How to Fix Your Live Power BI Model Straight from the Browser

The Revenue measure on a published sales model is supposed to return net revenue, after discounts. It sums Sales[Total Amount] instead, which is gross revenue, and the business wants it fixed now. TMDL view on the web lets you make that fix in the Power BI service, on the published model, without opening Power BI Desktop or republishing. This article fixes the measure, then uses the same model to add security roles, rename a column across the model, and recover from a rename that broke the report.

0:11The republish tax

The usual way to change a published model is to open the .pbix in Desktop, make the change, publish it again, and refresh the semantic model in the service. A one-word fix still pays for all of that:

• The refresh after a republish can take a while, and until it finishes, people see old data.
• You can skip the republish by editing the published model through the XMLA endpoint, with a tool like Tabular Editor. But Microsoft Learn warns that a write operation on a model authored in Desktop prevents downloading it back as a .pbix. If the way you back up your Power BI files depends on that download, it matters.
• A measure that’s wrong right now can’t always wait for the next refresh window.

A model with incremental refresh has the download limit from the start: the service won’t give you a copy of it with its data, only a report with a live connection to the model.

TMDL view on the web is the TMDL code editor inside the Power BI service, working directly on the published model. TMDL view has been in Power BI Desktop since January 2025, and it has been available in the service, in preview, since July 2026.

1:04TMDL view in the Power BI service

Open the semantic model in the service: in the workspace, select More options (…) next to the model, then Open semantic model. It opens in Model view, and the buttons at the bottom left switch between Model view, DAX query view and TMDL View (Preview).

TMDL view is a large text editor for TMDL scripts. The Data pane on the right lists the model’s tables on its Tables tab, and everything else, such as relationships and measures, on its Model tab.

TMDL view on a published model, in Viewing mode. The view switcher is at the bottom left.

To use it, you need:

• Write permission on the semantic model.
• Semantic model editing in the service turned on for you. A Power BI administrator controls it in the admin portal, for the whole organization or for specific security groups.
• A model the service can open for editing. Models with a live connection, models with automatic aggregations, and models not yet upgraded to the enhanced metadata format can’t be opened.

The model opens in Viewing mode. You can script objects and preview changes, but Apply stays greyed out until you switch to Editing with the mode toggle at the top right. TMDL view in Desktop has no modes: you can apply a change at any time.

To script an object, drag it from the Data pane into the editor, or right-click it and select Script TMDL to, then Script tab or Clipboard. You can also drag a whole section, such as all the measures, or the whole model. Either way you get a createOrReplace script of everything the object defines.

1:54The hotfix: script it, diff it, apply it

The hotfix loop: script and preview in Viewing mode, apply in Editing mode, with version history as the way back.

In the Data pane’s Model tab, search for “revenue”. The measure is called Revenue. Right-click it and script it to a tab:

createOrReplace

	ref table Sales

		/// Net sales revenue after discounts. Primary measure of the report.
		measure Revenue = SUM(Sales[Total Amount])
			formatString: $#,##0
			lineageTag: c1c52f36-46b8-4d95-944b-14c50e42cb3a

ref table Sales refers to the existing table without redefining it, so applying this script replaces the Revenue measure and leaves the rest of the table alone. Without ref, table Sales would be the table’s full definition, and createOrReplace would replace the whole table with only what the script holds. Microsoft Learn’s page on TMDL scripts shows both forms. The measure comes with everything it defines: its description (the /// line), its format string and its lineage tag.

The expression is the problem. The description says net sales revenue after discounts, but Sales[Total Amount] is the amount before discounts, so the measure returns gross revenue. The model already has a Gross Sales measure for that. The fix is one word, Total Amount to Net Amount:

		measure Revenue = SUM(Sales[Net Amount])

Select Preview. A side-by-side diff opens, with the model before the script on the left and after it on the right. Red marks removed or changed lines, and green marks new ones. Here the only change is the measure’s expression.

Preview compares the model before and after the script. The one change is Total Amount to Net Amount.

The preview compares the whole model before and after the script runs, not your script’s text. Microsoft Learn points out what that means: properties can appear in TMDL’s default order rather than the order you typed them in.

When the diff looks right, close the preview, switch from Viewing to Editing at the top right, and select Apply. Its tooltip reads: “Apply your changes to the model. This can’t be undone.” A moment later, a banner reads “Changes applied to the model.”

Back on the report, the revenue card still shows $3.1 million. Refresh the page, and it shows $2.9 million.

3:31Apply is metadata only

Apply changes the model’s metadata, its definitions. It doesn’t refresh any data. For a measure, that’s all you need: a measure is calculated when a visual asks for it, so the fix shows up the next time the report queries it. That’s why the card changed on a page refresh.

A calculated column or a Power Query step takes one more step. Change a calculated column’s DAX or a table’s Power Query, and the new code is in the model as soon as you apply it, but the column’s values and the table’s data are only updated when that table is refreshed. After a change like that, refresh the table, or the whole model, before you check the result.

What apply changes at once, and what waits for a refresh.

4:11Write RLS roles in TMDL

The business also wants row-level security. The company has stores in six states and wants a role for each one. The model has no roles yet: its security page in the service lists none, and the Data pane counts zero.

One script creates all six:

createOrReplace

	role 'FL Sales'
		modelPermission: read

		tablePermission Store = Store[State] = "FL"

	role 'IL Sales'
		modelPermission: read

		tablePermission Store = Store[State] = "IL"

	role 'MA Sales'
		modelPermission: read

		tablePermission Store = Store[State] = "MA"

	role 'NY Sales'
		modelPermission: read

		tablePermission Store = Store[State] = "NY"

	role 'TX Sales'
		modelPermission: read

		tablePermission Store = Store[State] = "TX"

	role 'WA Sales'
		modelPermission: read

		tablePermission Store = Store[State] = "WA"

Each role can read the model (modelPermission: read) and has a table permission on Store that keeps only the rows where the State column equals its state. Paste the script into a tab and apply it in Editing mode.

One script creates the six roles. Apply’s tooltip warns that the change can’t be undone.

Refresh the model’s security page, and it lists all six roles. The script creates the roles without putting anyone in them. To assign users and groups, open the semantic model in the service, select Manage roles in the ribbon, and use the Assign tab.

5:11Bulk rename with find and replace

Say you’d rather call the Net Amount column Net Revenue. To rename an object in TMDL view, you script its parent: the table for a column, the whole model for a table. Open a clean script tab and drag the entire semantic model into it. This one comes to about 1,500 lines of TMDL.

Press Ctrl+F (Cmd+F on a Mac, where TMDL view on the web works too), search for net amount, and expand the box to show the replace field. Enter Net Revenue. There are four matches, and only two of them should change:

1. The reference in the Revenue measure, SUM(Sales[Net Amount]): replace it.
2. The column definition, column 'Net Amount': replace it.
3. sourceColumn: Net Amount: skip it.
4. {"Net Amount", type number} in the Power Query step of the Sales partition: skip it.

sourceColumn is the name of the column as it comes out of Power Query, and the model’s column is bound to it. Rename it, and the model looks for a Net Revenue column that Power Query doesn’t produce, unless you also add a rename step to the query. Microsoft Learn describes the two names as independent: the model’s column can be called Net Revenue while Power Query, and its editor, still call it Net Amount. The fourth match is that Power Query name itself, in the step that sets the column types.

That’s why Replace All is the wrong button here: it would change all four. Replace the first two one at a time, and move past the other two with the next-match arrow.

The two matches left stay as they are: sourceColumn and the Power Query step both use the name Power Query produces.

After the two replacements, the measure reads SUM(Sales[Net Revenue]), and the column reads:

	column 'Net Revenue'
		dataType: double
		isHidden
		lineageTag: b0401191-b079-4de3-9f30-88ecaa718708
		summarizeBy: none
		sourceColumn: Net Amount

Apply it, and the column is renamed in the model and in the measure that uses it, while Power Query keeps producing Net Amount, and everything still works.

The same box takes regular expressions, for renames by pattern. Microsoft Learn’s example lowercases every column name in a scripted table: turn on the regular expression option (the .* button at the right end of the find field), enter these patterns, and select Replace All.

Find	Replace
(^\s+column\s+)(.+)	$1\L$2

Here Replace All is the right button: the pattern matches only lines that start with column, so the sourceColumn lines keep the names Power Query produces.

6:55When a rename breaks report visuals

One more edit: rename the Revenue measure to Total Net Revenue. Typed as is, the new name gets an error in the editor, because a name with spaces needs single quotes:

		measure 'Total Net Revenue' = SUM(Sales[Net Revenue])

Apply it, go to the report, and refresh the browser. Many of the visuals now show “Something’s wrong with one or more fields.”

The report after the measure rename: the visuals bound to the old name show errors.

The rename is code only. When you rename a field in Power BI Desktop’s interface, the change carries through the model and into the report’s visuals. A rename in a script doesn’t carry through: the visuals still ask for Revenue, which no longer exists. Microsoft Learn warns about this in both places: renaming a field in TMDL view may break visuals that use it, and when you edit a model in the service, renamed fields don’t update in existing visuals in the reports built on it.

So before you rename a field that reports use, find those reports, or keep the old name. If a rename has already broken a report, rename the field back, or restore the version from before the change.

7:41Roll back with version history

In TMDL view, switch to Editing mode, then select File, then Version history. The same pane opens from the workspace (More options (…) next to the model) and from the model’s details page (File).

Version history for the model. Each saved version’s menu (…) has Restore.

Each version shows when it was last changed and who changed it. To roll back, open the menu (…) on the version you want and select Restore.

Versions aren’t necessarily saved at the moments you’d pick. Microsoft Learn lists when one is saved:

• When you open the model on the web in Editing mode.
• When someone publishes a .pbix over the model from Desktop, or uploads one on the web. The version saved is the one from before the publish.
• When you restore a version. The version saved is the one from before the restore.
• When you select File, then Save to version history, in Editing mode. You can add a description, which appears with the version in the pane.

So before a change you might want to undo, save a version yourself, with a description that says what’s about to change.

The limits, also from Learn:

• Up to five versions per model. Saving another once there are five overwrites the oldest.
• Restoring a version older than 14 days isn’t supported.
• Each version holds the model’s metadata and data, so the data can be out of date after a restore. Refresh the model afterward.
• You need Write and Build permission on the model, and version history isn’t available with a free license.

Learn’s comparison of the two TMDL views lists this version history as not available in Desktop. A .pbix saved to OneDrive or SharePoint keeps file versions instead, which Easy Version History Comes to Power BI Desktop covers.

8:18Script tabs are ephemeral

The script tabs at the bottom of TMDL view on the web don’t last. Close the browser tab, or the model, and they’re gone, as the banner at the top of the editor warns: “TMDL scripts are discarded on close.” They aren’t written to the workspace, and they aren’t written to a Git repository either, even when the workspace is synced to one. Scripts saved in the model from Desktop don’t show up on the web.

Desktop keeps its script tabs, in the .pbix, or as .tmdl files in the TMDLScripts folder of a Power BI project. Learn adds one caveat for Git: setting up a workspace’s Git integration for the first time doesn’t include TMDL view scripts saved in a published model.

I like that the web scripts go away, because saved scripts tend to clutter my code repository. If you want to keep one, such as the role script or a fix you’ll use again, save it to a file before you close the tab.

9:04Where Power BI development is heading

I don’t think Power BI Desktop is going anywhere soon. But TMDL view on the web closes a gap in web-first development for Power BI: it gives you nearly everything you need to develop in the browser, and to work much more code forward. Here’s how the two TMDL views compare:

	TMDL view in Power BI Desktop	TMDL view on the web
Status	Generally available	Preview
Modes	None: apply a change at any time	Viewing mode to script and preview, Editing mode to apply
Script tabs	Saved in the .pbix, or as .tmdl files in a project	Discarded when the model or the browser closes
Version history	Not in TMDL view; a .pbix saved to OneDrive or SharePoint keeps file versions	Up to five versions of the model
Permissions	No workspace permission involved	Write permission on the semantic model
Where it runs	Power BI Desktop on Windows	A browser, including on a Mac

If you’re serious about building in Power BI, get familiar with TMDL. Reading your model as TMDL speeds up the work you already do, and it shows you how to do things you might not have known how to do before. You can do that in Desktop’s TMDL view, and now you can do it in a browser too.

10:02Try a browser hotfix this week

Pick an edit you’ve been meaning to make. Open the model in the service, open TMDL view, save a version, and make the change. Version history is your friend, so save versions often.

To treat your reports as code too, Power BI as Code: The Setup AI Needs for Your Reports follows one report saved as a Power BI project, where every page, visual and measure becomes a text file.