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Create schema

We have added our first member to the governance, but there’s still more to complete, as we haven’t defined the data structure for tracking Wine type subjects in this use case.

To progress in the tutorial, we need to define a data structure where we can store information for each wine bottle. In kore, this definition is done using schemas, which allow us to specify the fields, data types, and relationships we want to store, such as harvest number, type of grape, origin of the grape, organic certification, etc.

Schema

Before proceeding, it’s essential to have a clear idea of the information we want to store for each wine bottle. Then, we’ll proceed to create the schema that represents that information appropriately. Below is the schema we have created:

  • Harvest number
  • Type of grape
  • Origin of the grape
  • Certificate authenticating whether it is organic or not
  • Values to be changed in the temperature control event:
    • Timestamp of the last check
    • Value that confirms whether the wine cold chain has been complied with

The schema must be defined in json-schema format so that kore can interpret it correctly. Here’s the schema in this format:

Contract

After declaring our schema, the next step is to create the * contract* as we need a way to update the states of the subjects we declare. Therefore, we’ll create a small project for the contract development, taking reference from what has been declared in this section.

  1. Execute the following command:

    cargo new wine-contract

    This will create an empty Rust project with the specified name, resulting in the following structure:

    .
├── Cargo.toml
└── src
    └── main.rs

  2. We need to modify the Cargo.toml file to include the kore contracts SDK as well as the serde module, which will handle data serialization and deserialization:

    [package]
name = "wine-contract"
version = "0.1.0"
edition = "2021"

[dependencies]
serde = { version = "1.0.152", features = ["derive"] }
kore-sc-rust = { git = "https://github.com/kore-ledger/kore-contract-sdk.git", branch = "main"}

  3. Add the necessary dependencies at the beginning of our file:

    use kore_sc_rust as sdk;
use serde::{Deserialize, Serialize};

  4. Next, we’ll add the data structures that will represent our Wine subjects:

    #[derive(Serialize, Deserialize, Clone, PartialEq)] 
enum Grape {
    CabernetSauvignon,
    Chardonnay,
    PinotNoir,
}

#[derive(Serialize, Deserialize, Clone)]
struct TemperatureControl {
    pub last_check: u32,
    pub temperature_ok: bool,
}

#[derive(Serialize, Deserialize, Clone)]
struct State {
    pub harvest: u32,
    pub grape: Option<Grape>,
    pub origin: String,
    pub organic_certified: Option<bool>,
    pub temperature_control: TemperatureControl,
}

  5. Now is the time to define the state events that can be triggered on our Wine type subjects, which are:

    • Init: Responsible for initializing only those subjects coming from a genesis state.
    • TemperatureControl: In charge of performing the temperature check.
    • OrganicCertification: Responsible for modifying the state of organic certification.

    The added code will be:

    #[derive(Serialize, Deserialize)]
enum StateEvent {
    Init {
        harvest: u32,
        grape: String,
        origin: String,
    },
    TemperatureControl {
        temperature: f32,
        timestamp: u32,
    },
    OrganicCertification {
        fertilizers_control: bool,
        pesticides_control: bool,
        analytics: bool,
        additional_info: String,
    },
}

  6. Add the entry function for the contract, equivalent to the main function:

    #[no_mangle]
pub unsafe fn main_function(state_ptr: i32, event_ptr: i32, is_owner: i32) -> u32 {
    sdk::execute_contract(state_ptr, event_ptr, is_owner, contract_logic)
}

  7. Lastly, add the business logic that will act in each of the cases for the state events declared above:

kore only supports contracts in Base64, so we’ll need to transform ours into that format. For this purpose, Linux has its own utility called base64. Therefore, what we need to do in our main.rs file is:

base64 main.rs

The returned result will be the contract encoded in base64.

Back to kore network

Once we have declared both, the schema and the contract, it’s necessary to emit a Fact event to the governance to add this new information.

Let’s start by verifying the changes we want to make in the governance properties. At this point, our governance should look like the following:

{
    "policies": [
        {
            "approve": {
                "quorum": "MAJORITY"
            },
            "evaluate": {
                "quorum": "MAJORITY"
            },
            "id": "governance",
            "validate": {
                "quorum": "MAJORITY"
            }
        }
    ],
    "schemas": []
}

Now, we need to include the schema, the contract, the genesis state of a subject, as well as the policies that will be applied to them:

To generate the mentioned changes, we will use our kore-Patch tool as follows:

kore-patch '{"policies":[{"approve":{"quorum":"MAJORITY"},"evaluate":{"quorum":"MAJORITY"},"id":"governance","validate":{"quorum":"MAJORITY"}}],"schemas":[]}' '{"policies":[{"approve":{"quorum":"MAJORITY"},"evaluate":{"quorum":"MAJORITY"},"id":"governance","validate":{"quorum":"MAJORITY"}},{"approve":{"quorum":"MAJORITY"},"evaluate":{"quorum":"MAJORITY"},"id":"Wine","validate":{"quorum":"MAJORITY"}}],"schemas":[{"contract":{"raw":"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The result obtained will be as follows:

Now, it’s time to call the method of the governance contract responsible for updating its properties. To do this, we will execute the following:

Once the event is emitted, we need to obtain the new update request. To do this, we run the following:

curl --request GET 'http://localhost:3000/approval-requests?status=Pending'

We copy the value of the id field and accept the governance update request:

curl --request PATCH 'http://localhost:3000/approval-requests/{{PREVIUS-ID}}' \
--header 'Content-Type: application/json' \
--data-raw '{"state": "RespondedAccepted"}'

Finally, we query the governance to verify that the change has been successfully applied. If everything has gone according to plan, it should now have an sn of 2, and the new policy, schema, initial state for Wine subjects, and the contract should be present:

curl --request GET 'http://localhost:3000/subjects/{{GOVERNANCE-ID}}'