等待数组中每个项的承诺

我正在节点中使用ssh2 sftp客户机下载一系列文件。下载完这些文件后,我需要检查每个文件是否是csv文件,然后检查我的数据库以查看它是否以前导入过。

我用的是承诺,在排序上有困难。我想经过几个小时的研究,我已经接近尾声了,但还不能完全理解。

代码如下:

const isFileCSV = (filename) => {

    return new Promise( (resolve, reject) => {
        if (filename.endsWith('.csv')) {
            result = 'true';
            resolve(result);
        } else {
            result = 'false';
            resolve(result);
        }
    });
}

const wasFileImported = (filename) => {     
    // Return a new promise
    return new Promise( (resolve, reject) => {
        // Core function
        con.query(`CALL wasFileImported('${filename}')`, (err, results) => {
            console.log('02 Checking if file was previously imported.');    
            if (err) {
                logEntry('error', `Error searching database: ${err}`);
                reject(Error('false'));
            } else {
                result = results[0][0]['importCheck'];
                resolve(result);
            }
        })
    });
}

const importFile = (file) => {
    isFileCSV(file).then((result) => {
        console.log(`01a File ${file} ends with csv? ${result}`);
        result = result.toLowerCase();
        return result;
    }).then((result) => {
        if (result === 'false') {
            console.log(`01b ${result} = Not csv, log it and skip to next.`);
            return;
        } else if (result === 'true') {
            console.log(`01b ${result} = It is csv, go to next step`);
            return result;
        }
    }).then((result) => {
        wasFileImported('file').then((result) => {
            console.log('03 checked import, result: ', result);
            return result.toLowerCase();
        }).then((result) => {
            switch(result) {
                case 'false':
                    console.log('04a download file and log it');
                    break;
                case 'true':
                    console.log('04b skip it and log the skip');
                    break;
                default:
                    console.log('04c unknown error, log the skip');                         
            }           
        })              
    })              
}

logEntry('info', `attempting to connnect to ${config.destination.host}`);
console.log('00 start');

sftp.connect(crmConfig).then(() => {
    logEntry('info', `connected to ${config.destination.host}`);
    return sftp.list(ordersUrl);
}).then((data) => {
    fileList = [];
    Object.entries(data).forEach(([key, val]) => {
        fileList.push(val['name']);
    });
    return fileList;
}).then((fileList) => {
    let promises = [];

    fileList.forEach((file) => {
        promises.push(importFile(file));
    });

    Promise.all(promises).then(function(results) {
        console.log('Done');
    }).catch(function(err) {
        console.log('Error');
    });
});

我想看到的是:

00 start
01a File daily.csv ends with csv? true
01b true = It is csv, go to next step
02 Checking if file was previously imported.
03 checked import, result:  FALSE
04a download file and log it
01a File daily072418.csv ends with csv? true
01b true = It is csv, go to next step
02 Checking if file was previously imported.
03 checked import, result:  FALSE
04a download file and log it
01a File test.csw ends with csv? false
01b false = Not csv, log it and skip to next.
02 Checking if file was previously imported.
03 checked import, result:  FALSE
04a download file and log it
Done

我真正得到的是:

00 start
01a File daily.csv ends with csv? true
01a File daily072418.csv ends with csv? true
01a File test.csw ends with csv? false
01b true = It is csv, go to next step
01b true = It is csv, go to next step
01b false = Not csv, log it and skip to next.
Done
02 Checking if file was previously imported.
03 checked import, result:  FALSE
04a download file and log it
02 Checking if file was previously imported.
03 checked import, result:  FALSE
04a download file and log it
02 Checking if file was previously imported.
03 checked import, result:  FALSE
04a download file and log it

早期版本没有使用promise.all,但仍然生成相同的结果。我还尝试改变返回wasfileimported和isfilecsv的决心,但是我只得到“00 start”和“done”,中间没有执行。

很明显,我并没有正确地遍历数组以获得我想要的结果。要做到这一点,最好的方法是什么?所有事情都是按顺序完成的?

编辑 对于任何其他需要它的人,这是最后的工作代码,感谢@jordan peterson和@spakmad:

const isFileCSV = (filename) => {
    return new Promise( (resolve, reject) => {
        if (filename.endsWith('.csv')) {
            result = 'true';
            resolve(result);
        } else {
            result = 'false';
            resolve(result);
        }
    });
}

const wasFileImported = (filename) => {     
    // Return a new promise
    return new Promise( (resolve, reject) => {
        // Core function
        con.query(`CALL wasFileImported('${filename}')`, (err, results) => {
            console.log('02 Checking if file was previously imported.');    
            if (err) {
                logEntry('error', `Error searching database: ${err}`);
                reject(Error('false'));
            } else {
                result = results[0][0]['importCheck'];
                resolve(result);
            }
        })
    });
}

const importFile = (file) => {
    return isFileCSV(file).then((result) => {
        console.log(`01a File ${file} ends with csv? ${result}`);
        result = result.toLowerCase();
        return result;
    }).then((result) => {
        if (result === 'false') {
            console.log(`01b ${result} = Not csv, log it and skip to next.`);
            return;
        } else if (result === 'true') {
            console.log(`01b ${result} = It is csv, go to next step`);
            return result;
        }
    }).then((result) => {
        return wasFileImported('file').then((result) => {
            console.log('03 checked import, result: ', result);
            return result.toLowerCase();
        }).then((result) => {
            switch(result) {
                case 'false':
                    console.log('04a download file and log it');
                    break;
                case 'true':
                    console.log('04b skip it and log the skip');
                    break;
                default:
                    console.log('04c unknown error, log the skip');                         
            }           
        })              
    })              
}

console.log('00 start');

sftp.connect(crmConfig).then(() => {
    logEntry('info', `connected to ${config.destination.host}`);
    return sftp.list(ordersUrl);
}).then((data) => {
    fileList = [];
    Object.entries(data).forEach(([key, val]) => {
        fileList.push(val['name']);
    });
    return fileList;
}).then((fileList) => {
    let promiseChain = Promise.resolve()

    fileList.forEach((file) => {
        promiseChain = promiseChain.then(() => {
            return importFile(file)
        })
    })
});