ui-dropdown doesn't clear selection with msg.payload = []

[18802496555]

Current Behavior

after selected an option, by sending msg.payload=[] will not clear seletion as documented

Expected Behavior

by send msg.payload =[] to ui-dropdown node will clear selection

Steps To Reproduce

[{"id":"b878241ae48df373","type":"inject","z":"b481f6a7426a1928","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":630,"y":1060,"wires":[["fc2672e929484423"]]},{"id":"fc2672e929484423","type":"function","z":"b481f6a7426a1928","name":"function 21","func":"msg.payload = [];\n\nreturn msg;","outputs":1,"timeout":0,"noerr":0,"initialize":"","finalize":"","libs":[],"x":810,"y":1060,"wires":[["f45a08fdd76cf08f"]]},{"id":"f45a08fdd76cf08f","type":"ui-dropdown","z":"b481f6a7426a1928","group":"e039e314bc87dbdd","name":"test","label":"test","tooltip":"","order":0,"width":"3","height":"1","passthru":true,"multiple":false,"options":[{"label":"a","value":"1","type":"str"},{"label":"b","value":"2","type":"str"},{"label":"c","value":"3","type":"str"}],"payload":"","topic":"topic","topicType":"msg","className":"","x":990,"y":1060,"wires":[["5ad6a6f2fc2c422e"]]},{"id":"5ad6a6f2fc2c422e","type":"debug","z":"b481f6a7426a1928","name":"debug 208","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":1140,"y":1060,"wires":[]},{"id":"e039e314bc87dbdd","type":"ui-group","name":"按键选择","page":"ce60fd917fc93e18","width":"12","height":"1","order":-1,"showTitle":true,"className":"","visible":"true","disabled":"false"},{"id":"ce60fd917fc93e18","type":"ui-page","name":"场景管理","ui":"bbbca6a8a7b43502","path":"/page4","icon":"home","layout":"grid","theme":"a320a731ce51b7c0","order":4,"className":"","visible":"true","disabled":"false"},{"id":"bbbca6a8a7b43502","type":"ui-base","name":"管理面板","path":"/dashboard","includeClientData":true,"acceptsClientConfig":["ui-notification","ui-control"],"showPathInSidebar":false,"navigationStyle":"fixed"},{"id":"a320a731ce51b7c0","type":"ui-theme","name":"Default Theme","colors":{"surface":"#24292e","primary":"#097479","bgPage":"#111111","groupBg":"#333333","groupOutline":"#cccccc"},"sizes":{"pagePadding":"12px","groupGap":"12px","groupBorderRadius":"4px","widgetGap":"12px"}}]

Environment

• Dashboard version: 2.0
• Node-RED version: 3.18
• Node.js version:
• npm version:
• Platform/OS: hassio
• Browser: edge

Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate

[colinl]

I can confirm that sending an empty array does not clear it, and neither does an empty string. However, if the node is changed to multi-select then an empty array does clear it.

[18802496555]

is this a bug or it is designed to work only with multi-selection?

[colinl]

There is a bug, there should be a way of clearing single selection dropdowns. Whether, for single selection, it should be an empty string (which seems logical to me) or should still be an empty array I will leave to the developers. Perhaps both options should work in both cases.

[bartbutenaers]

@colinl,
Last week I had created a pull request for dynamic control of radiobuttons, which can be cleared using an empty string. I will have a look to create a PR to do the same for drpodowns tonight.
Bart

[colinl]

The docs currently say it should be an empty array. Whether it should also allow an empty string I don't know.

[bartbutenaers]

Yes indeed. An empty array seems to make more sense to me compared to an empty string, because the dropdown can contain different kind of data types (i.e. not only strings):

[bartbutenaers]

Pull request created.

[joepavitt]

Closed by #775