connect-pbid

name

connect-pbid

description

TOM and ADOMD.NET guidance via PowerShell for connecting to Power BI Desktop's local Analysis Services instance. Covers model enumeration, DAX queries, metadata modification, annotations, calendar definitions, field parameters, query tracing, DAX library package management (daxlib.org), and the Desktop Bridge for reloading and screenshotting the report canvas. Automatically invoke when the user mentions "Power BI Desktop", "Analysis Services port", "TOM", "ADOMD", "daxlib", "DAX library", "DAX UDF package", or asks to "connect to PBI Desktop", "query PBI Desktop with DAX", "modify PBI Desktop model", "add a measure to PBI", "capture visual queries", "create a field parameter", "validate DAX", "intercept DAX queries", "install daxlib", "add DAX SVG", "add IBCS", "reload the report canvas", "screenshot a report page", "Desktop Bridge", or to work with the model and report in Power BI Desktop together.

Connect to Power BI Desktop (Local Analysis Services)

CRITICAL: Record mistakes, surprises, and model-specific nuances encountered while using this skill in .claude/rules/connect-pbid.md. This file must begin with "Learnings from Claude about connecting to semantic models via the connect-pbid skill". Write only active reference notes (e.g. "QueryGroup property returns an object; access .Folder for the name string"); do not log a changelog or history of events. Omit anything already documented in the skill or its references. Keep the file under 1500 characters at all times; prune stale entries when adding new ones. Do not over-attend to this file; update it only when something genuinely unexpected is discovered.

Note: No MCP server is required. Use PowerShell with TOM/ADOMD.NET for the local model. When the report canvas is also in scope, pair it with pbir for report operations; never patch report JSON directly.

Expert guidance for connecting to Power BI Desktop's local tabular model via the Tabular Object Model (TOM) and ADOMD.NET in PowerShell. Covers connection, enumeration, DAX queries, query traces, and full model modification.

When to Use This Skill

Activate only when the Tabular Editor CLI or a Power BI MCP server is unavailable. TOM is more reliable than direct TMDL editing because it validates changes against the engine and applies them atomically.

WARNING: This skill does NOT support remote models via the XMLA endpoint. For Direct Lake models or models hosted in Fabric, use the Tabular Editor CLI or a Power BI MCP server instead; the local Analysis Services proxy does not expose Direct Lake databases to external TOM/ADOMD.NET connections.

Model and report: routing

Power BI Desktop exposes the model and the report as two separate local surfaces. This skill owns the model surface and report-canvas verification, and routes report authoring to the right skill:

• Model (tables, columns, measures, relationships, roles, calculation groups, refresh): this skill, via TOM/ADOMD over the local Analysis Services instance. For model edits, prefer the te CLI or a model MCP when available; fall back to this skill's TOM when they are not (see "When to Use This Skill").
• Report-canvas verification (reload after edits, screenshot pages): this skill, the raw Desktop Bridge named-pipe API (section 13).
• Report authoring (visuals, pages, formatting, filters, bookmarks, themes): the pbir-cli skill in the reports plugin (it drives the pbir CLI). The Desktop Bridge here only reloads and screenshots; it never edits visuals. Route every visual or page change to pbir-cli.
• Report JSON edited directly (only when pbir is unavailable): the pbir-format skill in the pbip plugin.

Full loop on an open PBIP: change the model with TOM here, change visuals with pbir-cli, then reload and screenshot with the Desktop Bridge here to verify, and iterate.

Critical

• Power BI Desktop must be open with a model loaded before connecting; if there are errors it is likely due to a "thin report" connected to a remote model, or a Direct Lake model (which uses a remote proxy that blocks external connections)
• The local Analysis Services instance only accepts connections from localhost
• Multiple PBI Desktop files open means multiple msmdsrv.exe processes on different ports. Connect to each port, read $server.Databases[0].Name, and ask the user which model to work with if more than one is found. When the pbir CLI is installed, prefer pbir desktop list to map each Desktop PID to the exact file it has open (see Section 2a)
• A workspace engine reporting Databases: 0 belongs to a thin report (live connection to a remote model); there is no local model to connect to. Query thin reports through their remote model instead (pbir model -q routes there automatically)
• Always use a timeout of 60000ms or higher for PowerShell commands via Bash
• Shell escaping: Bash eats PowerShell $ variables ($env:TEMP, $server, etc.) silently. Two options: (1) single-quote the -Command arg so Bash passes $ literally to PowerShell; (2) write a .ps1 file with a heredoc (single-quoted delimiter preserves $) and use -File. On macOS via Parallels, the prlctl -> cmd.exe -> powershell.exe chain adds extra escaping layers; .ps1 files are more reliable for complex scripts but inline -Command with single quotes works for short commands.
• Always use -ExecutionPolicy Bypass when running PowerShell commands or scripts. Windows blocks unsigned scripts by default.
• Script file location -- persistent scripts should go in the agent harness's scripts directory for the project (.claude/scripts/, .github/scripts/, .cursor/scripts/, .gemini/scripts/, etc. depending on the harness). Ephemeral or throwaway scripts should go in a project tmp/ directory (which should be .gitignored). Do not write scripts to ./ root or /tmp/.
• Do not modify model metadata without explicit user direction
• Always call $model.SaveChanges() to persist modifications; without it, changes are discarded
• For macOS users running PBI Desktop in Parallels, see parallels-macos.md
• Validation hooks are active for this plugin; they validate DAX references, enforce measure metadata, check referential integrity, and report compatibility level upgrade opportunities. Toggle checks in hooks/config.yaml.

1. Prerequisites

Requirement	Description
Power BI Desktop	Open with a model loaded (.pbix or .pbip)
PowerShell	Available on the machine running PBI Desktop
NuGet CLI	For package installation (winget install Microsoft.NuGet)
TOM NuGet Package	Microsoft.AnalysisServices.retail.amd64 -- model metadata
ADOMD.NET Package	Microsoft.AnalysisServices.AdomdClient.retail.amd64 -- DAX queries

Install both packages only if not already present:

$pkgDir = "$env:TEMP\tom_nuget"
if (-not (Test-Path "$pkgDir\Microsoft.AnalysisServices.retail.amd64")) {
    nuget install Microsoft.AnalysisServices.retail.amd64 -OutputDirectory $pkgDir -ExcludeVersion
}
if (-not (Test-Path "$pkgDir\Microsoft.AnalysisServices.AdomdClient.retail.amd64")) {
    nuget install Microsoft.AnalysisServices.AdomdClient.retail.amd64 -OutputDirectory $pkgDir -ExcludeVersion
}

Packages install DLLs under lib\net45\. Load with Add-Type -Path.

If a TOM operation fails with a compatibility level error or missing type, the .retail.amd64 package may be too old. A newer package (Microsoft.AnalysisServices, .NET 8+) ships with more recent TOM features. See daxlib.md for details on package differences.

2. Quickstart

Find the port, load TOM, connect, enumerate -- in one script:

# Find ports (deduped; netstat lists IPv4 and IPv6 entries per port)
$pids = (Get-Process msmdsrv -ErrorAction SilentlyContinue).Id
$ports = netstat -ano | Select-String "LISTENING" |
    Where-Object { $pids -contains ($_ -split "\s+")[-1] } |
    ForEach-Object { ($_ -split "\s+")[2] -replace ".*:" } |
    Select-Object -Unique

# Load TOM
$basePath = "$env:TEMP\tom_nuget\Microsoft.AnalysisServices.retail.amd64\lib\net45"
Add-Type -Path "$basePath\Microsoft.AnalysisServices.Core.dll"
Add-Type -Path "$basePath\Microsoft.AnalysisServices.Tabular.dll"

# Connect to the first port that hosts a model; skip thin-report engines (0 databases)
$server = New-Object Microsoft.AnalysisServices.Tabular.Server
foreach ($p in $ports) {
    $server.Connect("Data Source=localhost:$p")
    if ($server.Databases.Count -eq 0) {
        Write-Output "localhost:$p hosts no model (thin report); trying next port"
        $server.Disconnect()
        continue
    }
    break
}
$model = $server.Databases[0].Model

# Enumerate
foreach ($table in $model.Tables) {
    Write-Output "TABLE: [$($table.Name)] ($($table.Columns.Count) cols, $($table.Measures.Count) measures)"
}
Write-Output "Relationships: $($model.Relationships.Count)"

$server.Disconnect()

Port discovery methods:

Method	Install Type	Command
Port file	Non-Store PBI Desktop	Get-Content "$env:LOCALAPPDATA\Microsoft\Power BI Desktop\AnalysisServicesWorkspaces\*\Data\msmdsrv.port.txt"
Port file	Store PBI Desktop	Get-Content "$env:LOCALAPPDATA\Packages\Microsoft.MicrosoftPowerBIDesktop_*\LocalState\AnalysisServicesWorkspaces\*\Data\msmdsrv.port.txt"
netstat	Any	netstat -ano | findstr LISTENING | findstr <PID>

2a. Correlating Ports to Reports (Multiple Instances)

A port alone does not identify the report it serves; correlate before connecting to avoid modifying the wrong model. With the pbir CLI and Desktop's "external tool access" preview feature enabled, pbir desktop list shows each Desktop PID with the exact file it has open. Map ports to those PIDs through the process tree (each msmdsrv.exe is a child of its PBIDesktop.exe):

$conns = Get-NetTCPConnection -State Listen
foreach ($proc in Get-Process msmdsrv -ErrorAction SilentlyContinue) {
    $port = ($conns | Where-Object OwningProcess -eq $proc.Id | Select-Object -First 1).LocalPort
    $parent = (Get-WmiObject Win32_Process -Filter "ProcessId=$($proc.Id)").ParentProcessId
    Write-Output "port $port -> msmdsrv $($proc.Id) -> PBIDesktop $parent"
}

An engine reporting Databases: 0 is a thin report's workspace; no local model exists. Query the remote model instead (pbir model -q routes there automatically).

3. Loading TOM, Connecting, and Saving Changes

Load Assemblies

$basePath = "$env:TEMP\tom_nuget\Microsoft.AnalysisServices.retail.amd64\lib\net45"
Add-Type -Path "$basePath\Microsoft.AnalysisServices.Core.dll"
Add-Type -Path "$basePath\Microsoft.AnalysisServices.Tabular.dll"
Add-Type -Path "$basePath\Microsoft.AnalysisServices.Tabular.Json.dll"

Connect

$server = New-Object Microsoft.AnalysisServices.Tabular.Server
$server.Connect("Data Source=localhost:<PORT>")

# PBI Desktop always has exactly one database
$db = $server.Databases[0]
$model = $db.Model

Save Changes

Only save after all changes are made. After modifications, persist with:

$model.SaveChanges()

Changes appear immediately in PBI Desktop. The user cannot undo with Ctrl+Z in Power BI, which is a disadvantage of this approach.

Disconnect

IMPORTANT: Remember to disconnect after modifications are done. NEVER remain connected, which can lead to orphaned processes.

$server.Disconnect()

Connection Properties

Write-Output "Server: $($server.Name)"
Write-Output "Version: $($server.Version)"
Write-Output "Database: $($db.Name)"
Write-Output "Compatibility: $($db.CompatibilityLevel)"

4. Refreshing the Model

Trigger a data refresh via TMSL (Tabular Model Scripting Language) or TOM's RequestRefresh API. This re-executes Power Query/M expressions and reloads data into the VertiPaq engine.

# Full refresh of a single table via TMSL
$dbName = $server.Databases[0].Name
$tmsl = '{ "refresh": { "type": "full", "objects": [{ "database": "' + $dbName + '", "table": "Sales" }] } }'
$server.Execute($tmsl)

# Or via TOM RequestRefresh API
$model.Tables["Sales"].RequestRefresh([Microsoft.AnalysisServices.Tabular.RefreshType]::Full)
$model.SaveChanges()

Refresh Type	Behaviour
full	Drop data, re-query source, recalculate DAX
calculate	Recalculate DAX only (no source query)
automatic	Engine decides per-partition what's needed
dataOnly	Re-query source but skip DAX recalculation

For detailed examples and all refresh methods, see refresh-model.md.

5. Querying with DAX

Load ADOMD.NET

Add-Type -Path "$env:TEMP\tom_nuget\Microsoft.AnalysisServices.AdomdClient.retail.amd64\lib\net45\Microsoft.AnalysisServices.AdomdClient.dll"

Open a Connection

$conn = New-Object Microsoft.AnalysisServices.AdomdClient.AdomdConnection
$conn.ConnectionString = "Data Source=localhost:<PORT>"
$conn.Open()

Execute a Query

All queries should preferably use SUMMARIZECOLUMNS. Check dax.guide online for information about DAX functions, if necessary.

Important: ADOMD.NET returns fully-qualified column names without quotes around the table name (e.g., Brands[Brand Class] not Brand Class; measure projections come back as [@Alias]). Do not access columns by short name ($reader["Brand Class"]) -- it fails silently and returns blank. Use $reader.GetName($i) to discover column names, then access by index:

$cmd = $conn.CreateCommand()
$cmd.CommandText = "EVALUATE SUMMARIZECOLUMNS('Table'[Column], ""@MeasureName"", [Measure])"

$reader = $cmd.ExecuteReader()

# Always iterate by index and use GetName() to map columns
while ($reader.Read()) {
    for ($i = 0; $i -lt $reader.FieldCount; $i++) {
        Write-Output "$($reader.GetName($i)): $($reader.GetValue($i))"
    }
    Write-Output "---"
}
$reader.Close()

DAX Rules

• Always fully qualify column references with single-quoted table names: 'Sales'[Amount], not [Amount]. This applies everywhere -- measures, calculated columns, queries. Unqualified columns cause ambiguity errors.
• Table names are always single-quoted in DAX: 'Sales'[Amount], 'D&D 5E Monsters'[CR]. Even simple names like Sales should be quoted as 'Sales' for consistency.
• Measure references are the only exception -- they are always unqualified: [Total Revenue]
• String literals in DAX use double quotes, escaped as "" inside PowerShell here-strings

Query Patterns

# Full table scan
$cmd.CommandText = "EVALUATE 'Sales'"

# Filtered with CALCULATETABLE
$cmd.CommandText = "EVALUATE CALCULATETABLE('Sales', 'Sales'[Region] = ""West"")"

# Aggregation
$cmd.CommandText = "EVALUATE SUMMARIZECOLUMNS('Date'[Year], ""@Total"", SUM('Sales'[Amount]))"

# Scalar via ROW
$cmd.CommandText = "EVALUATE ROW(""Result"", COUNTROWS('Sales'))"

# DMV queries (model metadata via SQL-like syntax)
$cmd.CommandText = "SELECT * FROM `$SYSTEM.TMSCHEMA_TABLES"