real time code generation incorrect while dragging?

[gengshenghong]

Problem statement

It can reproduce with the online demo at: https://developers.google.com/blockly/
While dragging a block from toolbox, the real time generation of code is incorrect.

Expected Behavior

N/A

Actual Behavior

Steps to Reproduce

1. open 'https://developers.google.com/blockly/'
2. use the "Try Blockly"
3. switch "Language" to "Python" (also fail with other language in fact...).
4. drag "if do" block in "logic"
5. while dragging, the generated code is as below:

if False:
  pass

if False:
 pass

which is incorrect and confusing to user.
6. stop dragging and put the block in workspace, the generated code is as below:

if False:
  pass

which is correct.

Stack Traces

N/A

Operating System and Browser

Mac OSX, Chrome

Additional Information

N/A

[acbart]

I can confirm this is happening on my machine too (Windows 10, Chrome). While you are dragging, the result of getTopBlocks() has the extra dragged block.

[RoboErikG]

This is most likely caused by insertion markers and a missing a check somewhere to skip them.

[gengshenghong]

Yes, it is caused by insertion markers, and can be fixed as below:

Blockly.Generator.prototype.workspaceToCode = function(workspace) {
  .....
  var blocks = workspace.getTopBlocks(true);
  for (var x = 0, block; block = blocks[x]; x++) {
      if(block.isInsertionMarker_) { // FIX: add this to ignore insertion markers!!!
        continue;
      }

However, it only fixed the issue when dragging a new block from toolbox. It still has issues in other cases: when two block are connected, drag it out, it will also generate wrong code, which is not fixed by above code. Is it a different root cause? Any idea.

By the way, I've tested BlockPy @acbart (nice project), and it works well (split mode). It seems like you are using an old version of Blockly?

[acbart]

Thanks - and yes, we're upgrading to the latest version this summer. Hence all my Issues and Pull Requests :)

[gengshenghong]

I've fixed it with PR. There are two places required to check whether it is insertion marker to avoid incorrect code generation to cover the two cases I mentioned.

Thanks,
Shenghong

[rachel-fenichel]

See #2322 for more discussion of problems related to insertion markers. A better solution is to not generate code while dragging, which you can check with workspace.isDragging().