Node.js sequentially running multiple childProcess.execFile processes from q all - node.js

Question

I am writing a program to batch print drawings. They need to be in a certain order ex. drawing A,B,C. The program plots the correct number of prints its just the order is random. I need the first in the array list to complete before next and so on.
startMe(newPaths)
.then(function(result){
})
function startMe(dwgPaths){
return q.all(buildCalls(dwgPaths));
}
var buildCalls = function(dwgPaths) {
var calls = [];
var scFiles = [tmpDir + "425011-fab.scr",tmpDir + "425011-pk.scr",tmpDir + "425011-sc.scr"];
for (var sc in scFiles){
for (var i in dwgPaths) {
calls.push(callAccoreConsole(dwgPaths[i],scFiles[sc]));
}
}
return calls;
};
function callAccoreConsole(dwgPath,scrFile){
var deferred = q.defer();
childProcess.execFile('C:/Program Files/Autodesk/AutoCAD 2015/accoreconsole.exe',['/i',dwgPath,'/s',scrFile], function(err, data) {
if(err)
deferred.resolve({success:false,reason: err});
deferred.resolve({success:true});
});
return deferred.promise;
}
The code below works the way I want. I print 2 files 3 copies each. File A using script 1,then File B using script 1. Then repeats for the other scripts. I have a total of 6 prints "three groups" A,B,A,B,A,B each with the appropriate script ran. With the code above I may get B,A,A,B,A,A.
callAccoreConsole(newPaths[0],scFiles2[0])
.then(function(result){
callAccoreConsole(newPaths[1],scFiles2[0])
.then(function(result){
callAccoreConsole(newPaths[0],scFiles2[1])
.then(function(result){
callAccoreConsole(newPaths[1],scFiles2[1])
.then(function(result){
callAccoreConsole(newPaths[0],scFiles2[2])
.then(function(result){
callAccoreConsole(newPaths[1],scFiles2[2])
.then(function(result){
})
})
})
})
})
});
I have been struggling with this for a while. I found the code below and got it to work for my application, But it doesn't seem the most efficient way to be written. If any one has a more compact way let me know please.Thanks
var itemsToProcess = [];
for (var sc in scFiles){
for (var i in newPaths) {
itemsToProcess.push( {file:newPaths[i],script:scFiles[sc]});
}
}
function getDeferredResult(a) {
return (function (items) {
var deferred;
if (items.length === 0) {
return q.resolve(true);
}
deferred = q.defer();
var payload = {
file:items[0].file,
script:items[0].script
};
callAccoreConsole2(payload)
.then(function(result){
deferred.resolve(items.splice(1));
});
return deferred.promise.then(getDeferredResult);
}(a));
}
q.resolve(itemsToProcess)
.then(getDeferredResult)
.then(function(result){
return res.send({success:true});
})

Answer 1

As you are constructing your array of promises you are simultaneously invoking the execFile method.
function callAccoreConsole(dwgPath,scrFile){
var deferred = q.defer();
childProcess.execFile('C:/Program Files/Autodesk/AutoCAD 2015/accoreconsole.exe',['/i',dwgPath,'/s',scrFile], function(err, data) {
if(err)
deferred.resolve({success:false,reason: err});
deferred.resolve({success:true});
});
return deferred.promise;
}
So, instead using callAccoreConsole to run the process and return a deffered, you need something that calls that method eventually -
calls.push(q.fcall(callAccoreConsole, dwgPaths[i],scFiles[sc]));
I haven't tried this specifically, but the gist is that you are calling your method at the same time you are creating the deferred for it.