From Multi Theft Auto: Wiki
Jump to: navigation, search

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.

Almost any data types can be passed as expected, including elements and complex nested tables. Non-element MTA data types like xmlNodes or resource pointers will not be able to be passed as they do not necessarily have a valid representation on the client. Elements of the Vector or Matrix classes cannot be passed!

Events are sent reliably, so the server will receive them, but there may be (but shouldn't be) a significant delay before they are received. You should take this into account when using them.

Keep in mind the bandwidth issues when using events - don't pass a large list of arguments unless you really need to. It is marginally more efficient to pass one large event than two smaller ones.

[[|link=]] Warning: You should use the global variable client serverside instead of passing the localPlayer by parameter or source. Otherwise event faking (passing another player instead of the localPlayer) would be possible. More information at addEventHandler


bool triggerServerEvent ( string event, element theElement, [arguments...] )

Required Arguments

  • event: The name of the event to trigger server-side. You should register this event with addEvent and add at least one event handler using addEventHandler.
  • theElement: The element that is the source of the event.
[[{{{image}}}|link=]] Note: To save server CPU, you should avoid setting theElement to the root element where possible. Using resourceRoot is usually sufficient if the event is handled by the same resource on the server.

Optional Arguments

  • arguments...: A list of arguments to trigger with the event. You can pass any lua data type (except functions). You can also pass elements.


Returns true if the event trigger has been sent, false if invalid arguments were specified or a client side element was a parameter.


This example shows how you can pass a simple "Hello World" message from the client to the server using an event.

Click to collapse [-]
function greetingHandler ( message )
	-- the predefined variable 'client' points to the player who triggered the event and should be used due to security issues   
	outputChatBox ( "The client says: " .. message, client )
addEvent( "onGreeting", true )
addEventHandler( "onGreeting", resourceRoot, greetingHandler ) -- Bound to this resource only, saves on CPU usage.
Click to collapse [-]
function greetingCommand ( commandName )
    triggerServerEvent ( "onGreeting", resourceRoot, "Hello World!" )
    -- Source can be this resource as it saves on CPU and prevents event name conflicts with other resources but you can't use resourceRoot if another resource will handle the event.
addCommandHandler ( "greet", greetingCommand )

When the command "greet" is executed (by typing it in the server console or the player's console), the clients greetingCommand function is called. This triggers the server-side event onGreeting with the string "Hello World!". This event is then handled by the greetingHandler function server-side which then displays the message.

See Also