<function name="IsValid" parent="Entity" type="classfunc"> <description> Returns whether the entity is a valid entity or not. An entity is valid if: * It is not a [NULL](/gmod/Global_Variables) entity * It is not a <page text="NULL">Global_Variables</page> entity * It is not the worldspawn entity (<page>game.GetWorld</page>) Instead of calling this method directly, it's a good idea to call the global <page>Global.IsValid</page> instead. It will check whether the given variable contains an object (an Entity) or nothing at all for you. See examples. <warning>NULL entities can still be assigned with key/value pairs, but they will be instantly negated. See example 3</warning> This might be a cause for a lot of headache. Usually happening during networking etc., when completely valid entities suddenly become invalid on the client, but are never filtered with IsValid(). See <page>GM:InitPostEntity</page> for more details. </description> <realm>Shared</realm> <rets> <ret name="" type="boolean">true if the entity is valid, false otherwise</ret> </rets> </function> <example> <description>Shows how to use the global <page>Global.IsValid</page> function instead of using this method directly.</description> <code> if ( entity &amp;&amp; entity:IsValid() ) then -- Do stuff end -- The above can be replaced with the following for the same effect (and cleaner code) if ( IsValid( entity ) ) then -- Do stuff end </code> </example> <example> <code>print( LocalPlayer():IsValid() )</code> <output>Outputs 'true' to the console if the player is in-game.</output> </example> <example> <code> local newPlayer = net.ReadEntity() --server found a new player on the server and sent it to us after print( "1/4" ) -- it determined it was valid (newPlayer is NULL in this realm) if not isnumber(newPlayer.ImportantGameData) then --If it doesn't have a specific field, assign a value to it print( "2/4" ) newPlayer.ImportantGameData = 42 end print( "3/4" ) print( newPlayer.ImportantGameData * 69 ) --Attempting to do arithmetics on the new field print( "4/4" ) </code> <output> 1/4 ... 3/4 * A lua error telling us 'ImportantGameData' is a nil value and thus can't perform math on it ---- But this shouldn't be possible, because we just created a value there. No red flags are present up until this point; all code up until this will run fine. Make sure to add an IsValid() check when the seemingly impossible happens. </output> </example>