dbt-labs/dbt-core · error

relation must be an object

Error message

relation must be an object

What it means

downcast_value_to_dyn_base_relation received a minijinja Value that is not an object at all (as_object() returned None) — the argument passed from Jinja to relation-taking adapter methods (drop_relation, truncate_relation, rename_relation, expand_target_column_types, cache handling) is a scalar/string/undefined rather than a relation wrapper.

Solutions

1. Pass an actual relation object (api.Relation.create(...) / this) from the Jinja call site
2. Guard with is_defined/as_object checks in the macro before calling adapter methods
3. Include the received value's type in the error to speed up template debugging

When it happens

Trigger: Thrown at crates/dbt-adapter/src/cast_util.rs:19 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of dbt-labs/dbt-core@0267ce9170 (2026-09-07). Data as JSON: /api/errors/0675ab72ba406d6b. Report an issue: GitHub.

Appendix: source

Thrown at crates/dbt-adapter/src/cast_util.rs:19

//! A set of util functions for casting from/to Value
use crate::relation::RelationObject;

use dbt_schemas::schemas::relations::base::BaseRelation;

use std::file;
use std::sync::Arc;

pub const THIS_RELATION_KEY: &str = "__this__";

pub fn downcast_value_to_dyn_base_relation(
    value: &minijinja::Value,
) -> Result<Arc<dyn BaseRelation>, minijinja::Error> {
    if let Some(relation_object) = value.downcast_object::<RelationObject>() {
        Ok(relation_object.inner())
    } else if let Some(relation_object) = value
        .as_object()
        .ok_or_else(|| {
            minijinja::Error::new(
                minijinja::ErrorKind::InvalidOperation,
                "relation must be an object",
            )
        })?
        .get_value(&minijinja::Value::from(THIS_RELATION_KEY))
    {
        Ok(relation_object
            .downcast_object::<RelationObject>()
            .ok_or_else(|| {
                minijinja::Error::new(
                    minijinja::ErrorKind::InvalidOperation,
                    "this must be a BaseRelation object",
                )
            })?
            .inner())
    } else {
        Err(minijinja::Error::new(
            minijinja::ErrorKind::InvalidOperation,

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