Transferring parameters between the client and the server (TransferringParametersBetweenClientAndServer)

Type	Scope	Severity	Activated by default	Minutes to fix	Tags
Code smell	BSL OS	Major	Yes	2	badpractice performance standard

Description

When transferring control from the client to the server (and vice versa), copies of the parameters are always transferred.

• When a server procedure or function is called from the client, a copy of the actual parameter is created and this copy is passed to the server side.

• When control is returned from the server to the client, a copy of the formal parameter (which was handled in the called procedure or function) is also created for transfer back to the client.

If a formal parameter is specified with the Val modifier, then the value of the parameter will only be passed when the procedure or function is called and will not be passed back when control returns to the client.

Possible scenarios:

• If a structure with nested structures is passed from the client method to the server method without the Val modifier, and the parameter does not change inside the server method, then a copy of this structure with all its attachments will be transferred from the server when control returns.
• In the case of transferring a flat collection that does not change, for example, an array, a copy of this collection will also be returned from the server to the client in vain.

As a result, the absence of the Val modifier in client-server interaction can lead to performance degradation and unnecessary/unnecessary load both by the client and the server.

The current rule finds server methods that execute from client methods and throws remarks on parameters without the Val modifier that are not set to a value.

Examples

1. An example with passing parameters from the client to the server without "Val" and with "Val"

&AtServerNoContext
Procedure TransferParametersToServer(Param1, Val ParamWithVal, Collection, Val CollectionWithVal)

Param1 = "Changed1";
ParamWithVal = "Changed2";
Collection.Insert("Key1", "Changed1");
CollectionWithVal.Insert("Key2", "Changed2");

EndProcedure

&AtClient
Procedure PassingParameters(Command)

Param1 = "Initial1";
ParamWithVal = "Initial2";
Collection = New Structure("Key1", "Source1");
CollectionWithVal = New Structure("Key2", "Source2");

PassingParametersToServer(Param1, ParamWithVal, Collection, CollectionWithVal);

Template = "after server %1 = <%2>";

Message(StrTemplate(Template, "Param1", Param1));
Message(StrTemplate(Template, "ParamWithVal", ParamWithVal));
Message(StrTemplate(Template, "Collection.Key1", Collection.Key1));
Message(StrTemplate(Template, "CollectionWithVal.Key2", CollectionWithVal.Key2));

EndProcedure

This code, when executed, will show the following result

after server Param1= <Changed1>
after server ParamWithVal= <Initial2>
after server Collection.Key1 =  <Changed1>
after server CollectionWithVal.Key2= <Initial2>

It can be seen that all parameters passed through Value do not change their values after execution, incl. and values within collections.

1. An example of inaccurate parameter transfer

   &AtClient
   Procedure UserGroupsDragNDropFinish(Response, AdditionalParameters)
   
   If Response = DialogReturnCode.No Then
   Return;
   EndIf;
   
   MessageToUser = MoveUserToNewGroup(
   AdditionalOptions.DragNDropOptions,
   AdditionalParameters.String,
   AdditionalParameters.Move
   );
   
   EndProcedure
   
   // input parameters ArrayUsers and other parameters do not change
   // and therefore there is no point in additionally returning them from the server
   &AtServer
   Function MoveUserToNewGroup(ArrayUsers, NewGroupOwner, Move)
   
   If NewGroupOwner = Undefined Then
   Return Undefined;
   EndIf;
   
   CurrentGroupOwner = Items.UserGroups.CurrentRow;
   MessageToUser = UsersService.MovingUserToNewGroup(
   ArrayUsers, CurrentGroupOwner, NewGroupOwner, Move);
   
   Items.UsersList.Update();
   Items.UserGroups.Refresh();
   
   Return MessageToUser;
   
   EndFunction
   

Sources

• Article on 1C:ITS - Call with transfer of control from client to server

Snippets

Diagnostic ignorance in code

// BSLLS:TransferringParametersBetweenClientAndServer-off
// BSLLS:TransferringParametersBetweenClientAndServer-on

Parameter for config

"TransferringParametersBetweenClientAndServer": false