Dynamic RLS with USERNAME in Power BI - Cell-by-Cell Formula Trace

Sample Data

This table maps each user email to their allowed sales region for dynamic row-level security.

Cell	Value
A1	UserName
B1	Region
A2	[e-mail]
B2	North
A3	[e-mail]
B3	South
A4	[e-mail]
B4	East
A5	[e-mail]
B5	West

Formula Trace

FILTER('Sales', 'Sales'[Region] = LOOKUPVALUE('UserRegion'[Region], 'UserRegion'[UserName], USERNAME()))

Step 1: USERNAME()

Step 2: LOOKUPVALUE('UserRegion'[Region], 'UserRegion'[UserName], "[e-mail]")

Step 3: FILTER('Sales', 'Sales'[Region] = "South")

Cell Reference Map

    A              B
1 | UserName      Region
2 | alice@...     North
3 | bob@...       South
4 | carol@...     East
5 | dave@...      West

References:
- USERNAME() returns current user email
- LOOKUPVALUE uses A2:A5 and B2:B5 to find region
- FILTER applies region filter on Sales data

The USERNAME function uses the UserName column (A2:A5) to find the matching Region in column B2:B5 for filtering.

Result

Sales Table (Filtered for [e-mail]):

| OrderID | Region | SalesAmount |
|---------|--------|-------------|
| 102     | South  | 5000        |
| 108     | South  | 3200        |

Only rows with Region 'South' are visible to [e-mail].

The final filtered sales table shows only rows where Region equals 'South', matching the logged-in user's allowed region.

Sheet Trace Quiz - 3 Questions

What does USERNAME() return in this formula?

A The sales amount

B The region name

C The email of the current logged-in user

D The table name

Key Result

FILTER table rows where a column equals the region found by LOOKUPVALUE using USERNAME()

Practice

1. What is the main purpose of using USERNAME() in Dynamic Row-Level Security (RLS) in Power BI?

easy

A. To change the report theme dynamically

B. To filter data based on the logged-in user's identity

C. To calculate the total sales amount

D. To create new columns in the data model

Solution

1. Step 1: Understand USERNAME() function

   The USERNAME() function returns the current logged-in user's email or username.

2. Step 2: Apply USERNAME() in Dynamic RLS

   Dynamic RLS uses USERNAME() to filter data so each user sees only their allowed rows.

3. Final Answer:

   To filter data based on the logged-in user's identity -> Option B

4. Quick Check:

   USERNAME() filters data by user [OK]

Hint: USERNAME() filters data by current user identity [OK]

Common Mistakes:

• Thinking USERNAME() creates new columns
• Using USERNAME() to calculate totals
• Confusing USERNAME() with theme settings

2. Which of the following is the correct syntax to create a filter rule for Dynamic RLS using USERNAME() in Power BI?

easy

A. [UserEmail] = USERNAME()

B. FILTER([UserEmail], USERNAME())

C. USERNAME() = [UserEmail]

D. CALCULATE(USERNAME(), [UserEmail])

Solution

1. Step 1: Understand filter rule syntax

   In Dynamic RLS, the filter rule compares a column to the current user using =.

2. Step 2: Identify correct syntax

   The correct syntax is [UserEmail] = USERNAME() to filter rows matching the logged-in user.

3. Final Answer:

   [UserEmail] = USERNAME() -> Option A

4. Quick Check:

   Filter rule uses column = USERNAME() [OK]

Hint: Use column = USERNAME() for filter rules [OK]

Common Mistakes:

• Using USERNAME() on left side of comparison
• Using FILTER() function incorrectly
• Trying to CALCULATE USERNAME()

3. Given a table with a column UserEmail and a Dynamic RLS filter rule [UserEmail] = USERNAME(), what data will a user with email [e-mail] see?

medium

A. Only rows where UserEmail is not [e-mail]

B. All rows regardless of UserEmail

C. Only rows where UserEmail is [e-mail]

D. No rows at all

Solution

1. Step 1: Understand the filter rule effect

   The rule [UserEmail] = USERNAME() filters rows to only those matching the logged-in user's email.

2. Step 2: Apply to user email

   For user [e-mail], only rows with UserEmail = [e-mail] are visible.

3. Final Answer:

   Only rows where UserEmail is [e-mail] -> Option C

4. Quick Check:

   Filter shows rows matching USERNAME() [OK]

Hint: User sees only rows matching their email [OK]

Common Mistakes:

• Assuming user sees all rows
• Thinking user sees rows with different emails
• Believing no rows are shown

4. You wrote this RLS filter rule: FILTER(Users, Users[Email] = USERNAME()). Why does it cause an error in Power BI?

medium

A. FILTER cannot be used directly as a filter rule; it expects a boolean expression

B. USERNAME() is not allowed in RLS rules

C. The column name should be lowercase

D. FILTER requires two arguments

Solution

1. Step 1: Understand RLS filter rule requirements

   RLS filter rules expect a boolean expression, not a table expression like FILTER().

2. Step 2: Identify the error cause

   Using FILTER() returns a table, causing a syntax error in RLS rules.

3. Final Answer:

   FILTER cannot be used directly as a filter rule; it expects a boolean expression -> Option A

4. Quick Check:

   RLS rules need boolean expressions [OK]

Hint: Use boolean expressions, not FILTER(), in RLS rules [OK]

Common Mistakes:

• Using FILTER() instead of boolean condition
• Thinking USERNAME() is disallowed
• Assuming column case matters
• Believing FILTER needs two arguments

5. You want to create Dynamic RLS so that managers see data for their team members, and team members see only their own data. The table has columns UserEmail and ManagerEmail. Which DAX filter rule correctly implements this?

hard

A. USERNAME() = [UserEmail] && USERNAME() = [ManagerEmail]

B. [UserEmail] = USERNAME() && [ManagerEmail] = USERNAME()

C. FILTER(Users, [UserEmail] = USERNAME() || [ManagerEmail] = USERNAME())

D. [UserEmail] = USERNAME() || [ManagerEmail] = USERNAME()

Solution

1. Step 1: Understand the requirement

   Managers should see rows where they are the manager, and users see their own rows.

2. Step 2: Choose correct logical operator

   Use OR (||) to allow either condition: user is the row owner or user is the manager.

3. Step 3: Validate syntax

   [UserEmail] = USERNAME() || [ManagerEmail] = USERNAME() uses correct syntax and logic: [UserEmail] = USERNAME() || [ManagerEmail] = USERNAME().

4. Final Answer:

   [UserEmail] = USERNAME() || [ManagerEmail] = USERNAME() -> Option D

5. Quick Check:

   Use OR (||) to combine user and manager filters [OK]

Hint: Use OR (||) to combine user and manager filters [OK]

Common Mistakes:

• Using AND (&&) instead of OR (||)
• Reversing USERNAME() and column order
• Using FILTER() in RLS rule