From c8e58f7cb8a6cd8c0ca4768510c65d1fa210003d Mon Sep 17 00:00:00 2001
From: George Sittas <giwrgos.sittas@gmail.com>
Date: Thu, 28 Aug 2025 16:14:44 +0300
Subject: [PATCH] Fix: properly handle empty `vars` mapping in dbt_project.yml

---
 sqlmesh/dbt/project.py   |  2 +-
 tests/dbt/test_config.py | 57 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/sqlmesh/dbt/project.py b/sqlmesh/dbt/project.py
index 581660943a..4af30958f5 100644
--- a/sqlmesh/dbt/project.py
+++ b/sqlmesh/dbt/project.py
@@ -99,7 +99,7 @@ def load(cls, context: DbtContext, variables: t.Optional[t.Dict[str, t.Any]] = N
             package = package_loader.load(path.parent)
             packages[package.name] = package
 
-        all_project_variables = {**project_yaml.get("vars", {}), **(variable_overrides or {})}
+        all_project_variables = {**(project_yaml.get("vars") or {}), **(variable_overrides or {})}
         for name, package in packages.items():
             package_vars = all_project_variables.get(name)
 
diff --git a/tests/dbt/test_config.py b/tests/dbt/test_config.py
index 852ad02d5e..a79ee59b69 100644
--- a/tests/dbt/test_config.py
+++ b/tests/dbt/test_config.py
@@ -1090,3 +1090,60 @@ def test_sqlmesh_model_kwargs_columns_override():
         {"c": ColumnConfig(name="c", data_type="uinteger")},
     )
     assert kwargs.get("columns") == {"c": exp.DataType.build(exp.DataType.Type.UINT)}
+
+
+def test_empty_vars_config(tmp_path):
+    """Test that a dbt project can be loaded with an empty vars config."""
+    dbt_project_dir = tmp_path / "test_project"
+    dbt_project_dir.mkdir()
+
+    # Create a minimal dbt_project.yml with empty vars
+    dbt_project_yml = dbt_project_dir / "dbt_project.yml"
+    dbt_project_yml.write_text("""
+name: test_empty_vars
+
+version: "1.0.0"
+config-version: 2
+
+profile: test_empty_vars
+
+models:
+  +start: Jan 1 2022
+
+# Empty vars section - various ways to specify empty
+vars:
+    """)
+
+    # Create a minimal profiles.yml
+    profiles_yml = dbt_project_dir / "profiles.yml"
+    profiles_yml.write_text("""
+test_empty_vars:
+  outputs:
+    dev:
+      type: duckdb
+      schema: test
+  target: dev
+    """)
+
+    # Create a simple model
+    model = dbt_project_dir / "models" / "some_model.sql"
+    model.parent.mkdir(parents=True, exist_ok=True)
+    model.write_text("SELECT 1 as id")
+
+    # Load the project
+    from sqlmesh.dbt.context import DbtContext
+    from sqlmesh.dbt.project import Project
+    from sqlmesh.core.config import Config
+
+    context = DbtContext(project_root=dbt_project_dir, sqlmesh_config=Config())
+
+    # This should not raise an error even with empty vars
+    project = Project.load(context)
+
+    # Verify the project loaded successfully
+    assert project.packages["test_empty_vars"] is not None
+    assert project.packages["test_empty_vars"].name == "test_empty_vars"
+
+    # Verify the variables are empty (not causing any issues)
+    assert project.packages["test_empty_vars"].variables == {}
+    assert project.context.variables == {}