我正在使用node-crontab来运行脚本. fs.writeFile第一次覆盖循环运行,但之后是附加数据.我已经尝试在写入之前删除该文件,但是执行相同操作,第一次删除它,但在随后的运行中开始附加.我该怎么办？
这是脚本：我省略了一些环境变量…
var jobId = crontab.scheduleJob('* * * * *',function() {
//Gettting system date and adding leading zeros when are single digits. I need this to build the get request with date filters.
var d = new Date();
var nday = d.getDate();
var nmonth = d.getMonth();
var nhour = d.getHours();
var nmin = d.getMinutes();
var nfullyear = d.getFullYear();
if (nday < 10) {
nday = '0' + nday;
};
var nmin = nmin - 1;
if (nmin < 10) {
nmin = '0' + nmin;
};
if (nhour < 10) {
nhour = '0' + nhour;
};
var nmonth = nmonth + 1;
if (nmonth < 10) {
nmonth = '0' + nmonth;
};
var options = {
url: 'https://credentials@api.comettracker.com/v1/gpsdata' + '?fromdate=' + nfullyear + '-' + nmonth + '-' + nday + 'T' + nhour + '%3a' + nmin + '%3a' + '00',method: 'GET',rejectUnauthorized: !debug
};
// HTTP get request
request(options,function(error,response,body) {
if (error) throw new Error(error);
var result = JSON.parse(body)['gps-recs'];
console.log(result.length);
//create .csv file
buildCSV(result);
});
});
function buildCSV(result) {
//adding headers
csvFile = csvFile.concat('UserNumber' + ',' + 'UserTiMetag' + ',' + 'Latitude' + ',' + 'Longitude' + ',' + 'SpeedMph' + ',' + 'Heading' + ',' + 'Status' + '\r\n');
// loop runs result.length times
for (var i = 0; i < result.length; i++) {
csvFile = csvFile.concat(result[i].UserInfo.UserNumber + ',' + result[i].UserTiMetag + ',' + result[i].Latitude + ',' + result[i].Longitude + ',' + result[i].SpeedMph + ',' + result[i].Heading + ',' + result[i].Status + '\r\n');
};
//delete file.csv first
console.log('before unlink: ');
fs.unlink('file.csv',function(err){
if (err) throw err;
else {
console.log('file deleted');
console.log(csvFile);
fs.writeFile('file.csv',csvFile,function(err) {
if (err) throw err;
console.log('file saved');
});
};
});
};
解决方法
一件事当我运行你的代码,如果没有文件存在首先得到一个错误.请参阅下面的修复.
为了确保你正在写,你可以明确地将这个写入标志提供给options参数：
console.log('before unlink: ');
fs.unlink('file.csv',function(err){
// Ignore error if no file already exists
if (err && err.code !== 'ENOENT')
throw err;
var options = { flag : 'w' };
fs.writeFile('file.csv',options,function(err) {
if (err) throw err;
console.log('file saved');
});
});
btw,fs.unlink()不是真的需要,因为fs.writeFile()覆盖该文件.
