dbt-labs/dbt-core · error · minijinja::Error::SerdeDeserializeError

model_constraints: {e}

Error message

model_constraints: {e}

What it means

This error is raised when converting the `model_constraints` Minijinja Value into a typed `Vec<ModelConstraint>` struct via `minijinja_value_to_typed_struct` fails during model materialization in dbt-adapter. The library throws it because the constraints value passed from the Jinja/manifest layer did not deserialize into the expected ModelConstraint shape, meaning the model's constraint definitions are malformed or of an unexpected type. It surfaces as a SerdeDeserializeError wrapping the underlying serde message.

Source

Thrown at crates/dbt-adapter/src/adapter/adapter_impl.rs:4677

                    minijinja::Error::new(
                        minijinja::ErrorKind::InvalidOperation,
                        "existing_columns must contain Column objects",
                    )
                })
            })
            .collect::<Result<Vec<_>, _>>()?;

        let model_columns_map: BTreeMap<String, DbtColumn> =
            minijinja_value_to_typed_struct(model_columns.clone()).map_err(|e| {
                minijinja::Error::new(
                    minijinja::ErrorKind::SerdeDeserializeError,
                    format!("model_columns: {e}"),
                )
            })?;

        let model_constraints_vec: Vec<ModelConstraint> =
            minijinja_value_to_typed_struct(model_constraints.clone()).map_err(|e| {
                minijinja::Error::new(
                    minijinja::ErrorKind::SerdeDeserializeError,
                    format!("model_constraints: {e}"),
                )
            })?;

        let column_refs: Vec<DbtColumnRef> = model_columns_map
            .values()
            .map(|c| Arc::new(c.clone()))
            .collect();

        let (not_nulls, typed_constraints) = if contract_enforced {
            typed_constraint::parse_constraints(&column_refs, &model_constraints_vec).map_err(
                |e| {
                    minijinja::Error::new(
                        minijinja::ErrorKind::InvalidOperation,
                        format!("parse_constraints: {e}"),
                    )
                },

View on GitHub (pinned to 0267ce9170)

Solutions

1. Check the model's YAML `constraints` definitions: each must be a mapping with a valid `type` key (not_null, unique, primary_key, foreign_key, check, etc.)
2. Inspect the underlying serde message appended after 'model_constraints: ' to identify the exact field that failed to deserialize
3. Ensure the caller producing `model_constraints` (manifest node or custom materialization) passes a list of constraint structs, not strings or dicts of another shape
4. Align dbt-core and adapter versions so the ModelConstraint schema matches what the manifest emits

Example fix

// before (model.yml)
constraints:
  - not_null
// after
constraints:
  - type: not_null
    columns: [id]

// caller-side guard
if (!Array.isArray(model_constraints) || model_constraints.some(c => typeof c !== 'object' || c === null || !('type' in c))) {
  throw new Error('model_constraints must be a list of constraint objects each with a `type` field');
}

fn is_model_constraints(v: &Value) -> bool {
    v.clone().try_into_object().map(|o| o.len() >= 0).is_ok()
}

match minijinja_value_to_typed_struct::<Vec<ModelConstraint>>(model_constraints.clone()) {
    Ok(v) => v,
    Err(e) => return Err(format!("model_constraints deserialization failed: {e} - verify constraint YAML shape")),
}

When it happens

Trigger: Calling the adapter's model materialization path (near adapter_impl.rs:4677) with a `model_constraints` value that is not a serializable list of constraint objects — e.g. a dict, a string, or constraints missing required fields like `type`.

Common situations: A model defines `constraints` in YAML with a wrong structure (e.g. constraint given as a plain string instead of a dict with `type:`), a custom materialization passes incompatible data into model_constraints, or a version mismatch between the manifest schema and the ModelConstraint struct.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• {e}
• model_columns: {e}
• get_table_options: Failed to deserialize config: {e}
• get_seed_file_path: Failed to deserialize DbtSeed: {e}
• Failed to deserialize InternalDbtNodeWrapper: {e}

AI-assisted analysis of dbt-labs/dbt-core@0267ce9170 (2026-09-07). Data as JSON: /api/errors/0c496620fda46fb2. Report an issue: GitHub.