I'm new to javascript also node.js environment. It's hard for me to use the call back. Because when I have a lot of procedure linked together, it's hard to write and it will becomes very nasty.
So, after I google for the answer, I found the async tool, but it still run like that it can execute the codes block by block using call back. for example, f1 -> f2 -> f3 ...
however, we always has a delay for the server and my computer. then If I do some thing like create buckets, then print how many I got. It will print out the original amount of buckets not after I add one. Same situation like delete bucket .... can some god help me
thanks...
function bucketSerialTesting(s3)
{
async.series([
function f1(callback)
{
settingBucket ('testjsbucket2',s3);
callback('1');
}
,
function f2(callback)
{
settingBucket('testjsbucket3', s3);
callback('2');
}
,
function f3(callback)
{
listBucket(s3);
callback('3');
}
,
function f4(callback)
{
deleteBucket('testjsbucket2', s3);
callback('4');
}
,
function f5(callback)
{
deleteBucket('testjsbucket3', s3);
callback('5');
}
,
function f6(callback)
{
listBucket(s3);
callback('6');
},
],
function(err, results){
console.log(results);
});
}
function settingBucket (bucketName, s3){
var s3 = new AWS.S3();
var params = {
Bucket: bucketName, /* required */
};
s3.createBucket(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else console.log(data); // successful response
}).on('success',function(response)
//put bucket cors for browsers javascript testing
{
var params = {
Bucket: bucketName, /* required */
CORSConfiguration: {
CORSRules: [
{
AllowedHeaders: ['*',],
AllowedMethods: ['GET','PUT','DELETE','POST'],
AllowedOrigins: ['*','null'],
ExposeHeaders: ['ETag',],
},
]
},
};
s3.putBucketCors(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else {
console.log(data);
console.log('put bucketcors succeed');
}
});
}).send();
}
function listBucket(s3)
{
s3.listBuckets(function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else {
console.log(data);
console.log('we have '+data.Buckets.length.toString()+' buckets');
for (var i = data.Buckets.length - 1; i >= 0; i--) {
console.log(data.Buckets[i].Name);
};
} // successful response
});
}
function deleteBucket(bucketName, s3){
var params = {
Bucket: bucketName, /* required */
};
s3.listObjectVersions(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else{
console.log(data);
params = {Bucket: bucketName};
params.Delete = {};
params.Delete.Objects = [];
console.log(data.Versions.length);
for(j = 0; j < data.Versions.length;++j)
{
params.Delete.Objects.push({Key: data.Versions[j].Key,
VersionId: data.Versions[j].VersionId
});
}
for(j = 0; j < data.DeleteMarkers.length;++j)
{
params.Delete.Objects.push({Key: data.DeleteMarkers[j].Key,
VersionId: data.DeleteMarkers[j].VersionId
});
}
s3.deleteObjects(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else {
console.log(data);
}
params = {Bucket: bucketName};
s3.deleteBucket(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else console.log(data); // successful response
});
});
}
});
}
function bucketSerialTesting(s3)
{
Q.fcall(function f1()
{
return settingBucket ('testjsbucket20',s3);
})
.then(function f2()
{
return settingBucket('testjsbucket30', s3);
}
)
.then(function f3()
{
return listBucket(s3);
}
)
.then(function f4()
{
return deleteBucket('testjsbucket20', s3);
}
)
.then(function f4()
{
return deleteBucket('testjsbucket30', s3);
}
)
.then(function f4()
{
return listBucket(s3);
}
)
.done();
}
function settingBucket (bucketName, s3){
var deferred = Q.defer();
var s3 = new AWS.S3();
var params = {
Bucket: bucketName, /* required */
};
s3.createBucket(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else console.log(data); // successful response
}).on('success',function(response)
//put bucket cors for browsers javascript testing
{
var params = {
Bucket: bucketName, /* required */
CORSConfiguration: {
CORSRules: [
{
AllowedHeaders: ['*',],
AllowedMethods: ['GET','PUT','DELETE','POST'],
AllowedOrigins: ['*','null'],
ExposeHeaders: ['ETag',],
},
]
},
};
s3.putBucketCors(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else {
console.log(data);
console.log('put bucketcors succeed');
deferred.resolve(data);
}
});
}).send();
return deferred.promise;
}
function listBucket(s3)
{
var deferred = Q.defer();
s3.listBuckets(function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else {
console.log(data);
console.log('we have '+data.Buckets.length.toString()+' buckets');
for (var i = data.Buckets.length - 1; i >= 0; i--) {
console.log(data.Buckets[i].Name);
};
deferred.resolve(data);
} // successful response
});
return deferred.promise;
}
function deleteBucket(bucketName, s3){
var deferred = Q.defer();
var params = {
Bucket: bucketName, /* required */
};
s3.listObjectVersions(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else{
console.log(data);
params = {Bucket: bucketName};
params.Delete = {};
params.Delete.Objects = [];
// console.log(data.Versions.length);
for(j = 0; j < data.Versions.length;++j)
{
params.Delete.Objects.push({Key: data.Versions[j].Key,
VersionId: data.Versions[j].VersionId
});
}
for(j = 0; j < data.DeleteMarkers.length;++j)
{
params.Delete.Objects.push({Key: data.DeleteMarkers[j].Key,
VersionId: data.DeleteMarkers[j].VersionId
});
}
s3.deleteObjects(params, function(err, data) {
if (err) {
console.log(err, err.stack);
console.log('or has no objects');// an error occurred
}
else {
console.log(data);
}
params = {Bucket: bucketName};
s3.deleteBucket(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else {
console.log(data);
deferred.resolve(data);
}
});
});
}
});
return deferred.promise;
}
One option is Q promises which really helps to unwind the callback hell and flatten your code out a bit.
https://github.com/kriskowal/q
The defer, resolve/reject pattern would work well for you.
Here's an example that flattens out async work. It prints a file hello.txt (that exists), waits a second, errors on a file that doesn't exist, jumps to the fail handler and then runs the finally.
var Q = require('q');
var fs = require('fs');
var path = require('path');
// a promise just defers execution of success or failure - must return the promise. notice how it calls resolve in the callback of the async function.
var wait = function(ms) {
var defer = Q.defer();
console.log('waiting ' + ms + ' ms');
setTimeout(function() {
defer.resolve();
}, ms);
return defer.promise;
}
// you can wrap a node callback function with Q.defer and call reject or resolve
var getFileContents = function(path) {
var defer = Q.defer();
fs.readFile(path, function(err, data) {
if (err) {
defer.reject(err);
}
else {
// can't pass multiple args back - it returns one obj
defer.resolve({ path: path, data: data });
}
});
return defer.promise;
}
var ms = 1000;
var printFile = function(filePath) {
// even function wrapping up work returns a promise so it can be
// connected with another outer sequence of work
return wait(ms)
.then(function() {
console.log(new Date().toString());
})
.then(function() {
// if you call async that returns promise, you must return it
return getFileContents(filePath);
})
// the resolve data from previous promise is passed as input to next then
.then(function(contents) {
console.log(contents.path + ':');
console.log(contents.data.toString());
})
}
// sometimes you need to just return a no op based on a conditional check etc...
var noOpPromise = function() {
console.log('no op');
return Q(null);
}
printFile(path.join(__dirname, 'hello.txt'))
.then(function() {
// throw new Error('throwing will jump to fail');
return wait(1000);
})
.then(function() {
return printFile(path.join(__dirname, 'noexist.txt'));
})
.then(function() {
console.log('should never get here');
})
// can also use .catch
.fail(function(err) {
console.error('Error: ' + err.message);
})
.fin(function() {
console.log('done with work');
})
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