Calling macros across projects in dbt - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of calling a macro from another project

Given two dbt projects, project_a and project_b, where project_b defines a macro calculate_discount() that returns price * 0.9. In project_a, you call this macro using {{ project_b.calculate_discount(100) }}. What is the output?

dbt

{% macro calculate_discount(price) %}{{ price * 0.9 }}{% endmacro %}

-- In project_a model:
select {{ project_b.calculate_discount(100) }} as discounted_price

A 100

B 90.0

C SyntaxError: macro not found

D 10.0

💡 Hint

Remember that macros from other projects can be called using the project name as a prefix.

The macro calculate_discount multiplies the input price by 0.9, so calling it with 100 returns 90.0.

🧠 Conceptual

intermediate

Understanding macro namespace in dbt projects

In dbt, when calling a macro from another project, which of the following is true about the macro namespace?

A Macros must be called with the project name prefix to avoid conflicts.

B Macros from other projects are automatically imported without prefix.

C Macros cannot be called across projects in dbt.

D Macros from other projects override local macros without prefix.

💡 Hint

Think about how dbt avoids macro name collisions.

dbt requires using the project name prefix when calling macros from other projects to avoid naming conflicts.

🔧 Debug

advanced

Debugging macro call error across projects

You have a macro format_date() defined in project_x. When calling {{ project_x.format_date('2024-01-01') }} in project_y, you get an error: Runtime Error: 'project_x' is undefined. What is the most likely cause?

A Macros cannot accept string arguments across projects.

B The macro name <code>format_date</code> is misspelled in <code>project_x</code>.

C The <code>project_x</code> is not listed as a dependency in <code>project_y</code>'s <code>packages.yml</code>.

D The macro must be called without the project prefix.

💡 Hint

Check if the other project is properly included as a dependency.

If project_x is not added as a dependency in project_y, dbt cannot find its macros, causing the error.

❓ data_output

advanced

Result of macro generating SQL across projects

In project_main, you call a macro from project_utils that generates a SQL snippet to filter rows where status = 'active'. The macro is called as {{ project_utils.filter_active() }} inside a model's where clause. What is the resulting SQL snippet inserted?

dbt

{% macro filter_active() %}status = 'active'{% endmacro %}

-- Usage in project_main model:
select * from users where {{ project_utils.filter_active() }}

A 'status = active'

B WHERE status = 'active'

C status == 'active'

D status = 'active'

💡 Hint

Macros return raw SQL snippets to be inserted as-is.

The macro returns the condition status = 'active' without quotes or extra keywords, so it fits correctly in the WHERE clause.

🚀 Application

expert

Using macros across projects to standardize date formatting

You want to standardize date formatting across multiple dbt projects by defining a macro format_date(date, format) in project_common. How should you call this macro in project_sales to format the date order_date as 'YYYY-MM-DD'?

A {{ project_common.format_date(order_date, 'YYYY-MM-DD') }}

B {{ format_date(order_date, 'YYYY-MM-DD') }}

C {{ project_sales.format_date(order_date, 'YYYY-MM-DD') }}

D {{ project_common.format_date('order_date', 'YYYY-MM-DD') }}

💡 Hint

Remember to use the project prefix and pass variables correctly.

To call a macro from another project, use the project prefix and pass the variable without quotes.