The problem I need to solve is to store contracts containing a few fields (address, book, num_of_days, borrower_addr, blk_data), blk_data is a transaction list (block number and transaction address).
This question and answer helped me. I would like to share my code as below. Hope this helps.
- Schema definition. See blk_data.
var ContractSchema = new Schema(
{
address: {type: String, required: true, max: 100}, //contract address
// book_id: {type: String, required: true, max: 100}, //book id in the book collection
book: { type: Schema.ObjectId, ref: 'clc_books', required: true }, // Reference to the associated book.
num_of_days: {type: Number, required: true, min: 1},
borrower_addr: {type: String, required: true, max: 100},
// status: {type: String, enum: ['available', 'Created', 'Locked', 'Inactive'], default:'Created'},
blk_data: [{
tx_addr: {type: String, max: 100}, // to do: change to a list
block_number: {type: String, max: 100}, // to do: change to a list
}]
}
);
- Create a record for the collection in the MongoDB. See blk_data.
// Post submit a smart contract proposal to borrowing a specific book.
exports.ctr_contract_propose_post = [
// Validate fields
body('book_id', 'book_id must not be empty.').isLength({ min: 1 }).trim(),
body('req_addr', 'req_addr must not be empty.').isLength({ min: 1 }).trim(),
body('new_contract_addr', 'contract_addr must not be empty.').isLength({ min: 1 }).trim(),
body('tx_addr', 'tx_addr must not be empty.').isLength({ min: 1 }).trim(),
body('block_number', 'block_number must not be empty.').isLength({ min: 1 }).trim(),
body('num_of_days', 'num_of_days must not be empty.').isLength({ min: 1 }).trim(),
// Sanitize fields.
sanitizeBody('*').escape(),
// Process request after validation and sanitization.
(req, res, next) => {
// Extract the validation errors from a request.
const errors = validationResult(req);
if (!errors.isEmpty()) {
// There are errors. Render form again with sanitized values/error messages.
res.status(400).send({ errors: errors.array() });
return;
}
// Create a Book object with escaped/trimmed data and old id.
var book_fields =
{
_id: req.body.book_id, // This is required, or a new ID will be assigned!
cur_contract: req.body.new_contract_addr,
status: 'await_approval'
};
async.parallel({
//call the function get book model
books: function(callback) {
Book.findByIdAndUpdate(req.body.book_id, book_fields, {}).exec(callback);
},
}, function(error, results) {
if (error) {
res.status(400).send({ errors: errors.array() });
return;
}
if (results.books.isNew) {
// res.render('pg_error', {
// title: 'Proposing a smart contract to borrow the book',
// c: errors.array()
// });
res.status(400).send({ errors: errors.array() });
return;
}
var contract = new Contract(
{
address: req.body.new_contract_addr,
book: req.body.book_id,
num_of_days: req.body.num_of_days,
borrower_addr: req.body.req_addr
});
var blk_data = {
tx_addr: req.body.tx_addr,
block_number: req.body.block_number
};
contract.blk_data.push(blk_data);
// Data from form is valid. Save book.
contract.save(function (err) {
if (err) { return next(err); }
// Successful - redirect to new book record.
resObj = {
"res": contract.url
};
res.status(200).send(JSON.stringify(resObj));
// res.redirect();
});
});
},
];
- Update a record. See blk_data.
// Post lender accept borrow proposal.
exports.ctr_contract_propose_accept_post = [
// Validate fields
body('book_id', 'book_id must not be empty.').isLength({ min: 1 }).trim(),
body('contract_id', 'book_id must not be empty.').isLength({ min: 1 }).trim(),
body('tx_addr', 'tx_addr must not be empty.').isLength({ min: 1 }).trim(),
body('block_number', 'block_number must not be empty.').isLength({ min: 1 }).trim(),
// Sanitize fields.
sanitizeBody('*').escape(),
// Process request after validation and sanitization.
(req, res, next) => {
// Extract the validation errors from a request.
const errors = validationResult(req);
if (!errors.isEmpty()) {
// There are errors. Render form again with sanitized values/error messages.
res.status(400).send({ errors: errors.array() });
return;
}
// Create a Book object with escaped/trimmed data
var book_fields =
{
_id: req.body.book_id, // This is required, or a new ID will be assigned!
status: 'on_loan'
};
// Create a contract object with escaped/trimmed data
var contract_fields = {
$push: {
blk_data: {
tx_addr: req.body.tx_addr,
block_number: req.body.block_number
}
}
};
async.parallel({
//call the function get book model
book: function(callback) {
Book.findByIdAndUpdate(req.body.book_id, book_fields, {}).exec(callback);
},
contract: function(callback) {
Contract.findByIdAndUpdate(req.body.contract_id, contract_fields, {}).exec(callback);
},
}, function(error, results) {
if (error) {
res.status(400).send({ errors: errors.array() });
return;
}
if ((results.book.isNew) || (results.contract.isNew)) {
res.status(400).send({ errors: errors.array() });
return;
}
var resObj = {
"res": results.contract.url
};
res.status(200).send(JSON.stringify(resObj));
});
},
];
