fmodel-rust-postgres

Effortlessly transform your domain models into powerful PostgreSQL extensions using our GitHub repository template. With pre-implemented infrastructure and application layers in the framework module, you can focus entirely on your core domain logic while running your models directly within your PostgreSQL database for seamless integration and enhanced performance.

The template includes a demo domain model of a restaurant/order management system, showcasing practical implementation and providing a solid foundation for your own projects.

Actually, the domain model is copied from the traditional application fmodel-rust-demo, demonstrating how to run your unique and single domain model directly within your PostgreSQL database/as extension; or connect the application to the database/traditionally.

Event Sourcing

With event sourcing, we delve deeper by capturing every decision or alteration as an event. Each new transfer or modification to the state is meticulously documented, providing a comprehensive audit trail of all activities. This affords you a 100% accurate historical record of your domain, enabling you to effortlessly traverse back in time and review the state at any given moment.

History is always on!

Technology

This project is using:

• rust programming language to build a high-performance, reliable, and efficient system.
• f{model} rust library to implement tactical Domain-Driven Design patterns, optimised for Event Sourcing.
• pgrx to simplify the creation of custom Postgres extensions and bring logic closer to your data(base).

f{model}

f{model} library provides just enough tactical Domain-Driven Design patterns, optimised for Event Sourcing and CQRS.

• algebraic data types form the structure of our data (commands, state, and events).

• functions/lambda offers the algebra of manipulating the data in a compositional manner, effectively modeling the behavior.

• This leads to modularity in design and a clear separation of the data’s structure and functions/behaviour of the data/entity.

f{model} library offers generic and abstract components to specialize in for your specific case/expected behavior.

Read more

Requirements

• Rust
• PGRX subcommand: cargo install --locked cargo-pgrx
• Then you can run cargo pgrx upgrade in your extension's crate to update its dependencies.
• (Mac os) brew install git icu4c pkg-config
• (Mac os) export PKG_CONFIG_PATH=/opt/homebrew/opt/icu4c/lib/pkgconfig
• Run cargo pgrx init once, to properly configure the pgrx development environment. It downloads the latest releases of supported Postgres versions, configures them for debugging, compiles them with assertions, and installs them to "${PGRX_HOME}". These include all contrib extensions and tools included with Postgres. Other cargo pgrx commands such as run and test will manage and use these installations on your behalf.

No manual Postgres database installation is required.

Test it

Run tests:

cargo pgrx test

Run it

Compile/install extension to a pgrx-managed Postgres instance and start psql console:

cargo pgrx run

Now, you can run the following SQL commands in the psql console:

1. Load the extension:

create extension fmodel_rust_postgres;

2. Send commands to the system:

Observe how the Commands are formatted in JSON format.

Create a restaurant:

select handle('{"type": "CreateRestaurant","identifier": "e48d4d9e-403e-453f-b1ba-328e0ce23737", "name": "Joe", "menu": {"menu_id": "02f09a3f-1624-3b1d-8409-44eff7708210", "items": [{"id": "02f09a3f-1624-3b1d-8409-44eff7708210","name": "supa","price": 10},{"id": "02f09a3f-1624-3b1d-8409-44eff7708210","name": "sarma","price": 20 }],"cuisine": "Vietnamese"}}'::Command);

Place an order at the restaurant:

select handle('{"type": "PlaceOrder","identifier": "e48d4d9e-403e-453f-b1ba-328e0ce23737", "order_identifier": "afd909c6-f8f3-49b2-af7f-833e933cbab4", "line_items": [{"id": "02f09a3f-1624-3b1d-8409-44eff7708210","quantity": 1, "menu_item_id": "02f09a3f-1624-3b1d-8409-44eff7708210", "name": "supa", "price": 10},{"id": "02f09a3f-1624-3b1d-8409-44eff7708210", "quantity": 1, "menu_item_id": "02f09a3f-1624-3b1d-8409-44eff7708210","name": "sarma","price": 20 }]}'::Command);

Confused? Run cargo pgrx help

The structure of the project

The project is structured as follows:

• lib.rs file contains the entry point of the package/crate.
• framework module contains the generalized and parametrized implementation of infrastructure and application layers.
• domain module contains the domain model. It is the core and pure domain logic of the application!!!
• application module contains the application layer. It is the orchestration of the domain model and the infrastructure layer (empty, as it is implemented in the framework module).
• infrastructure module contains the infrastructure layer / fetching and storing data (empty, as it is implemented in the framework module).

The framework module offers a generic implementation of the infrastructure and application layers, which can be reused across multiple domain models. Your focus should be on the domain module, where you can implement your unique domain model. We have provided a demo domain model of a restaurant/order management system to get you started.

Check the tests

The project contains a set of tests that demonstrate how to use the domain model and the framework. You can find them in the root: lib.rs.

You will find a command handler function only, which can handle all the commands of the system! Simple!

References and further reading

• pgrx
• fmodel-rust

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Created with ❤️ by Fraktalio