dbt-labs/dbt-core · error · InvalidOperation

diff_of_two_dicts requires a dict_b argument

Error message

diff_of_two_dicts requires a dict_b argument

What it means

diff_of_two_dicts validates that a value for dict_b is available, either via the dict_b kwarg or the second positional argument. When neither is present the function throws this InvalidOperation error. It complements the dict_a check at base.rs:614.

Source

Thrown at crates/dbt-jinja-utils/src/functions/base.rs:626

        }

        let dict_a_arg = match (kwargs.get("dict_a"), args.first()) {
            (Ok(value), _) => value,
            (_, Some(value)) => value,
            _ => {
                return Err(Error::new(
                    ErrorKind::InvalidOperation,
                    "diff_of_two_dicts requires a dict_a argument",
                ));
            }
        }
        .clone();

        let dict_b_arg = match (kwargs.get("dict_b"), args.get(1)) {
            (Ok(value), _) => value,
            (_, Some(value)) => value,
            _ => {
                return Err(Error::new(
                    ErrorKind::InvalidOperation,
                    "diff_of_two_dicts requires a dict_b argument",
                ));
            }
        }
        .clone();

        let dict_a = parse_dict_of_lists(&dict_a_arg)?;
        let dict_b = parse_dict_of_lists(&dict_b_arg)?;

        // Convert dict_b to lowercase for case-insensitive comparison.
        // IndexMap preserves insertion order so `diff_of_two_dicts` matches
        // Python's dict semantics (iteration follows dict_a's insertion order),
        // which apply_grants macros rely on for deterministic REVOKE/GRANT order.
        let mut dict_b_lowered: IndexMap<String, Vec<String>> = IndexMap::new();
        for (key, value_list) in dict_b {
            dict_b_lowered.insert(
                key.to_lowercase(),

View on GitHub (pinned to 0267ce9170)

Solutions

1. Supply the second dict positionally: diff_of_two_dicts(a, b)
2. Or pass dict_b=... explicitly alongside dict_a
3. If comparing against an empty dict intentionally, pass {} as the second argument

Example fix

// before
{% set diff = diff_of_two_dicts(my_dict) %}
// after
{% set diff = diff_of_two_dicts(my_dict, {}) %}

{% if dict_b is not defined %}
  {{ exceptions.raise_compiler_error('dict_b is required for diff_of_two_dicts in ' ~ this) }}
{% endif %}

{% macro is_dict(x) %}{{ return(x is defined and x is mapping) }}{% endmacro %}

When it happens

Trigger: Calling diff_of_two_dicts(a) with a single positional dict and no dict_b kwarg — the most common shape that reaches this branch. Also diff_of_two_dicts(dict_a=a) with only the dict_a kwarg.

Common situations: Developers assuming the function diffs against an implicit empty dict or the model config; partial refactors where the second dict argument was deleted; passing only one dict to compare 'with nothing'.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• diff_of_two_dicts requires a dict_a argument
• write function requires payload argument
• describe_dynamic_table is not supported by the {} adapter
• describe_interactive_table is not supported by the {} adapte
• get_csv_data requires agate_table argument

AI-assisted analysis of dbt-labs/dbt-core@0267ce9170 (2026-09-07). Data as JSON: /api/errors/6970bc229048420a. Report an issue: GitHub.