task not waiting for dependency to finish

Shouldn’t this work?

var gulp = require('gulp');
var del = require('del');

...

gulp.task('clean', function(callback) {
  del([ site.build + '/**' ], callback);
});

gulp.task('build', [ 'clean' ], function() {
  return gulp.start('html', 'less', 'js', 'png', 'jpg');
});

gulp.task('deploy', [ 'build' ], function() {
 ...
});

Unfortunately deploy runs before build finished.

gulp.task('clean', function(callback) {
  del([ site.build + '/**' ], callback);
});

gulp.task('build', [ 'clean', 'html', 'less', 'js', 'png', 'jpg' ], function() {
});

gulp.task('deploy', [ 'build' ], function() {
 ...
});

The above does not work either as clean is run in parallel.

So what’s the suggested way of doing this?

[thomashigginbotham]

Even with run-sequence, I was having the same problem. Here’s how I worked around it:

gulp.task('build', function(callback) {
  gulp.src('abc.xyz')
    .pipe(someTask())
    .pipe(gulp.dest('dist'))
    .on('end', callback);
});

gulp.task('deploy', [ 'build' ], function() {
  /* The .on('end', callback) above ensures that the "build" task has fully completed. It's
     now safe to use "dist/abc.xyz". */
});

[leonliao]

Met same issue here. Let’s say there are 2 tasks, First and Second. Second runs after First. The First task generates some files, which are to be read by the Second task. Using dependency doesn’t make sure the Second task can find the files generated.

I have to explicitly using the done callback on the pipeline to let Second only starts after First truly done.

//This approach works!
gulp.task('First', function(done)) {
   var subFolders = fs.readdirSync(somefolder)...
   var tasksForFolders = subFolders.map(function(folder) {
       return gulp.src('folder/**/*').sthtogeneratefiles();
   });
   tasksForFolders[tasksForFolders.length-1].on('end',done);
   return tasksForFolders;
}

gulp.task('Second', ['First'],function() {
    return gulp.src('generatedfolders/**/*').doth();
}

Without the done trick, the Second never finds the files generated by First. Below shows what I tried, the Second task can find the files generated by calling gulp First by hand, and then calling gulp Second subsequently.

//This is the WRONG approach, just for demonstration!!
gulp.task('First', function()) {
   var subFolders = fs.readdirSync(somefolder)...
   var tasksForFolders = subFolders.map(function(folder) {
       return gulp.src('folder/**/*').sthtogeneratefiles();
   });
   return tasksForFolders;
}

gulp.task('Second', function() {
    return gulp.src('generatedfolders/**/*').doth();
}