added the ability to set and using environment variables. Added exa… (#…

…17)

* added the ability to set  and  using environment variables. Added example of dynamic  in readme

---------

Co-authored-by: Naya Verdier <[email protected]>

.gitignore

@@ -27,3 +27,4 @@ coverage.xml
 
 # mypy
 .mypy_cache/
+.idea

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## 0.14.0 2023-12-21
+
+- Add support for `__table_region__` and `__table_host__` to be lazy callables
+- Default `__table_region__` and `__table_host__` to `DYNTASTIC_REGION` and
+  `DYNTASTIC_HOST` environment variable if not otherwise defined
+
 ## 0.13.1 2023-11-21
 
 - Fix import error when using `pydantic>=2.5`

README.md

@@ -69,10 +69,6 @@ p.model_dump_json()
 
 ```
 
-To explicitly define an AWS region or DynamoDB endpoint url (for using a local
-dynamodb docker instance, for example), set `__table_region__` or
-`__table_host__`
-
 ### Inserting into DynamoDB
 
 Using the `Product` example from above, simply:
@@ -362,6 +358,61 @@ index2 = Index("my_field", "my_second_field", index_name="my_field_my_second_fie
 MyModel.create_table(index1, index2)
 ```
 
+## Dynamic table names
+In some circumstances you may want the table name to be defined dynamically.
+This can be done by setting the `__table_name__` attribute to a Callable that returns the table name
+from the source of your choice. In the example below, we are using an environment variable. 
+
+```python
+import os
+from dyntastic import Dyntastic
+
+os.environ["MY_TABLE_NAME"] = "my_table"
+
+class Product(Dyntastic):
+    __table_name__ = lambda: os.getenv("MY_TABLE_NAME")
+    __hash_key__ = "product_id"
+
+    product_id: str
+```
+
+## Custom dynamodb endpoint or region for local development
+To explicitly define an AWS region or DynamoDB endpoint url (for using a local
+dynamodb docker instance, for example), set `__table_region__` or `__table_host__`.
+These attributes can be a string or a Callable that returns a string.
+
+```python
+from dyntastic import Dyntastic
+
+class Product(Dyntastic):
+    __table_name__ = "products"
+    __table_region__ = "us-east-1"
+    __table_host__ = "http://localhost:8000"
+    __hash_key__ = "product_id"
+
+    product_id: str
+```
+
+You can also set the environment variables `DYNTASTIC_HOST` and/or `DYNTASTIC_REGION` to control the behavior
+of the underlying boto3 client and resource objects. 
+
+*Note*: if both the environment variables and the class attributes are set,
+the class attributes will take precedence. 
+
+```python
+import os
+from dyntastic import Dyntastic
+
+os.environ["DYNTASTIC_HOST"] = "http://localhost:8000"
+os.environ["DYNTASTIC_REGION"] = "us-east-1"
+
+class Product(Dyntastic):
+    __table_name__ = "products"
+    __hash_key__ = "product_id"
+
+    product_id: str
+```
+
 ## Contributing / Developer Setup
 
 Make sure [`just`](https://github.com/casey/just) is installed on your system

dyntastic/main.py

@@ -1,3 +1,4 @@
+import os
 import time
 import warnings
 from decimal import Decimal
@@ -25,7 +26,6 @@
 
 __version__ = _metadata.version("dyntastic")
 
-
 _T = TypeVar("_T", bound="Dyntastic")
 
 
@@ -441,6 +441,20 @@ def _resolve_table_name(cls) -> str:
         else:
             return cls.__table_name__
 
+    @classmethod
+    def _resolve_table_region(cls) -> Optional[str]:
+        if callable(cls.__table_region__):
+            return cls.__table_region__()
+        else:
+            return cls.__table_region__ or os.getenv("DYNTASTIC_REGION")
+
+    @classmethod
+    def _resolve_table_host(cls) -> Optional[str]:
+        if callable(cls.__table_host__):
+            return cls.__table_host__()
+        else:
+            return cls.__table_host__ or os.getenv("DYNTASTIC_HOST")
+
     @classmethod
     def _dynamodb_type(cls, key: str) -> str:
         # Note: pragma nocover on the following line as coverage marks the ->exit branch as
@@ -483,11 +497,13 @@ def _dyntastic_key_dict(self):
     def _dynamodb_boto3_kwargs(cls):
         kwargs = {}
 
-        if cls.__table_region__:
-            kwargs["region_name"] = cls.__table_region__
+        region = cls._resolve_table_region()
+        if region:
+            kwargs["region_name"] = region
 
-        if cls.__table_host__:
-            kwargs["endpoint_url"] = cls.__table_host__
+        host = cls._resolve_table_host()
+        if host:
+            kwargs["endpoint_url"] = host
 
         return kwargs
 

setup.py

@@ -32,7 +32,7 @@
 
 setup(
     name="dyntastic",
-    version="0.13.1",
+    version="0.14.0",
     description=description,
     long_description=long_description,
     long_description_content_type="text/markdown",

tests/test_subclass.py

@@ -1,3 +1,5 @@
+from unittest.mock import patch
+
 import pytest
 from pydantic import Field
 
@@ -108,3 +110,97 @@ class MyObject(Dyntastic):
     resource = MyObject._dynamodb_resource()
     assert client.meta.endpoint_url == "http://localhost:8000"
     assert resource.meta.client.meta.endpoint_url == "http://localhost:8000"
+
+
+@patch.dict("os.environ", {"DYNTASTIC_HOST": "http://localhost:8000"})
+def test_table_host_env():
+    class MyObject(Dyntastic):
+        __table_name__ = "my_object"
+        __hash_key__ = "my_hash_key"
+
+        my_hash_key: str
+
+    client = MyObject._dynamodb_client()
+    resource = MyObject._dynamodb_resource()
+    assert client.meta.endpoint_url == "http://localhost:8000"
+    assert resource.meta.client.meta.endpoint_url == "http://localhost:8000"
+
+
+@patch.dict("os.environ", {"DYNTASTIC_HOST": "http://some-other-host"})
+def test_table_host_meta_and_env():
+    class MyObject(Dyntastic):
+        __table_name__ = "my_object"
+        __hash_key__ = "my_hash_key"
+        __table_host__ = "http://localhost:8000"
+
+        my_hash_key: str
+
+    assert MyObject.__table_host__ == "http://localhost:8000"
+    client = MyObject._dynamodb_client()
+    resource = MyObject._dynamodb_resource()
+    assert client.meta.endpoint_url == "http://localhost:8000"
+    assert resource.meta.client.meta.endpoint_url == "http://localhost:8000"
+
+
+def test_table_region():
+    class MyObject(Dyntastic):
+        __table_name__ = "my_object"
+        __hash_key__ = "my_hash_key"
+        __table_region__ = "fake-region"
+
+        my_hash_key: str
+
+    assert MyObject.__table_region__ == "fake-region"
+    client = MyObject._dynamodb_client()
+    resource = MyObject._dynamodb_resource()
+    assert client.meta.region_name == "fake-region"
+    assert resource.meta.client.meta.region_name == "fake-region"
+
+
+@patch.dict("os.environ", {"DYNTASTIC_REGION": "fake-region"})
+def test_table_region_env():
+    class MyObject(Dyntastic):
+        __table_name__ = "my_object"
+        __hash_key__ = "my_hash_key"
+
+        my_hash_key: str
+
+    client = MyObject._dynamodb_client()
+    resource = MyObject._dynamodb_resource()
+    assert client.meta.region_name == "fake-region"
+    assert resource.meta.client.meta.region_name == "fake-region"
+
+
+@patch.dict("os.environ", {"DYNTASTIC_REGION": "other-region"})
+def test_table_region_meta_and_env():
+    class MyObject(Dyntastic):
+        __table_name__ = "my_object"
+        __hash_key__ = "my_hash_key"
+        __table_region__ = "fake-region"
+
+        my_hash_key: str
+
+    assert MyObject.__table_region__ == "fake-region"
+    client = MyObject._dynamodb_client()
+    resource = MyObject._dynamodb_resource()
+    assert client.meta.region_name == "fake-region"
+    assert resource.meta.client.meta.region_name == "fake-region"
+
+
+def test_table_host_region_callable():
+    """Disabling flake rule "E371: do not assign a lambda expression, use a def" for this test"""
+
+    class MyObject(Dyntastic):
+        __table_name__ = "my_object"
+        __hash_key__ = "my_hash_key"
+        __table_host__ = lambda: "http://localhost:8000"  # noqa #E371 do not assign a lambda expression, use a def
+        __table_region__ = lambda: "fake-region"  # noqa #E371 do not assign a lambda expression, use a def
+
+        my_hash_key: str
+
+    client = MyObject._dynamodb_client()
+    resource = MyObject._dynamodb_resource()
+    assert client.meta.endpoint_url == "http://localhost:8000"
+    assert resource.meta.client.meta.endpoint_url == "http://localhost:8000"
+    assert client.meta.region_name == "fake-region"
+    assert resource.meta.client.meta.region_name == "fake-region"