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Welcome to the Application that serves as one of the backends for the Cambiatus Ecosystem, One of the backends since this is the one that contains the data in a manner than is easy to index and search.

In the context of the diagram below which is a high level view of how the data flows in our application this application serves as the datastore using a Postgres db and as the API using Phoenix running a Graphql Server

At a high level this is a database that is synced to events on an blockchain which then presents a Graphql API that makes it simpler to consume the information from the blockchain. At the moment this is a normal database with the the usual CRUD actions however creation and updating happens as a result of events that trigger writes and updates to our database.

The intention down the line is to make this database a write only database in an Event Sourced structure which will enable us to replay events and give us much more observability.

Here we have information on the type of technologies we use on our project, enjoy!

Language & Framework

• Elixir language main documentation page
• Phoenix framework main documentation page

Query language

• Intro to GraphQL

Here are some notable packages related to GraphQL:

• Ecto is Elixir's database wrapper that works around GraphQL

• Absinthe package GraphQL toolkit for Elixir

Here is our GraphQL wiki page

Databases

• Postgres main documentation page

• EOS Blockchain main documentation page

  • Here is our documentation on how we use EOS blockchain

To build and run this application locally follow the following steps!

Step 1

Clone this repository by running

git clone [email protected]:cambiatus/backend.git

Step 2

Change into the new repository directory by running

cd backend

Step 3

The system uses ImageMagick for ensuring that the process of image uploads runs properly and Mogrify (dependency package) is dependent on this. Here are instructions for installing it.

Install dependencies by running

mix deps.get

Step 4

Create a database by running

mix ecto.create

Note: you may need to change the database user and password variables values in the config/test.exs and config/dev.exs to ensure proper connection with Postgres.

Then, run the current database migrations using

mix ecto.migrate

Step 5

Once the ecto migration is done successfully, run tests via the test command below

mix test

Note: Ideally the test results should exit with a status of 0 failed tests

Step 6

Lastly, run the server using the following command

mix phx.server

Now you can visit localhost:4000 from your browser.

#Boom! Now you can hack away!

When you are ready to make your first contribution please check out our Contribution guide, this will get your up to speed on where and how to start.

Once done with the contributing guide, here are some developing tips to help you:

Code Formatting

• To ensure code consistency we use linter testing, static code analysis for the approval of our Pull Requests. Always run mix credo before pushing your commits.

• Another critical formatting command is mix format, which formats a specific file according to the Elixir language formatting rules command. There are IDE specific extensions and settings that you could use to have automated formatting. Here is one Elixir vscode example for this.

Files To Not Commit Changes

Changes related to local Postgres database credentials must not be commited to the repo

Here one way of how to not commit changes related to your local database connection credentials (user & password) to dev.exs and text.exs files:

• After you finished working on a development and before you commit your changes, select dev.exs and text.exs files on your IDE or Git Desktop.

  • IF the only changes to these files are related to the local database connection credentials.

    • Then, revert all the changes on these two files (dev.exs and text.exs).

  • ELSE

    • ONLY revert the changes related to the local database connection credentials on these two files (dev.exs and text.exs).

  • HERE is another alternative using the exclude command.

• Here is our Frontend (Elm) repo. We use Elm which is an awesome functional language to play with!

• Here is our Smart Contract (EOS) repo. We use EOS which is an awesome blockchain and uses C++ as language to play with!

• Our wiki page has several development resources to help you during your collaboration.