Not works if source and destination files is same about gulp-changed

[plankguy]

As a work-around, i'm writing to a cache folder:

gulp.task('imagemin', function() {
    gulp.src( './images/**/*' )
        .pipe( plugins.changed( './.cache/imagemin' ) ) // check cache
        .pipe( plugins.imagemin( settings.imagemin ) )
        .pipe( gulp.dest( './.cache/imagemin' ) ) // write to cache
        .pipe( gulp.dest( './images' ) );
});

There's likely a more elegant solution, but this works for now!

[michaek]

I think that's by design. The library works by comparing the mtime of two files to detect changes, and if it's comparing the mtime of a file against itself, it will always appear to be unchanged.

[LZ-TimHunold]

It would be very useful to do this. For me, I have a staging server that gets files pushed to it and I wanted to add a task that will run things like uglify and csso to take the file and optimize itself.

[michaek]

Without a different destination, what is your proposal for being able to determine if the file is changed or unchanged?

[plankguy]

+1 for this.

I'm using imagemin, and i'd like to only compress files that are changed, but do so in the same 'images' directory, rather than having to write to another directory.

As for implementation - write to a cache file that tracks the changes w/ mtime, then check the cache, rather than the src file as reference for changed/unchanged.

[red2678]

+1 for this

[samIntegrateur]

+1

[michaek]

It seems like what you're looking for is just a custom hasChanged function. In the cases you're describing, you want to compare the file source file not against its destination (which is the same) but against the time of the last run. If the file is newer than the last run, return true from your hasChanged implementation, and that file will proceed through the stream for processing. I am almost certain this case isn't going to find its way into the library, and it's straightforward to make your own hasChanged.

[marcobiedermann]

I am having the same problem. My idea is to create a hash database (plain json file) for all files and write a custom comparison function to lookup if hash already exists in db, if so skip the process.
It would be great to have such a feature build in. 👍

[svivian]

Not working for me either. I'm using with with gulp-imagemin like this:

return gulp.src(dir + '/**')
	.pipe(imagemin(
		[imagemin.optipng(), imagemin.jpegtran(), imagemin.gifsicle()]
	))
	.pipe(changed(dir))
	.pipe(gulp.dest(dir));

It says gulp-imagemin: Minified 1 image (saved 288 B - 36.9%) but the file is not saved.

Maybe I'm misunderstanding something, but shouldn't it pick up that the files in the stream have been modified compared to the files on disk?

[weslley-campos]

Not working for me either. I'm using with with gulp-imagemin like this:

return gulp.src(dir + '/**')
	.pipe(imagemin(
		[imagemin.optipng(), imagemin.jpegtran(), imagemin.gifsicle()]
	))
	.pipe(changed(dir))
	.pipe(gulp.dest(dir));

It says gulp-imagemin: Minified 1 image (saved 288 B - 36.9%) but the file is not saved.

Maybe I'm misunderstanding something, but shouldn't it pick up that the files in the stream have been modified compared to the files on disk?

I am like the same problem, for this plugin to work the source needs to be different from the destination.
But I need them to be the same.

[sindresorhus]

Like @michaek said, this is by design. I would be happy to add more built-in comparator functions if someone can come up with a clever design though.