[英]Node.js, Promises & Recursion - Possible?
I want to retrieve transactions from paypal until there is no more transactions to retrieve. 我想从贝宝(Paypal)检索交易,直到没有其他交易可检索。 I would like to do it while using recursive function. 我想在使用递归函数时做到这一点。 I do not manage to figure out how to do it. 我不知道该怎么做。 Is it possible? 可能吗?
I can do the recursion but no to aggregate the transactions and pass them out of the function. 我可以进行递归,但不能汇总事务并将它们传递出函数。
I removed non relevant lines for simplicity. 为了简单起见,我删除了不相关的行。
this.retrieveAllTransactionsBetween = function(end_date, start_date) {
return getTransactions({
STARTDATE: Moment(start_date).format().replace('+00:00', 'Z'),
ENDDATE: Moment(end_date).format().replace('+00:00', 'Z')
})
.then(function(transactions){
if (end) { // test for end of transactions
return [];
}
console.log('finish transactions in iteration where earliest was',earliest.toDate());
return transactions.concat(retrieveAllTransactionsBetween(earliest.toDate(), start_date, customer_id));
})
.catch(function(e){
console.error('getAllTransactionsBetween general error', e);
})
;
};
this.getTransactions = function(dates) {
var stringified_api_call_param = QueryString.stringify(api_call_params);
return new Promise(function(resolve, reject) {
var sequence = Sequence.create();
sequence
.then(function (next) {
api_call_options.headers = {
'Content-Type': 'application/x-www-form-urlencoded',
'Content-Length': Buffer.byteLength(stringified_api_call_param)
}
;
var req = https.request(api_call_options, paypal_helpers.paypalCallbackWrapper(next));
req.on('error', function(e) {
return reject(e.message);
});
req.write(stringified_api_call_param);
req.end();
})
.then(function (next, res){
return resolve(res);
});
});
};
This part is wrong: 这部分是错误的:
return transactions.concat(retrieveAllTransactionsBetween(earliest.toDate(), start_date, customer_id));
You want to wait for the recursive call, .concat
is an array function. 您要等待递归调用, .concat
是一个数组函数。 You should wait for it: 您应该等待:
return retrieveAllTransactionsBetween(earliest.toDate(), start_date, customer_id).
then(function(more){ return transactions.concat(more); });
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