bug(mat-table): Table not refreshing on nested detail-row column change

[angelaki]

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

I'm not sure if this scenario is supported by the API at all but imho it should be a valid scenario.

If I have an array of detail rows changing their columns does not automatically redraw the table. If I know all the rows in advance (do not use @for) it works as expected.

Reproduction

StackBlitz link: https://stackblitz.com/edit/av2ud5lm

Steps to reproduce:

1. Clicking Toggle Secondary changes the json-output but not the table
2. Only on clicking Toggle Primary the table gets redrawn, respecting the current definition for the detail rows

Working StackBlitz link: https://stackblitz.com/edit/av2ud5lm-ardwk8i8
Just to make sure this also happens if all the rows are in a single array (https://stackblitz.com/edit/av2ud5lm-yhdxrfqp)

Not this being a Q/A but just out of curiosity, why do I need multiTemplateDataRows at all? Why won't all (matching) rows get displayed by default? Asking since I tend to always use / set it but guess there might be some kind of disadvantage since this is not the default behavior?

Expected Behavior

Even generic detail rows (created by @for) should behave correct.

Actual Behavior

Right now, I need to know all my detail rows in advance. Since I'm implementing a pretty customizable table, I want to let the user create / define the rows in runtime.

If you're not going to support this case officially, a neat workaround to trigger redrawing the table would be welcome.

Environment

Angular CLI: 19.1.9
Node: 22.11.0
Package Manager: pnpm 10.6.2
OS: win32 x64

Angular: 19.1.8
... animations, common, compiler, compiler-cli, core, forms
... platform-browser, platform-browser-dynamic, router
... service-worker

Package Version

@angular-devkit/architect 0.1901.9 (cli-only)
@angular-devkit/build-angular 19.1.9
@angular-devkit/core 19.1.9 (cli-only)
@angular-devkit/schematics 19.1.9 (cli-only)
@angular/cdk 19.1.5
@angular/cli 19.1.9
@angular/material 19.1.5
@angular/material-luxon-adapter 19.1.5
@schematics/angular 19.1.9 (cli-only)
rxjs 7.8.2
typescript 5.7.3
zone.js 0.15.0

[angelaki]

Right now I'm doing this in an effect watching the displayed rows:

const ds = table.dataSource;
table.dataSource = [];
table.dataSource = ds;
table.renderRows();

renderRows alone won't do the job, setting it to a new array and back probably switched some internal flag. But ...

[angelaki]

Just found the private method _forceRenderDataRows() that I'm calling now:

if (typeof table['_forceRenderDataRows'] === 'function') { (<any>table)._forceRenderDataRows(); }
else if (isDevMode()) { throw new Error('`_forceRenderDataRows` missing in CdkTable'); }

By the way: this method is called when multiTemplateDataRows is set - whether it changed or not. Maybe check this in the setter?