the property that is to be retrieved (e.g. P569 for date of birth). The second may be null, "FETCH_WIKIDATA", or any other string, which becomes the returned value. The third is the format that the date should be returned in, either dmy, mdy, my, or y.

Please note that lower-case parameters are no longer supported by the wikibase call, so please check that upper-case, like P123, is used if problems should arise.

Usage

Example:spouse

• {{#invoke:Wikidata|getValue|P26|}} = returns nothing, so suppresses the display of spouse in an infobox
• {{#invoke:Wikidata|getValue|P26|FETCH_WIKIDATA}} = returns the linked value(s) of property P26 (spouse) stored in wikidata for the corresponding article (e.g. for article Bill Clinton, it returns Hillary Rodham Clinton)
• {{#invoke:Wikidata|getValue|P26|[[Hillary Clinton]]}} = returns Hillary Clinton, allowing an infobox to use a local value rather than the value stored in Wikidata.

Example in Infobox template

Inside an infobox definition, it may be called like this:

• | data55 = {{#invoke:Wikidata|getValue|P26|{{{spouse|FETCH_WIKIDATA}}} }}

which causes the infobox to:

1. not display spouse if the infobox parameter |spouse is set to be blank (as "| spouse ="}
2. display the linked value(s) from Wikidata if the infobox parameter |spouse is not supplied
3. display the local infobox parameter |spouse if it is supplied (e.g. "|spouse = Hillary Clinton")

Optionally, it could be called as:

• | data55 = {{#invoke:Wikidata|getValue|P26|{{{spouse|}}} }}

which should behave as the parameter does now, unless the parameter is set to FETCH_WIKIDATA when it displays the linked value(s) fetched from Wikidata.

Example:birth place

This works in just the same way as the calls above:

• {{#invoke:Wikidata|getValue|P19|}} = returns nothing, so suppresses the display of birth place in an infobox
• {{#invoke:Wikidata|getValue|P19|FETCH_WIKIDATA}} = returns the linked value(s) of property P19 (place of birth) stored in wikidata for the corresponding article (e.g. for article Bill Clinton, it returns Hope, Arkansas)
• {{#invoke:Wikidata|getValue|P19|[[Hope, Arkansas|Hope]]}} = returns Hope, allowing an infobox to use a local value rather than the value stored in Wikidata.

Example:gender

We don't want the returned value linked, so use:

• - {{#invoke:Wikidata|getRawValue|P21|FETCH_WIKIDATA}}

Example:date of birth

If we want the date of birth in dmy format, we use:

• - {{#invoke:Wikidata|getDateValue|P569|FETCH_WIKIDATA|dmy}}

If we want the date of birth in mdy format, we use:

• - {{#invoke:Wikidata|getDateValue|P569|FETCH_WIKIDATA|mdy}}

If we want a year of birth, we use:

• - {{#invoke:Wikidata|getDateValue|P569|FETCH_WIKIDATA|y}}

If we want a year of birth that may be BC, but should read "BCE", we use:

• - {{#invoke:Wikidata|getDateValue|P569|FETCH_WIKIDATA|y|BCE}}

Example: Linking to Wikidata item

Use the following code to just retrieve the Q-ID:

• - {{#invoke:Wikidata|pageId}}

Linking to Wikidata used the usual Wiki markup:

• - [[d:{{#invoke:Wikidata|pageId}}|Name of Link]]

Testing

Testing spouse

Copy and paste the following into any article and preview it (please don't save!):

* - {{#invoke:Wikidata|getValue|P26|}}
* - {{#invoke:Wikidata|getValue|P26|FETCH_WIKIDATA}}
* - {{#invoke:Wikidata|getValue|P26|[[Hillary Clinton]]}}

In Bill Clinton you should get:

• -
• - Hillary Rodham Clinton
• - Hillary Clinton

In Barack Obama you should get:

• -
• - Michelle Obama
• - Hillary Clinton

In Richard Burton you should get:

• -
• - Sally Burton, Elizabeth Taylor
• - Hillary Clinton

In Franz Kafka you should get:

• -
• -
• - Hillary Clinton

Testing birthplace

Copy and paste the following into any article and preview it (please don't save!):

* - {{#invoke:Wikidata|getValue|P19|}}
* - {{#invoke:Wikidata|getValue|P19|FETCH_WIKIDATA}}
* - {{#invoke:Wikidata|getValue|P19|[[Newport]]}}

Try William Ellery and check that the Wikidata call correctly disambiguates.

Testing getValue, getRawValue and getDateValue

Copy and paste the following into any article and preview it (please don't save!):

* - {{#invoke:Wikidata|getValue|P19|FETCH_WIKIDATA}}
* - {{#invoke:Wikidata|getValue|P26|FETCH_WIKIDATA}}
* - {{#invoke:Wikidata|getValue|P27|FETCH_WIKIDATA}}
* - {{#invoke:Wikidata|getValue|P140|FETCH_WIKIDATA}}
* - {{#invoke:Wikidata|getRawValue|P21|FETCH_WIKIDATA}}
* - {{#invoke:Wikidata|getDateValue|P569|FETCH_WIKIDATA|dmy}}
* - {{#invoke:Wikidata|getDateValue|P569|FETCH_WIKIDATA|mdy}}
* - {{#invoke:Wikidata|getDateValue|P569|FETCH_WIKIDATA|y}}

This should return the Wikidata values for birthplace, spouse, citizenship, religion, gender, date of birth (twice) and year of birth, if they exist. The dob is first in dmy format and then in mdy.

Testing dates BC/BCE

Copy and paste the following into a short section of article such as Horace #See also and preview it (please don't save!):

* - {{#invoke:Wikidata|getDateValue|P569|FETCH_WIKIDATA|y}}
* - {{#invoke:Wikidata|getDateValue|P569|FETCH_WIKIDATA|y|BCE}}

This should return 65 BC and 65 BCE, respectively.

---

require('Module:No globals')

local p = {}

-- module local variables
local wiki = 
{
	langcode = mw.language.getContentLanguage().code
}

-- internationalisation
local i18n = {
    ["errors"] = {
        ["property-not-found"] = "Property not found.",
        ["entity-not-found"] = "Wikidata entity not found.",
        ["unknown-claim-type"] = "Unknown claim type.",
        ["unknown-entity-type"] = "Unknown entity type.",
        ["qualifier-not-found"] = "Qualifier not found.",
        ["site-not-found"] = "Wikimedia project not found.",
    },
    ["datetime"] =
	{
		-- $1 is a placeholder for the actual number
		[0] = "$1 billion years",	-- precision: billion years
		[1] = "$100 million years",	-- precision: hundred million years
		[2] = "$10 million years",	-- precision: ten million years
		[3] = "$1 million years",	-- precision: million years
		[4] = "$100,000 years",		-- precision: hundred thousand years
		[5] = "$10,000 years",		-- precision: ten thousand years
		[6] = "$1  millenium",	 	-- precision: millennium
		[7] = "$1 century",			-- precision: century
		[8] = "$1s",				-- precision: decade
		-- the following use the format of #time parser function
		[9]  = "Y",					-- precision: year, 
		[10] = "F Y",				-- precision: month
		[11] = "F j, Y",			-- precision: day
		[12] = "F j, Y ga",			-- precision: hour
		[13] = "F j, Y g:ia",		-- precision: minute
		[14] = "F j, Y g:i:sa",		-- precision: second
		["beforenow"] = "$1 BCE",	-- how to format negative numbers for precisions 0 to 5
		["afternow"] = "$1 CE",		-- how to format positive numbers for precisions 0 to 5
		["bc"] = '$1 "BCE"',		-- how print negative years
		["ad"] = "$1"				-- how print positive years
	},
	["monolingualtext"] = '<span lang="%language">%text</span>',
	["warnDump"] = "[[Category:Called function 'Dump' from module Wikidata]]"
}

local function printError(code)
	return '<span class="error">' .. (i18n.errors[code] or code) .. '</span>'
end

function p.descriptionIn(frame)
	local langcode = frame.args[1]
	local id = frame.args[2]	-- "id" must be nil, as access to other Wikidata objects is disabled in Mediawiki configuration
	-- return description of a Wikidata entity in the given language or the default language of this Wikipedia site
	return mw.wikibase.getEntityObject(id).descriptions[langcode or wiki.langcode].value
end

function p.labelIn(frame)
	local langcode = frame.args[1]
	local id = frame.args[2]	-- "id" must be nil, as access to other Wikidata objects is disabled in Mediawiki configuration
	-- return label of a Wikidata entity in the given language or the default language of this Wikipedia site
	return mw.wikibase.getEntityObject(id).labels[langcode or wiki.langcode].value
end

-- This is used to get a value, or a comma separated list of them if multiple values exist
p.getValue = function(frame)
	local propertyID = mw.text.trim(frame.args[1] or "")
	local input_parm = mw.text.trim(frame.args[2] or "")
	if input_parm == "FETCH_WIKIDATA" then
		local entity = mw.wikibase.getEntityObject()
		local claims
		if entity and entity.claims then
			claims = entity.claims[propertyID]
		end
		if claims then
			-- if wiki-linked value output as link if possible
			if (claims[1] and claims[1].mainsnak.snaktype == "value" and claims[1].mainsnak.datavalue.type == "wikibase-entityid") then
				local out = {}
				for k, v in pairs(claims) do
					local sitelink = mw.wikibase.sitelink("Q" .. v.mainsnak.datavalue.value["numeric-id"])
					local label = mw.wikibase.label("Q" .. v.mainsnak.datavalue.value["numeric-id"])
					if label == nil then label = "Q" .. v.mainsnak.datavalue.value["numeric-id"] end
							
					if sitelink then
						out[#out + 1] = "[[" .. sitelink .. "|" .. label .. "]]"
					else
						out[#out + 1] = "[[:d:Q" .. v.mainsnak.datavalue.value["numeric-id"] .. "|" .. label .. "]]<abbr title='Article is not yet available in this wiki'>[*]</abbr>"
					end
				end
				return table.concat(out, ", ")
			else
				-- just return best vakues
				return entity:formatPropertyValues(propertyID).value
			end
		else
			return ""
		end
	else
		return input_parm
	end
end

p.getQualifierValue = function(frame)
	local propertyID = mw.text.trim(frame.args[1] or "")
	local qualifierID = mw.text.trim(frame.args[2] or "")
	local input_parm = mw.text.trim(frame.args[3] or "")
	if input_parm == "FETCH_WIKIDATA" then
		local entity = mw.wikibase.getEntityObject()
		if entity.claims[propertyID] ~= nil then
			local out = {}
			for k, v in pairs(entity.claims[propertyID]) do
				for k2, v2 in pairs(v.qualifiers[qualifierID]) do
					if v2.snaktype == 'value' then
						if (mw.wikibase.sitelink("Q" .. v2.datavalue.value["numeric-id"])) then
							out[#out + 1] = "[[" .. mw.wikibase.sitelink("Q" .. v2.datavalue.value["numeric-id"]) .. "]]"
						else
							out[#out + 1] = "[[:d:Q" .. v2.datavalue.value["numeric-id"] .. "|" .. mw.wikibase.label("Q" .. v2.datavalue.value["numeric-id"]) .. "]]<abbr title='Article is not yet available in this wiki'>[*]</abbr>"
						end
					end
				end
			end
			return table.concat(out, ", ")
		else
			return ""
		end
	else
		return input_parm
	end
end

-- This is used to get a value like 'male' (for property p21) which won't be linked and numbers without the thousand separators
p.getRawValue = function(frame)
	local propertyID = mw.text.trim(frame.args[1] or "")
	local input_parm = mw.text.trim(frame.args[2] or "")
	if input_parm == "FETCH_WIKIDATA" then
		local entity = mw.wikibase.getEntityObject()
		local claims
		if entity then claims = entity.claims[propertyID] end
		if claims then
			local result = entity:formatPropertyValues(propertyID, mw.wikibase.entity.claimRanks).value
		
			-- if number type: remove thousand separators
			if (claims[1] and claims[1].mainsnak.snaktype == "value" and claims[1].mainsnak.datavalue.type == "quantity") then
				result = mw.ustring.gsub(result, "(%d),(%d)", "%1%2")
			end
			return result
		else
			return ""
		end
	else
		return input_parm
	end
end

p.getRawQualifierValue = function(frame)
	local propertyID = mw.text.trim(frame.args[1] or "")
	local qualifierID = mw.text.trim(frame.args[2] or "")
	local input_parm = mw.text.trim(frame.args[3] or "")
	if input_parm == "FETCH_WIKIDATA" then
		local entity = mw.wikibase.getEntityObject()
		if entity.claims[propertyID] ~= nil then
			local out = {}
			for k, v in pairs(entity.claims[propertyID]) do
				for k2, v2 in pairs(v.qualifiers[qualifierID]) do
					if v2.snaktype == 'value' then
						if v2.datavalue.value["numeric-id"] then
							out[#out + 1] = mw.wikibase.label("Q" .. v2.datavalue.value["numeric-id"])
						else
							out[#out + 1] = v2.datavalue.value
						end
					end
				end
			end
			local ret = table.concat(out, ", ")
			return string.upper(string.sub(ret, 1, 1)) .. string.sub(ret, 2)
		else
			return ""
		end
	else
		return input_parm
	end
end

-- This is used to get a date value for date_of_birth (P569), etc. which won't
-- be linked -- consolidate by testing if entity.claims[propertyID].mainsnak.datavalue.type
-- is "time". Dates and times are stored in ISO 8601 format.
p.getDateValue = function(frame)
	local propertyID = mw.text.trim(frame.args[1] or "")
	local input_parm = mw.text.trim(frame.args[2] or "")
	local date_format = mw.text.trim(frame.args[3] or "dmy")
	local date_suffix = mw.text.trim(frame.args[4] or "BC")
	if input_parm == "FETCH_WIKIDATA" then
		local entity = mw.wikibase.getEntityObject()
		if entity.claims[propertyID] ~= nil then
			local out = {}
			local dt = {}
			for k, v in pairs(entity.claims[propertyID]) do
				if v.mainsnak.snaktype == 'value' then
					-- check for negative date
					local suffix = ""
					local timestamp = v.mainsnak.datavalue.value.time
					if string.sub(timestamp, 1, 1) == '-' then
						timestamp = '+' .. string.sub(timestamp, 2)
						suffix = " " .. date_suffix
					end
					local function d(f)
						return mw.language.new(wiki.langcode):formatDate(f, timestamp) .. suffix
					end
					if date_format == "mdy" then
						out[#out + 1] = d("F j, Y")
					elseif date_format == "my" then
						out[#out + 1] = d("F Y")
					elseif date_format == "y" then
						-- suppress leading zeros in year
						local stryear = d("Y")
						while string.sub(stryear, 1, 1) == '0' do
							stryear = string.sub(stryear, 2)
						end
						out[#out + 1] = stryear
					else
						out[#out + 1] = d("j F Y")
					end
				end
			end
			return table.concat(out, ", ")
		else
			return ""
		end
	else
		return input_parm
	end
end

p.getQualifierDateValue = function(frame)
	local propertyID = mw.text.trim(frame.args[1] or "")
	local qualifierID = mw.text.trim(frame.args[2] or "")
	local input_parm = mw.text.trim(frame.args[3] or "")
	local date_format = mw.text.trim(frame.args[4] or "dmy")
	if input_parm == "FETCH_WIKIDATA" then
		local entity = mw.wikibase.getEntityObject()
		if entity.claims[propertyID] ~= nil then
			local out = {}
			for k, v in pairs(entity.claims[propertyID]) do
				for k2, v2 in pairs(v.qualifiers[qualifierID]) do
					if v2.snaktype == 'value' then
						local function d(f)
							return mw.language.new(wiki.langcode):formatDate(f, v2.datavalue.value.time)
						end
						if date_format == "mdy" then
							out[#out + 1] = d("F j, Y")
						elseif date_format == "my" then
							out[#out + 1] = d("F Y")
						elseif date_format == "y" then
							out[#out + 1] = d("Y")
						else
							out[#out + 1] = d("j F Y")
						end
					end
				end
			end
			return table.concat(out, ", ")
		else
			return ""
		end
	else
		return input_parm
	end
end

-- This is used to get the TA98 (Terminologia Anatomica first edition 1998) values like 'A01.1.00.005' (property P1323)
-- which are then linked to http://www.unifr.ch/ifaa/Public/EntryPage/TA98%20Tree/Entity%20TA98%20EN/01.1.00.005%20Entity%20TA98%20EN.htm
-- uses the newer mw.wikibase calls instead of directly using the snaks
-- formatPropertyValues returns a table with the P1323 values concatenated with ", " so we have to split them out into a table in order to construct the return string
p.getTAValue = function(frame)
	local ent = mw.wikibase.getEntityObject()
	local props = ent:formatPropertyValues('P1323')
	local out = {}
	local t = {}
	for k, v in pairs(props) do
		if k == 'value' then
			t = mw.text.split( v, ", ")
			for k2, v2 in pairs(t) do
				out[#out + 1] = "[http://www.unifr.ch/ifaa/Public/EntryPage/TA98%20Tree/Entity%20TA98%20EN/" .. string.sub(v2, 2) .. "%20Entity%20TA98%20EN.htm " .. v2 .. "]"
			end
		end
	end
	local ret = table.concat(out, "<br> ")
	if #ret == 0 then
		ret = "Invalid TA"
	end
	return ret
end

-- returns the page id (Q...) of the current page or nothing of the page is not connected to Wikidata
function p.pageId(frame)
	local entity = mw.wikibase.getEntityObject()
	if not entity then return nil else return entity.id end
end

-- the "qualifiers" and "snaks" field have a respective "qualifiers-order" and "snaks-order" field
-- use these as the second parameter and this function instead of the built-in "pairs" function
-- to iterate over all qualifiers and snaks in the intended order.
local function orderedpairs(array, order)
	if not order then return pairs(array) end
 
	-- return iterator function
    local i = 0
    return function()
        i = i + 1
        if order[i] then
            return order[i], array[order[i]]
        end
    end	
end

-- precision: 0 - billion years, 1 - hundred million years, ..., 6 - millennia, 7 - century, 8 - decade, 9 - year, 10 - month, 11 - day, 12 - hour, 13 - minute, 14 - second
local function normalizeDate(date)
	date = mw.text.trim(date, "+")
	-- extract year
	local yearstr = mw.ustring.match(date, "^\-?%d+")
	local year = tonumber(yearstr)
	-- remove leading zeros of year
	return year .. mw.ustring.sub(date, #yearstr + 1), year
end

local function formatDate(date, precision, timezone)
	precision = precision or 11
	local date, year = normalizeDate(date)
	if year == 0 and precision <= 9 then return "" end
 
 	-- precision is 10000 years or more
	if precision <= 5 then
		local factor = 10 ^ ((5 - precision) + 4)
		local y2 = math.ceil(math.abs(year) / factor)
		local relative = mw.ustring.gsub(i18n.datetime[precision], "$1", tostring(y2))
		if year < 0 then
			relative = mw.ustring.gsub(i18n.datetime.beforenow, "$1", relative)
		else
			relative = mw.ustring.gsub(i18n.datetime.afternow, "$1", relative)
		end			
		return relative
	end
 
 	-- precision is decades, centuries and millennia
	local era
	if precision == 6 then era = mw.ustring.gsub(i18n.datetime[6], "$1", tostring(math.floor((math.abs(year) - 1) / 1000) + 1)) end
	if precision == 7 then era = mw.ustring.gsub(i18n.datetime[7], "$1", tostring(math.floor((math.abs(year) - 1) / 100) + 1)) end
	if precision == 8 then era = mw.ustring.gsub(i18n.datetime[8], "$1", tostring(math.floor(math.abs(year) / 10) * 10)) end
	if era then
		if year < 0 then era = mw.ustring.gsub(mw.ustring.gsub(i18n.datetime.bc, '"', ""), "$1", era)
		elseif year > 0 then era = mw.ustring.gsub(mw.ustring.gsub(i18n.datetime.ad, '"', ""), "$1", era) end
		return era
	end
 
 	-- precision is year
 	if precision == 9 then
 		return year
 	end
 
	-- precision is less than years
	if precision > 9 then
		--[[ the following code replaces the UTC suffix with the given negated timezone to convert the global time to the given local time
		timezone = tonumber(timezone)
		if timezone and timezone ~= 0 then
			timezone = -timezone
			timezone = string.format("%.2d%.2d", timezone / 60, timezone % 60)
			if timezone[1] ~= '-' then timezone = "+" .. timezone end
			date = mw.text.trim(date, "Z") .. " " .. timezone
		end
		]]--
 
		local formatstr = i18n.datetime[precision]
		if year == 0 then formatstr = mw.ustring.gsub(formatstr, i18n.datetime[9], "")
		elseif year < 0 then
			-- Mediawiki formatDate doesn't support negative years
			date = mw.ustring.sub(date, 2)
			formatstr = mw.ustring.gsub(formatstr, i18n.datetime[9], mw.ustring.gsub(i18n.datetime.bc, "$1", i18n.datetime[9]))
		elseif year > 0 and i18n.datetime.ad ~= "$1" then
			formatstr = mw.ustring.gsub(formatstr, i18n.datetime[9], mw.ustring.gsub(i18n.datetime.ad, "$1", i18n.datetime[9]))
		end
		return mw.language.new(wiki.langcode):formatDate(formatstr, date)
	end
end

local function printDatavalueEntity(data, parameter)
	-- data fields: entity-type [string], numeric-id [int, Wikidata id]
	local id
	
	if data["entity-type"] == "item" then id = "Q" .. data["numeric-id"]
	elseif data["entity-type"] == "property" then id = "P" .. data["numeric-id"]
	else return printError("unknown-entity-type")
	end
	
	if parameter then
		if parameter == "link" then
			local linkTarget = mw.wikibase.sitelink(id)
			local linkName = mw.wikibase.label(id)
			if linkTarget then
				-- if there is a local Wikipedia article link to it using the label or the article title
				return "[[" .. linkTarget  .. "|" .. (linkName or linkTarget) .. "]]"
			else
				-- if there is no local Wikipedia article output the label or link to the Wikidata object to let the user input a proper label
				if linkName then return linkName else return "[[:d:" .. id .. "|" .. id .. "]]" end
			end
		else
			return data[parameter]
		end
	else
		return mw.wikibase.label(id) or id
	end
end

local function printDatavalueTime(data, parameter)
	-- data fields: time [ISO 8601 time], timezone [int in minutes], before [int], after [int], precision [int], calendarmodel [wikidata URI]
	--   precision: 0 - billion years, 1 - hundred million years, ..., 6 - millennia, 7 - century, 8 - decade, 9 - year, 10 - month, 11 - day, 12 - hour, 13 - minute, 14 - second
	--   calendarmodel: e.g. http://www.wikidata.org/entity/Q1985727 for the proleptic Gregorian calendar or http://www.wikidata.org/wiki/Q11184 for the Julian calendar]
	if parameter then
		if parameter == "calendarmodel" then data.calendarmodel = mw.ustring.match(data.calendarmodel, "Q%d+") -- extract entity id from the calendar model URI
		elseif parameter == "time" then data.time = normalizeDate(data.time) end
		return data[parameter]
	else
		return formatDate(data.time, data.precision, data.timezone)
	end
end

local function printDatavalueMonolingualText(data, parameter)
	-- data fields: language [string], text [string]
	if parameter then
		return data[parameter]
	else
		local result = mw.ustring.gsub(mw.ustring.gsub(i18n.monolingualtext, "%%language", data["language"]), "%%text", data["text"])
		return result
	end
end

local function findClaims(entity, property)
	if not property or not entity or not entity.claims then return end
 
	if mw.ustring.match(property, "^P%d+$") then
		-- if the property is given by an id (P..) access the claim list by this id
		return entity.claims[property]
	else
		property = mw.wikibase.resolvePropertyId(property)
		if not property then return end

		return entity.claims[property]
	end
end

local function getSnakValue(snak, parameter)
	if snak.snaktype == "value" then
		-- call the respective snak parser
		if snak.datavalue.type == "string" then return snak.datavalue.value
		elseif snak.datavalue.type == "globecoordinate" then return printDatavalueCoordinate(snak.datavalue.value, parameter)
		elseif snak.datavalue.type == "quantity" then return printDatavalueQuantity(snak.datavalue.value, parameter)
		elseif snak.datavalue.type == "time" then return printDatavalueTime(snak.datavalue.value, parameter)
		elseif snak.datavalue.type == "wikibase-entityid" then return printDatavalueEntity(snak.datavalue.value, parameter)
		elseif snak.datavalue.type == "monolingualtext" then return printDatavalueMonolingualText(snak.datavalue.value, parameter)
		end
	end
	return mw.wikibase.renderSnak(snak)
end
 
local function getQualifierSnak(claim, qualifierId)
	-- a "snak" is Wikidata terminology for a typed key/value pair
	-- a claim consists of a main snak holding the main information of this claim,
	-- as well as a list of attribute snaks and a list of references snaks
	if qualifierId then
		-- search the attribute snak with the given qualifier as key
		if claim.qualifiers then
			local qualifier = claim.qualifiers[qualifierId]
			if qualifier then return qualifier[1] end
		end
		return nil, printError("qualifier-not-found")
	else
		-- otherwise return the main snak
		return claim.mainsnak
	end
end
 
local function getValueOfClaim(claim, qualifierId, parameter)
	local error
	local snak
	snak, error = getQualifierSnak(claim, qualifierId)
	if snak then
		return getSnakValue(snak, parameter)
	else
		return nil, error
	end
end

local function getReferences(frame, claim)
	local result = ""
	-- traverse through all references
	for ref in pairs(claim.references or {}) do
		local refparts
		-- traverse through all parts of the current reference
		for snakkey, snakval in orderedpairs(claim.references[ref].snaks or {}, claim.references[ref]["snaks-order"]) do
			if refparts then refparts = refparts .. ", " else refparts = "" end
			-- output the label of the property of the reference part, e.g. "imported from" for P143
			refparts = refparts .. tostring(mw.wikibase.label(snakkey)) .. ": " 
			-- output all values of this reference part, e.g. "German Wikipedia" and "English Wikipedia" if the referenced claim was imported from both sites
			for snakidx = 1, #snakval do
				if snakidx > 1 then refparts = refparts .. ", " end
				refparts = refparts .. getSnakValue(snakval[snakidx])
			end
		end
		if refparts then result = result .. frame:extensionTag("ref", refparts) end
	end
	return result
end

function p.claim(frame)
	local property = frame.args[1] or ""
	local id = frame.args["id"]	-- "id" must be nil, as access to other Wikidata objects is disabled in Mediawiki configuration
	local qualifierId = frame.args["qualifier"]
	local parameter = frame.args["parameter"]
	local list = frame.args["list"]
	local references = frame.args["references"]
	local showerrors = frame.args["showerrors"]
	local default = frame.args["default"]
	if default then showerrors = nil end
 
	-- get wikidata entity
	local entity = mw.wikibase.getEntityObject(id)
	if not entity then
		if showerrors then return printError("entity-not-found") else return default end
	end
	-- fetch the first claim of satisfying the given property
	local claims = findClaims(entity, property)
	if not claims or not claims[1] then
		if showerrors then return printError("property-not-found") else return default end
	end
 
	-- get initial sort indices
	local sortindices = {}
	for idx in pairs(claims) do
		sortindices[#sortindices + 1] = idx
	end
	-- sort by claim rank
	local comparator = function(a, b)
		local rankmap = { deprecated = 2, normal = 1, preferred = 0 }
		local ranka = rankmap[claims[a].rank or "normal"] ..  string.format("%08d", a)
		local rankb = rankmap[claims[b].rank or "normal"] ..  string.format("%08d", b)
		return ranka < rankb
 	end
	table.sort(sortindices, comparator)
 
	local result
	local error
	if list then
		local value
		-- iterate over all elements and return their value (if existing)
		result = {}
		for idx in pairs(claims) do
			local claim = claims[sortindices[idx]]
			value, error =  getValueOfClaim(claim, qualifierId, parameter)
			if not value and showerrors then value = error end
			if value and references then value = value .. getReferences(frame, claim) end
			result[#result + 1] = value
		end
		result = table.concat(result, list)
	else
		-- return first element	
		local claim = claims[sortindices[1]]
		result, error = getValueOfClaim(claim, qualifierId, parameter)
		if result and references then result = result .. getReferences(frame, claim) end
	end
 
	if result then return result else
		if showerrors then return error else return default end
	end
end

-- look into entity object
function p.ViewSomething(frame)
	local data = mw.wikibase.getEntityObject()
	if not data then
		return nil
	end

	local f = frame.args[1] and frame or frame:getParent()

	local i = 1
	while true do
		local index = f.args[i]
		if not index then
			if type(data) == "table" then
				return mw.text.jsonEncode(data, mw.text.JSON_PRESERVE_KEYS + mw.text.JSON_PRETTY)
			else
				return tostring(data)
			end
		end
		
		data = data[index] or data[tonumber(index)]
		if not data then
			return
		end
		
		i = i + 1
	end
end

function p.Dump(frame)
	local data = mw.wikibase.getEntityObject()
	if not data then
		return i18n.warnDump
	end

	local f = frame.args[1] and frame or frame:getParent()

	local i = 1
	while true do
		local index = f.args[i]
		if not index then
			return "<pre>"..mw.dumpObject(data).."</pre>".. i18n.warnDump
		end

		data = data[index] or data[tonumber(index)]
		if not data then
			return i18n.warnDump
		end

		i = i + 1
	end
end

return p