added documentation for guidelines for creating entity defnitions

README.md

@@ -31,5 +31,6 @@ The key takeaway is that the Alkemio server is designed to be integrated, so tha
 - [Data Management - How data representing the domain model used by Alkemio Platform is managed, including database migrations](docs/DataManagement.md)
 - [Quality Assurance - Details of the test harness around the server and how to execute the test suites](docs/QA.md).
 - [Pushing - How new docker images are published to Dockerhub](docs/Publishing.md)
+- [Database defnitions - Guidelines for creating TypeORM entity definitions](docs/database-defnitions.md)
 
 For other questions / comments please feel free to reach out via the channels listed in the [Alkemio Repo](http://github.com/alkem-io/alkemio) or via [Alkemio organization](https://alkemio.org).

docs/database-definitions.md

@@ -0,0 +1,29 @@
+# Specifying database entity defnitions for usage with the server
+
+Please adhere to the following guidelines when creating TypeORM entity defnitions:
+
+**Defaults**:
+
+- no defaults in entity definitions; set defaults through business logic
+- no defaults to the class fields
+
+**Relations**:
+
+- relations that are not eager need to be defined as optional, since they need to be loaded explicitly
+
+**Lengths**:
+
+- always define length with constants
+- stick to the existing length constants OR in the rear case - create one if nothing fits
+
+| data                | what to use            |
+| ------------------- | ---------------------- |
+| Alkemio identifiers | `char(UUID_LENGTH)`    |
+| enums               | `varchar(ENUM_LENGTH)` |
+| short text          | `varchar(your length)` |
+| long text           | `text`                 |
+| URI, URL            | `varchar(URI_LENGHT)`  |
+
+## Usage
+
+- generate a domain change migration via `migration:generate`