Repository: sqlfluff/sqlfluff
Issue category: Feature Request

Support for DBT's `this.identifier`
### Search before asking

- [X] I searched the [issues](https://github.com/sqlfluff/sqlfluff/issues) and found no similar issues.


### Description

As can be seen in `jinja.py` ([here](https://github.com/sqlfluff/sqlfluff/blob/main/src/sqlfluff/core/templaters/jinja.py#L300)), `ThisEmulator` only supports `name`, `schema`, and `database`. But it should also support `identifier`, as documented [here](https://docs.getdbt.com/reference/resource-properties/identifier), as well as `type`, `is_table`, `is_view`, `is_cte`, and `include()`, as documented [here](https://docs.getdbt.com/reference/dbt-classes#creating-relations). 

Basically, `ref()`, `source()`, and `this` all return a Relation object.

![image](https://github.com/user-attachments/assets/ed1c745f-7606-4c67-a499-18d26e4233a4)

### Use case

Not get SQLFluff errors when using `this.identifier`.

### Dialect

Jinja/DBT

### Are you willing to work on and submit a PR to address the issue?

- [x] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/sqlfluff/sqlfluff/blob/main/CODE_OF_CONDUCT.md)



Functions to edit:
src/sqlfluff/core/templaters/jinja.py:JinjaTemplater._generate_dbt_builtins

Patch:
diff --git a/src/sqlfluff/core/templaters/jinja.py b/src/sqlfluff/core/templaters/jinja.py
index 95bf05d733f..8066ddbced3 100644
--- a/src/sqlfluff/core/templaters/jinja.py
+++ b/src/sqlfluff/core/templaters/jinja.py
@@ -314,21 +314,34 @@ def _generate_dbt_builtins() -> Dict[str, Any]:
         # be configurable somewhere sensible. But for now they're not.
         # TODO: Come up with a better solution.
 
-        class ThisEmulator:
+        class RelationEmulator:
             """A class which emulates the `this` class from dbt."""
 
-            name = "this_model"
+            identifier = "this_model"
             schema = "this_schema"
             database = "this_database"
 
-            def __str__(self) -> str:  # pragma: no cover TODO?
-                return self.name
+            def __init__(self, identifier: str = "this_model") -> None:
+                self.identifier = identifier
+
+            def __call__(self, *args: Any, **kwargs: Any) -> "RelationEmulator":
+                return self
+
+            def __getattr__(self, name: str) -> Union["RelationEmulator", bool]:
+                if name[0:3] == "is_":
+                    return True
+                return self
+
+            def __str__(self) -> str:
+                return self.identifier
 
         dbt_builtins = {
-            "ref": lambda *args: args[-1],
+            "ref": lambda *args, **kwargs: RelationEmulator(args[-1]),
             # In case of a cross project ref in dbt, model_ref is the second
             # argument. Otherwise it is the only argument.
-            "source": lambda source_name, table: f"{source_name}_{table}",
+            "source": lambda source_name, table: RelationEmulator(
+                f"{source_name}_{table}"
+            ),
             "config": lambda **kwargs: "",
             "var": lambda variable, default="": "item",
             # `is_incremental()` renders as True, always in this case.
@@ -337,7 +350,7 @@ def __str__(self) -> str:  # pragma: no cover TODO?
             # We should try to find a solution to that. Perhaps forcing the file
             # to be parsed TWICE if it uses this variable.
             "is_incremental": lambda: True,
-            "this": ThisEmulator(),
+            "this": RelationEmulator(),
         }
         return dbt_builtins
 

Test patch: diff --git a/test/core/templaters/jinja_test.py b/test/core/templaters/jinja_test.py
index 9fccefce213..9c6a722e53d 100644
--- a/test/core/templaters/jinja_test.py
+++ b/test/core/templaters/jinja_test.py
@@ -1790,6 +1790,161 @@ def test_undefined_magic_methods():
     assert ud + ud is ud
 
 
+def test_relation_emulator_magic_methods():
+    """Test all the magic methods defined on RelationEmulator."""
+    dbt_builtins = JinjaTemplater._generate_dbt_builtins()
+
+    # tests for 'this'
+    t = dbt_builtins["this"]
+    assert str(t) == "this_model"
+    assert t.something is t
+    assert str(t.database) == "this_database"
+    assert str(t.schema) == "this_schema"
+    assert str(t.name) == "this_model"
+    assert str(t.identifier) == "this_model"
+    assert str(t.type) == "this_model"
+    assert str(t.something_new) == "this_model"
+    assert t.is_table is True
+    assert t.is_view is True
+    assert t.is_materialized_view is True
+    assert t.is_cte is True
+    assert t.is_dynamic_table is True
+    assert t.is_iceberg_format is True
+    assert t.is_something_new is True
+    assert t.something() is t
+    assert t.something().something() is t
+    assert t.something().something is t
+    assert str(t.include()) == "this_model"
+    assert str(t.include(database=False)) == "this_model"
+    assert str(t.some_new_method()) == "this_model"
+    assert str(t.something().something) == "this_model"
+
+    # tests for 'ref'
+    r = dbt_builtins["ref"]("ref_model")
+    assert str(r) == "ref_model"
+    assert r.something is r
+    assert str(r.database) == "this_database"
+    assert str(r.schema) == "this_schema"
+    assert str(r.name) == "ref_model"
+    assert str(r.identifier) == "ref_model"
+    assert str(r.type) == "ref_model"
+    assert str(r.something_new) == "ref_model"
+    assert r.is_table is True
+    assert r.is_view is True
+    assert r.is_materialized_view is True
+    assert r.is_cte is True
+    assert r.is_dynamic_table is True
+    assert r.is_iceberg_format is True
+    assert r.is_something_new is True
+    assert r.something() is r
+    assert r.something().something() is r
+    assert r.something().something is r
+    assert str(r.include()) == "ref_model"
+    assert str(r.include(database=False)) == "ref_model"
+    assert str(r.some_new_method()) == "ref_model"
+    assert str(r.something().something) == "ref_model"
+
+    # tests for versioned 'ref'
+    r = dbt_builtins["ref"]("ref_model", version=2)
+    assert str(r) == "ref_model"
+    assert r.something is r
+    assert str(r.database) == "this_database"
+    assert str(r.schema) == "this_schema"
+    assert str(r.name) == "ref_model"
+    assert str(r.identifier) == "ref_model"
+    assert str(r.type) == "ref_model"
+    assert str(r.something_new) == "ref_model"
+    assert r.is_table is True
+    assert r.is_view is True
+    assert r.is_materialized_view is True
+    assert r.is_cte is True
+    assert r.is_dynamic_table is True
+    assert r.is_iceberg_format is True
+    assert r.is_something_new is True
+    assert r.something() is r
+    assert r.something().something() is r
+    assert r.something().something is r
+    assert str(r.include()) == "ref_model"
+    assert str(r.include(database=False)) == "ref_model"
+    assert str(r.some_new_method()) == "ref_model"
+    assert str(r.something().something) == "ref_model"
+
+    # tests for 'ref' from project/package
+    r = dbt_builtins["ref"]("package", "ref_model")
+    assert str(r) == "ref_model"
+    assert r.something is r
+    assert str(r.database) == "this_database"
+    assert str(r.schema) == "this_schema"
+    assert str(r.name) == "ref_model"
+    assert str(r.identifier) == "ref_model"
+    assert str(r.type) == "ref_model"
+    assert str(r.something_new) == "ref_model"
+    assert r.is_table is True
+    assert r.is_view is True
+    assert r.is_materialized_view is True
+    assert r.is_cte is True
+    assert r.is_dynamic_table is True
+    assert r.is_iceberg_format is True
+    assert r.is_something_new is True
+    assert r.something() is r
+    assert r.something().something() is r
+    assert r.something().something is r
+    assert str(r.include()) == "ref_model"
+    assert str(r.include(database=False)) == "ref_model"
+    assert str(r.some_new_method()) == "ref_model"
+    assert str(r.something().something) == "ref_model"
+
+    # tests for versioned 'ref' from project/package
+    r = dbt_builtins["ref"]("package", "ref_model", version=2)
+    assert str(r) == "ref_model"
+    assert r.something is r
+    assert str(r.database) == "this_database"
+    assert str(r.schema) == "this_schema"
+    assert str(r.name) == "ref_model"
+    assert str(r.identifier) == "ref_model"
+    assert str(r.type) == "ref_model"
+    assert str(r.something_new) == "ref_model"
+    assert r.is_table is True
+    assert r.is_view is True
+    assert r.is_materialized_view is True
+    assert r.is_cte is True
+    assert r.is_dynamic_table is True
+    assert r.is_iceberg_format is True
+    assert r.is_something_new is True
+    assert r.something() is r
+    assert r.something().something() is r
+    assert r.something().something is r
+    assert str(r.include()) == "ref_model"
+    assert str(r.include(database=False)) == "ref_model"
+    assert str(r.some_new_method()) == "ref_model"
+    assert str(r.something().something) == "ref_model"
+
+    # tests for 'source'
+    s = dbt_builtins["source"]("sourcename", "tablename")
+    assert str(s) == "sourcename_tablename"
+    assert s.something is s
+    assert str(s.database) == "this_database"
+    assert str(s.schema) == "this_schema"
+    assert str(s.name) == "sourcename_tablename"
+    assert str(s.identifier) == "sourcename_tablename"
+    assert str(s.type) == "sourcename_tablename"
+    assert str(s.something_new) == "sourcename_tablename"
+    assert s.is_table is True
+    assert s.is_view is True
+    assert s.is_materialized_view is True
+    assert s.is_cte is True
+    assert s.is_dynamic_table is True
+    assert s.is_iceberg_format is True
+    assert s.is_something_new is True
+    assert s.something() is s
+    assert s.something().something() is s
+    assert s.something().something is s
+    assert str(s.include()) == "sourcename_tablename"
+    assert str(s.include(database=False)) == "sourcename_tablename"
+    assert str(s.some_new_method()) == "sourcename_tablename"
+    assert str(s.something().something) == "sourcename_tablename"
+
+
 @pytest.mark.parametrize(
     "sql_path, expected_renderings",
     [