feat: add fix option to lint command

Author: benfdking

docs/examples/sqlmesh_cli_crash_course.md

@@ -675,6 +675,8 @@ This is a great way to catch SQL issues before wasting runtime in your data ware
 
     ```bash
     sqlmesh lint
+    # or apply fixes automatically
+    sqlmesh lint --fix
     ```
 
 === "Tobiko Cloud"

docs/guides/linter.md

@@ -100,7 +100,7 @@ Place a rule's code in the project's `linter/` directory. SQLMesh will load all
 
 If the rule is specified in the project's [configuration file](#applying-linting-rules), SQLMesh will run it when:
 - A plan is created during `sqlmesh plan`
-- The command `sqlmesh lint` is ran
+- The command `sqlmesh lint` is ran. Add `--fix` to automatically apply available fixes and fail if errors remain.
 
 SQLMesh will error if a model violates the rule, informing you which model(s) violated the rule. In this example, `full_model.sql` violated the `NoMissingOwner` rule, essentially halting execution:
 

docs/reference/cli.md

@@ -636,6 +636,7 @@ Usage: sqlmesh lint [OPTIONS]
 
 Options:
   --model TEXT           A model to lint. Multiple models can be linted.  If no models are specified, every model will be linted.
+  --fix                  Apply fixes for lint errors. Fails if errors remain after fixes are applied.
   --help                 Show this message and exit.
 
 ```

sqlmesh/cli/main.py

@@ -1201,15 +1201,21 @@ def environments(obj: Context) -> None:
     multiple=True,
     help="A model to lint. Multiple models can be linted. If no models are specified, every model will be linted.",
 )
+@click.option(
+    "--fix",
+    is_flag=True,
+    help="Apply fixes for lint errors. Fails if errors remain after fixes are applied.",
+)
 @click.pass_obj
 @error_handler
 @cli_analytics
 def lint(
     obj: Context,
     models: t.Iterator[str],
+    fix: bool,
 ) -> None:
     """Run the linter for the target model(s)."""
-    obj.lint_models(models)
+    obj.lint_models(models, fix=fix)
 
 
 @cli.group(no_args_is_help=True)

sqlmesh/core/context.py

@@ -78,6 +78,7 @@
 from sqlmesh.core.environment import Environment, EnvironmentNamingInfo, EnvironmentStatements
 from sqlmesh.core.loader import Loader
 from sqlmesh.core.linter.definition import AnnotatedRuleViolation, Linter
+from sqlmesh.core.linter.rule import TextEdit, Position
 from sqlmesh.core.linter.rules import BUILTIN_RULES
 from sqlmesh.core.macros import ExecutableOrMacro, macro
 from sqlmesh.core.metric import Metric, rewrite
@@ -3099,6 +3100,7 @@ def lint_models(
         self,
         models: t.Optional[t.Iterable[t.Union[str, Model]]] = None,
         raise_on_error: bool = True,
+        fix: bool = False,
     ) -> t.List[AnnotatedRuleViolation]:
         found_error = False
 
@@ -3116,13 +3118,45 @@ def lint_models(
                     found_error = True
                 all_violations.extend(violations)
 
+        if fix:
+            self._apply_fixes(all_violations)
+            self.refresh()
+            return self.lint_models(models, raise_on_error=raise_on_error, fix=False)
+
         if raise_on_error and found_error:
             raise LinterError(
                 "Linter detected errors in the code. Please fix them before proceeding."
             )
 
         return all_violations
 
+    def _apply_fixes(self, violations: t.List[AnnotatedRuleViolation]) -> None:
+        edits_by_file: t.Dict[Path, t.List[TextEdit]] = {}
+        for violation in violations:
+            for fix in violation.fixes:
+                for create in fix.create_files:
+                    create.path.parent.mkdir(parents=True, exist_ok=True)
+                    create.path.write_text(create.text, encoding="utf-8")
+                for edit in fix.edits:
+                    edits_by_file.setdefault(edit.path, []).append(edit)
+
+        for path, edits in edits_by_file.items():
+            content = path.read_text(encoding="utf-8")
+            lines = content.splitlines(keepends=True)
+
+            def _offset(pos: Position) -> int:
+                return sum(len(lines[i]) for i in range(pos.line)) + pos.character
+
+            for edit in sorted(
+                edits, key=lambda e: (e.range.start.line, e.range.start.character), reverse=True
+            ):
+                start = _offset(edit.range.start)
+                end = _offset(edit.range.end)
+                content = content[:start] + edit.new_text + content[end:]
+                lines = content.splitlines(keepends=True)
+
+            path.write_text(content, encoding="utf-8")
+
     def load_model_tests(
         self, tests: t.Optional[t.List[str]] = None, patterns: list[str] | None = None
     ) -> t.List[ModelTestMetadata]:

tests/cli/test_cli.py

@@ -1328,6 +1328,61 @@ def test_lint(runner, tmp_path):
     assert result.exit_code == 1
 
 
+def test_lint_fix(runner, tmp_path):
+    create_example_project(tmp_path)
+
+    with open(tmp_path / "config.yaml", "a", encoding="utf-8") as f:
+        f.write(
+            """linter:
+    enabled: True
+    rules: ["noselectstar"]
+"""
+        )
+
+    model_path = tmp_path / "models" / "incremental_model.sql"
+    with open(model_path, "r", encoding="utf-8") as f:
+        content = f.read()
+    content = content.replace(
+        "SELECT\n  id,\n  item_id,\n  event_date,\nFROM",
+        "SELECT *\nFROM",
+    )
+    with open(model_path, "w", encoding="utf-8") as f:
+        f.write(content)
+
+    result = runner.invoke(cli, ["--paths", tmp_path, "lint", "--fix"])
+    assert result.exit_code == 0
+    with open(model_path, "r", encoding="utf-8") as f:
+        assert "SELECT *" not in f.read()
+
+
+def test_lint_fix_unfixable_error(runner, tmp_path):
+    create_example_project(tmp_path)
+
+    with open(tmp_path / "config.yaml", "a", encoding="utf-8") as f:
+        f.write(
+            """linter:
+    enabled: True
+    rules: ["noselectstar", "nomissingaudits"]
+"""
+        )
+
+    model_path = tmp_path / "models" / "incremental_model.sql"
+    with open(model_path, "r", encoding="utf-8") as f:
+        content = f.read()
+    content = content.replace(
+        "SELECT\n  id,\n  item_id,\n  event_date,\nFROM",
+        "SELECT *\nFROM",
+    )
+    with open(model_path, "w", encoding="utf-8") as f:
+        f.write(content)
+
+    result = runner.invoke(cli, ["--paths", tmp_path, "lint", "--fix"])
+    assert result.exit_code == 1
+    assert "nomissingaudits" in result.output
+    with open(model_path, "r", encoding="utf-8") as f:
+        assert "SELECT *" not in f.read()
+
+
 def test_state_export(runner: CliRunner, tmp_path: Path) -> None:
     create_example_project(tmp_path)