freedom ui cancel HandleViewModelAttributeChangeRequest

Hi Harvey,

 

We can create an attribute to store a value that you want to set in HandleViewModelInitRequest. Then, in HandleViewModelAttributeChangeRequest, we can check if the current field value matches the one you previously set. If it does not match, we can assign the stored value to it. This way, we ensure that the desired value is assigned to the field.



In the given example, we have created an attribute named "UsrInitialValue".

viewModelConfig: /**SCHEMA_VIEW_MODEL_CONFIG*/{
			"attributes": {
				"StringAttribute_ljc6yh6": {
					"modelConfig": {
						"path": "PDS.UsrTestString"
					}
				},
				"UsrInitialValue": {}
			}
		}/**SCHEMA_VIEW_MODEL_CONFIG*/,

This attribute is used to store a specific value that we set during the initialization process. In the crt.HandleViewModelInitRequest handler, we set a value for the request.$context.UsrInitialValue. And in crt.HandleViewModelAttributeChangeRequest, we check if the current field value matches the value we set previously in the request.$context.UsrInitialValue. If they don't match, we update the field with the new value.

 

handlers: /**SCHEMA_HANDLERS*/[
			{
				request: "crt.HandleViewModelInitRequest",
				handler: async (request, next) => {
					request.$context.UsrInitialValue = "testInit";
					request.$context.StringAttribute_ljc6yh6 = await request.$context.UsrInitialValue;
					return next?.handle(request);
				}
			},
 
			{
				request: "crt.HandleViewModelAttributeChangeRequest",
				handler: async (request, next) => {
					var srtValue = await request.$context.StringAttribute_ljc6yh6;
					var initVal = await request.$context.UsrInitialValue;
					if (request.attributeName === 'StringAttribute_ljc6yh6' && srtValue != initVal) {
						request.$context.StringAttribute_ljc6yh6 = initVal;
					}
					return next?.handle(request);
				}
			}
		]/**SCHEMA_HANDLERS*/,

Artem Smyrnov,

I think this would prevent any modification to the data, including intended changing by the user or system. Obviously it could be changed to add some more conditions, but really the main thing we want/frequently need is for the crt.HandleViewModelInitRequest request to be able to initialise a value and not be overwritten by the standard page loading stuff (loading default values for the entity, clearing out the field where there are no default values etc). I'm pretty sure this was possible in Classic UI, it just doesn't seem to be currently in Freedom UI without some pretty nasty hacks.

Harvey Adcock,

There is no logic that could be used to revert changes to the column value that were done by the handler.

As a solution, you need to create a column that will not use any other handler and set the value using your custom handler. This will prevent the value from being overwritten by other handlers or custom logic.

We have a workaround in place, but this capability has been required a few times - it would be good if Creatio supported setting values on the page in the init handler (or some other handler, maybe a new initvalues handler or something) since per-page default values is often required.