Incorporate modules in the dapp

Let’s put this into practice by organizing code into smaller modules. First, a folder named news_feed is created and a module.rell file is added inside it:

src/news_feed/module.rell

module;

Next, everything from this module is imported into main.rell by adding the following line:

src/main.rell

import news_feed.*;

Then, a file named model.rell is created in the src/news_feed folder and the entity definitions from the main file are moved into this new file:

src/news_feed/model.rell

entity user {
  mutable name;
  key id: byte_array;
  key account;
}

entity follower {
  index user;
  index follower: user;
  key user, follower;
}

entity post {
  timestamp = op_context.last_block_time;
  index user;
  content: text;
}

Now, the import statement for the account entity from the ft-library is shifted to the module.rell file. This arrangement allows all files within the module to access it:

src/news_feed/module.rell

module;

import lib.ft4.accounts.{ account };
import lib.ft4.auth;

The auth_handler is moved to src/news_feed/auth.rell and post_dto to src/news_feed/dto.rell. If preferred, the require_user and format_user utility functions can also be added directly to module.rell. The queries are placed in src/news_feed/queries.rell, and the operations are relocated to src/news_feed/operations.rell.

After these changes, the module.rell file in the news_feed module should look like this:

src/news_feed/module.rell

module;

import lib.ft4.accounts.{ account };
import lib.ft4.auth;

function require_user(id: byte_array) = require(user @? { id }, "User with id %s does not exist".format(id));
function format_user(user) = "%s#%s".format(user.name, user.id.to_hex().sub(0, 5));

With the proper imports in place, the main.rell file should now only include the create_user operation, which is beneficial for testing purposes.

Next, a new module called test_operations is created in the test folder by creating a file there and declaring it as a module:

src/test/test_operations.rell

module;

import lib.ft4.core.accounts. { create_account_with_auth };
import lib.ft4.accounts.{ single_sig_auth_descriptor };
import ^^.news_feed.{ user };

operation create_user(name, pubkey) {
    val account = create_account_with_auth(single_sig_auth_descriptor(pubkey, set(["A", "T", "S"])));
    create user ( name, pubkey, account );
}

In the test file, this module is explicitly imported, possibly using relative imports:

src/test/news_feed_test.rell

import ^.test_operations.{ create_user };

It has now been shown how to effectively structure the project using Rell modules. The file structure should resemble the following:

rell/src
├─ main.rell
├─ news_feed
│  ├─ auth.rell
│  ├─ dto.rell
│  ├─ model.rell
│  ├─ module.rell
│  ├─ operations.rell
│  └─ queries.rell
├─ registration
│  └─ module.rell
└─ test
   ├─ news_feed_test.rell
   ├─ registration_test.rell
   └─ test_operations.rell