[beam] branch master updated: [BEAM-7923] Fix datatable on notebook reloading

[al...@apache.org]

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altay pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/beam.git


The following commit(s) were added to refs/heads/master by this push:
     new 0f9b59e  [BEAM-7923] Fix datatable on notebook reloading
     new 122d60f  Merge pull request #11262 from KevinGG/BEAM-7923
0f9b59e is described below

commit 0f9b59e14678e525c46f68491c4d04715616ee6b
Author: KevinGG <ka...@gmail.com>
AuthorDate: Mon Mar 30 11:27:24 2020 -0700

    [BEAM-7923] Fix datatable on notebook reloading
    
    1. The problem: when a user reloads the browser window of a jupyter
       notebook page, the javascripts of all output areas are executed
       in an arbitrary order. A datatable's state is gone on the reloading,
       thus causing all the javascripts to reinitialize a datatable.
       When the Javascripts race with each other, a datatable can be
       reinitialized multiple times indeterminably, resulting in multiple
       duplicated datatable wrappers being added to the DOM. The datatable
       is then rendered with multiple search and pagination web elements.
    2. The solution is to disable the javascripts from being executed on
       reloading. There is no use of restoring a datatable's state because
       the whole window is gone on reloading, thus nothing depends on the
       datatable any more. And from the perspective of visualization, the
       DOM with datatable web elements already presents, so no need for
       datatable javascripts either.
    3. Changed the dataframe visualization javascripts to check if a
       datatable wrapper exists before invoking an initialization. If there
       is no datatable object but there is a wrapper, it means this is a
       browser reloading and do nothing.
---
 .../apache_beam/runners/interactive/display/pcoll_visualization.py    | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sdks/python/apache_beam/runners/interactive/display/pcoll_visualization.py b/sdks/python/apache_beam/runners/interactive/display/pcoll_visualization.py
index 873873c..d44a9f3 100644
--- a/sdks/python/apache_beam/runners/interactive/display/pcoll_visualization.py
+++ b/sdks/python/apache_beam/runners/interactive/display/pcoll_visualization.py
@@ -117,10 +117,12 @@ _DATAFRAME_SCRIPT_TEMPLATE = """
             var dt;
             if ($.fn.dataTable.isDataTable("#{table_id}")) {{
               dt = $("#{table_id}").dataTable();
-            }} else {{
+            }} else if ($("#{table_id}_wrapper").length == 0) {{
               dt = $("#{table_id}").dataTable({{
                 """ + _DATATABLE_INITIALIZATION_CONFIG + """
               }});
+            }} else {{
+              return;
             }}
             dt.api()
               .clear()