API integration guide for students to update their assignment submission or commit to a new module

Update Assignment

A student updates their existing assignment submission with new evidence, or optionally commits to a new module in the same transaction. This is used when a student wants to revise their work before teacher assessment or after a refusal.

Summary

Property	Value
System	Course
Role	Student
Type Key	`assignment_submit`
Build Endpoint	`POST /api/v2/tx/course/student/assignment/update`
DB Sync	Yes
Service Fee	0 ADA
Est. Wallet Cost	~0.33 ADA

The estimated wallet cost breaks down as: transaction fee ~0.28 ADA + minUTxO delta ~0.05 ADA. The minUTxO increases slightly when the on-chain datum grows with updated assignment data.

Build Transaction

Endpoint

POST /api/v2/tx/course/student/assignment/update

Request Body

{
  "alias": "student1",
  "courseId": "a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4",
  "assignmentInfo": "d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c3d4e5",
  "maybeNewSltHash": null,
  "walletData": {
    "usedAddresses": ["addr1qx2fxv..."],
    "changeAddress": "addr1qx2fxv..."
  }
}

Field	Type	Required	Description
`alias`	`string` (Alias)	Yes	The student's access token alias.
`courseId`	`string` (GYMintingPolicyId)	Yes	The 56-character hex course policy ID.
`assignmentInfo`	`string`	Yes	Updated evidence hash — a hash of the student's revised work or a new reference.
`maybeNewSltHash`	`string` (SltHash) or `null`	No	If provided, the student commits to a new module in addition to updating. 64-character hex hash of the target module. Pass `null` or omit if only updating existing evidence.
`walletData`	`WalletData`	No	Object containing `usedAddresses` (string[]) and `changeAddress` (string).

Response

{
  "unsignedTxCBOR": "84a800..."
}

The response contains the unsigned transaction CBOR, ready for the user's wallet to sign.

Register Transaction

After the user signs and submits the transaction, register it with the state machine:

POST /api/v2/tx/register

{
  "tx_hash": "64-char hex hash from wallet.submitTx()",
  "tx_type": "assignment_submit"
}

No metadata is required. On confirmation, the state machine creates or updates the assignment commitment in the database, setting the status to ON_CHAIN. If the student committed on-chain without first saving a draft via the API, the database record is created automatically (upsert behavior).

Endpoint	Description
`GET /api/v2/courses/{course_id}/commitments`	View all assignment commitments for the course, including status

Example: Full Lifecycle

const API_URL = "https://api.andamio.io";

// 1. Build — update evidence for an existing assignment
const buildRes = await fetch(`${API_URL}/api/v2/tx/course/student/assignment/update`, {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "X-API-Key": API_KEY,
    "Authorization": `Bearer ${userJwt}`,
  },
  body: JSON.stringify({
    alias: "student1",
    courseId: "a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4",
    assignmentInfo: "d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c3d4e5",
    maybeNewSltHash: null,
    walletData: {
      usedAddresses: [walletAddress],
      changeAddress: walletAddress,
    },
  }),
});
const { unsignedTxCBOR } = await buildRes.json();

// 2. Sign
const signedTx = await wallet.signTx(unsignedTxCBOR);

// 3. Submit
const txHash = await wallet.submitTx(signedTx);

// 4. Register
await fetch(`${API_URL}/api/v2/tx/register`, {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "X-API-Key": API_KEY,
    "Authorization": `Bearer ${userJwt}`,
  },
  body: JSON.stringify({
    tx_hash: txHash,
    tx_type: "assignment_submit",
  }),
});

// 5. Monitor (SSE)
const events = new EventSource(
  `${API_URL}/api/v2/tx/stream/${txHash}`
);
events.addEventListener("state_change", (e) => {
  const data = JSON.parse(e.data);
  console.log(`State: ${data.old_state} → ${data.new_state}`);
});
events.addEventListener("complete", (e) => {
  const data = JSON.parse(e.data);
  console.log(`Final: ${data.final_state}`);
  events.close();
});