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This function triggers an event previously registered on the server. This is the primary means of passing information between the client and the server. Servers have a similar triggerClientEvent function that can do the reverse. You can treat this function as if it was an asynchronous function call, using triggerClientEvent to pass back any returned information if necessary.

Note

It is marginally more efficient to pass one large event than two smaller ones.

Important

You should use the global variable client server-side instead of passing the localPlayer by parameter or source. Otherwise event faking (passing another player instead of the localPlayer ) would be possible. For more information see: Script security article.

Important

To save server CPU, you should avoid setting theElement to the root element where possible - it should be used as a last resort (rather questionable thing to do, limited to very specific tasks, if any). Using localPlayer is preferred and highly advisable. resourceRoot can also be used as alternative choice, if addEventHandler is bound to root element, or to resourceRoot when there is need to restrict event to single certain resource (although cheater could still trigger it from different resource, by using getResourceRootElement and passing respective resource root element)

Syntax

 triggerServerEvent ( )

Code Examples

Example 1 Example 2 Example 3 Example 4

client

function sendMessageToServer()
  local messageToSend = "Hello, world!" -- this string would be passed to server

  triggerServerEvent("onServerSendMessage", localPlayer, messageToSend) -- refer to the note on wiki page (under theElement), for understanding which element you should use as 2nd argument
end
addCommandHandler("message", sendMessageToServer)

client

function onServerSendMessage(sentMessage)
  if (not client) then -- 'client' points to the player who triggered the event, and should be used as security measure (in order to prevent player faking)
    return false -- if this variable doesn't exists at the moment (for unknown reason, or it was the server who triggered this event), stop code execution
  end

  local matchingSource = (source == client) -- check whether source element (2nd argument in triggerServerEvent) passed from client was the exact same player

  if (not matchingSource) then -- apparently it wasn't
    return false -- so do not process this event
  end

  local dataType = type(sentMessage) -- check type of data coming from client
  local dataString = (dataType == "string") -- check whether it's string

  if (not dataString) then -- if it isn't string
    return false -- stop our code here
  end

  local minStringLength = 1 -- min allowed length of string
  local maxStringLength = 64 -- max allowed length of string
  local stringLength = utf8.len(sentMessage) -- get string length
  local allowedStringLength = (stringLength >= minStringLength and stringLength <= maxStringLength) -- verify whether length is allowed

  if (not allowedStringLength) then -- if string length was exceeded
    return false -- tell server to stop here
  end

  local playerName = getPlayerName(client) -- get name of player who sent message
  local chatMessage = playerName.." sent message from client: "..sentMessage

  outputChatBox(chatMessage, root, 255, 255, 255, false) -- output text sent from client-side for everyone on server

  -- useful utility for checking event data: https://wiki.multitheftauto.com/wiki/Script_security
end
addEvent("onServerSendMessage", true) -- 2nd argument should be set to true, in order to be triggered from counter side (in this case client-side)
addEventHandler("onServerSendMessage", root, onServerSendMessage)

client

function sendTableToServer()
  local tableToSent = {1, 2, 3} -- this table would be passed to server

  triggerServerEvent("onServerSendTable", resourceRoot, tableToSent) -- refer to the note on wiki page (under theElement), for understanding which element you should use as 2nd argument
end
addCommandHandler("table", sendTableToServer)

client

function onServerSendTable(sentTable)
  if (not client) then -- 'client' points to the player who triggered the event, and should be used as security measure (in order to prevent player faking)
    return false -- if this variable doesn't exists at the moment (for unknown reason, or it was the server who triggered this event), stop code execution
  end

  local matchingSource = (source == resourceRoot) -- check whether source element (2nd argument in triggerServerEvent) passed from client was resourceRoot

  if (not matchingSource) then -- apparently it wasn't
    return false -- so do not process this event
  end

  local dataType = type(sentTable) -- check type of data coming from client
  local dataTable = (dataType == "table") -- check whether it's table

  if (not dataTable) then -- if it isn't table
    return false -- stop our code here
  end

  local minTableLength = 1 -- min allowed length of table
  local maxTableLength = 3 -- max allowed length of table
  local tableLength = (#sentTable) -- get table length
  local matchingTableLength = (tableLength >= minTableLength and tableLength <= maxTableLength) -- verify whether length is allowed

  if (not matchingTableLength) then -- if table length was exceeded
    return false -- tell server to stop here
  end

  local numbersOnly = true -- variable which will hold whether numbers only were in the table

  for _, numberValue in pairs(sentTable) do -- iterate through table
    local valueType = type(numberValue) -- check type of each data
    local numberType = (valueType == "number") -- check whether it's a number

    if (not numberType) then -- it isn't a number
      numbersOnly = false -- since at least one of data inside isn't number, set it to false
      break -- break the loop, no need to check further
    end
  end

  if (not numbersOnly) then -- it isn't numbers only table
    return false -- stop code execution
  end

  local playerName = getPlayerName(client) -- get name of player who sent message
  local sentNumbers = table.concat(sentTable, ", ") -- convert our table into list of numbers separated by comma
  local chatMessage = playerName.." sent table with numbers from client: "..sentNumbers

  outputChatBox(chatMessage, root, 255, 255, 255, false) -- output numbers sent from client-side for everyone on server

  -- useful utility for checking event data: https://wiki.multitheftauto.com/wiki/Script_security
end
addEvent("onServerSendTable", true) -- 2nd argument should be set to true, in order to be triggered from counter side (in this case client-side)
addEventHandler("onServerSendTable", resourceRoot, onServerSendTable)

See Also

Event Functions

• addEvent
• addEventHandler
• cancelEvent
• cancelLatentEvent
• getCancelReason
• getEventHandlers
• getLatentEventHandles
• getLatentEventStatus
• removeEventHandler
• triggerClientEvent
• triggerEvent
• triggerLatentClientEvent
• triggerLatentServerEvent
• triggerServerEvent
• wasEventCancelled

Reference

• Scripting Functions