[Backport 1.7.latest] Patch for dbt show for a model with a struct column containing a json datatype

.changes/unreleased/Fixes-20231023-082312.yaml

@@ -0,0 +1,6 @@
+kind: Fixes
+body: Patch for json inline --show
+time: 2023-10-23T08:23:12.245223-06:00
+custom:
+  Author: matt-winkler
+  Issue: "972"

dbt/adapters/bigquery/connections.py

@@ -15,7 +15,7 @@
 
 import google.auth
 import google.auth.exceptions
-import google.cloud.bigquery
+import google.cloud.bigquery as bigquery
 import google.cloud.exceptions
 from google.api_core import retry, client_info
 from google.auth import impersonated_credentials
@@ -63,6 +63,16 @@
 )
 
 
+# Override broken json deserializer for dbt show --inline
+# can remove once this is fixed: https://github.com/googleapis/python-bigquery/issues/1500
+def _json_from_json(value, _):
+    """NOOP string -> string coercion"""
+    return json.loads(value)
+
+
+bigquery._helpers._CELLDATA_FROM_JSON["JSON"] = _json_from_json
+
+
 @lru_cache()
 def get_bigquery_defaults(scopes=None) -> Tuple[Any, Optional[str]]:
     """

tests/functional/adapter/dbt_show/test_dbt_show.py

@@ -1,9 +1,46 @@
+import pytest
 from dbt.tests.adapter.dbt_show.test_dbt_show import BaseShowSqlHeader, BaseShowLimit
 
+from dbt.tests.util import run_dbt
+
+model_with_json_struct = """
+    select *
+    from (
+        select
+  struct<
+    k array<
+        struct<c1 int64, c2 json>
+      >
+  >(
+    [
+      struct(
+        1 as c1,
+        to_json(struct(1 as a)) as c2
+      )
+    ]
+  )
+  as v
+    ) as model_limit_subq
+    limit 5
+    """
+
 
 class TestBigQueryShowLimit(BaseShowLimit):
     pass
 
 
 class TestBigQueryShowSqlHeader(BaseShowSqlHeader):
     pass
+
+
+# Added to check if dbt show works with JSON struct
+# Addresses: https://github.com/dbt-labs/dbt-bigquery/issues/972
+class TestBigQueryShowSqlWorksWithJSONStruct:
+    @pytest.fixture(scope="class")
+    def models(self):
+        return {
+            "json_struct_model.sql": model_with_json_struct,
+        }
+
+    def test_sql_header(self, project):
+        run_dbt(["show", "--select", "json_struct_model"])