fix(aredis_om/model/model.py): lazy DB connections

See <https://github.com/redis/redis-om-python/pull/543>.

aredis_om/model/model.py

@@ -25,6 +25,8 @@ from typing import (
 )
 
 from more_itertools import ichunked
+from redis import Redis
+from redis.asyncio import Redis as RedisAsync
 from redis.commands.json.path import Path
 from redis.exceptions import ResponseError
 from typing_extensions import Protocol, get_args, get_origin
@@ -1255,9 +1257,7 @@ class ModelMeta(ModelMetaclass):
                 base_meta, "primary_key_pattern", "{pk}"
             )
         if not getattr(new_class._meta, "database", None):
-            new_class._meta.database = getattr(
-                base_meta, "database", get_redis_connection()
-            )
+            new_class._meta.database = getattr(base_meta, "database", None)
         if not getattr(new_class._meta, "encoding", None):
             new_class._meta.encoding = getattr(base_meta, "encoding")
         if not getattr(new_class._meta, "primary_key_creator_cls", None):
@@ -1282,6 +1282,7 @@ class ModelMeta(ModelMetaclass):
 
 class RedisModel(BaseModel, abc.ABC, metaclass=ModelMeta):
     pk: Optional[str] = Field(default=None, primary_key=True)
+    _conn: Optional[Union[Redis, RedisAsync]] = None
 
     Meta = DefaultMeta
 
@@ -1370,7 +1371,19 @@ class RedisModel(BaseModel, abc.ABC, metaclass=ModelMeta):
 
     @classmethod
     def db(cls):
-        return cls._meta.database
+        if not cls._conn:
+            conn = (
+                cls._meta.database()
+                if callable(cls._meta.database)
+                else cls._meta.database or get_redis_connection()
+            )
+            if not has_redis_json(conn):
+                log.error(
+                    "Your Redis instance does not have the RedisJson module "
+                    "loaded. JsonModel depends on RedisJson."
+                )
+            cls._conn = conn
+        return cls._conn
 
     @classmethod
     def find(
@@ -1674,14 +1687,6 @@ class JsonModel(RedisModel, abc.ABC):
         # Generate the RediSearch schema once to validate fields.
         cls.redisearch_schema()
 
-    def __init__(self, *args, **kwargs):
-        if not has_redis_json(self.db()):
-            log.error(
-                "Your Redis instance does not have the RedisJson module "
-                "loaded. JsonModel depends on RedisJson."
-            )
-        super().__init__(*args, **kwargs)
-
     async def save(
         self: "Model", pipeline: Optional[redis.client.Pipeline] = None
     ) -> "Model":