[BUG][Discover] "_source" Not Added to Side Nav on Removing All Columns with doc_table:hideTimeColumn Enabled

[MadaniKK]

Describe the bug

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To Reproduce
Steps to reproduce the behavior:

1. Go to discover: advanced setting
2. set doc_table:hideTimeColum to ON
3. Go to Discover
4. Select a column, then remove it in the canvas

Expected behavior
A clear and concise description of what you expected to happen.
"_source" should be in the selected field when all columns are removed and no other field is selected.
OpenSearch Version
3.0.0

Dashboards Version
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Plugins

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Host/Environment (please complete the following information):

• OS: [e.g. iOS]
• Browser and version [e.g. 22]

Additional context

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[MadaniKK]

May I take this issue? Ty.

[ananzh]

In the legacy Discover, there is no time field. But in new Discover, we could see a time field in the left nav.

But add it or remove it from left nav won't make any differences. The correct behavior should be, and pls help me verify

• No time field in side nav
• When display a time based index pattern, time field is displayed in the table by default
• When doc_table:hideTimeColumn is on, time field is not displayed in the table

[MadaniKK]

1. I suggest keeping the time field in the side nav bar because it exists in the legacy cover, and when the hide time column is off, we can still add the time column to the selected field and use drag-drop to arrange column order.
2. I think for the canvas, the removeColumn probably is off, it doesn't guarantee the column array with a safe fallback. I saw in the code that we added an extra buildColumn(columns) before rendering the canvas, which is why the canvas still behaves correctly when removing columns.

   OpenSearch-Dashboards/src/plugins/discover/public/application/components/data_grid/data_grid_table.tsx

   Lines 59 to 68 in 3268e37

   	let adjustedColumns = buildColumns(columns);
   	// handle case where the user removes selected filed and leaves only time column
   	if (
   	adjustedColumns.length === 1 &&
   	indexPattern &&
   	adjustedColumns[0] === indexPattern.timeFieldName
   	) {
   	adjustedColumns = [...adjustedColumns, '_source'];
   	}

   
   And this problem doesn't show when hideTime is off might be because the time field gets automatically added to columns every time we remove a column from canvas (just as described in issue [BUG][Disocver] Timefield of an indexPattern would get added to selected field in the side nav when removing a column from the canvas #5527 ) I think adding a buildColumn(columns) before rendering the side bar like in the canvas code, would be an easy solution. But in the future, we should check with removeColumn functions and see why it didn't trigger the removing function with the safe fallback.

[ananzh]

Close it as it is resolved in #5537