Is it possible to use Automator/Applescript to generate a JSON file by the reading contents of a folder?

Question

I would like to know if it's possible to automate the creation of a JSON file by using Automator and Applescript.

Scenario: I have folders of images, and I have been creating JSON files that list the various properties about the images: num, filename, percent, category.

num = each file in the folder is assigned a number, 1 to infinity
filename = name of the image file in the folder (without the extension)
percent = the image's height divided by the image's width
category = the name of the folder that the images are located

My JSON code is formatted like:

 {
   "num": 1,
   "filename": "image-name",
   "percent": 66.67,
   "category": "nature-images"
 }

Would it be possible to come up with a script that could look at the contents of a folder and create a JSON file with the above properties per image? I'm brand new to Applescript (or any form of automation code) so any help to put me in the right direction would be great.

Answer 1

I would suggest doing that with a bash shell script, which you can call from Applescript using:

do shell script "SCRIPTNAME"

So, to see how my approach works, you could run the Apple-supplied sips program like this:

sips -g all *.png

Sample Output

/Users/mark/StackOverflow/1010.png
  pixelWidth: 100
  pixelHeight: 100
  typeIdentifier: public.png
  format: png
  formatOptions: default
  dpiWidth: 72.000
  dpiHeight: 72.000
  samplesPerPixel: 4
  bitsPerSample: 2
  hasAlpha: yes
  space: RGB
  profile: sRGB IEC61966-2.1
/Users/mark/StackOverflow/1020.png
  pixelWidth: 100
  pixelHeight: 100
  typeIdentifier: public.png
  format: png
  formatOptions: default
  dpiWidth: 72.000
  dpiHeight: 72.000
  samplesPerPixel: 4
  bitsPerSample: 2
  hasAlpha: yes
  space: RGB
  profile: sRGB IEC61966-2.1
/Users/mark/StackOverflow/2.png
  pixelWidth: 640
  pixelHeight: 480
  ...
  ...

So, I propose parsing this with some awk which basically looks for patterns and does things when it finds them. Save this as $HOME/parser.sh:

#!/bin/bash

# Do specified directory, or HOME if none specified
cd "$1"

# Generate a list of all image filenames and heights and widths with "sips", discarding errors
sips -g all * 2> /dev/null | awk -v category="$(pwd)" '
   BEGIN          {serial = 1}           # allocate serial number
   /^[^ ]/        {filename = $0}        # pick up path if line does not start with space
   /pixelWidth:/  {width = $NF}          # pick up last field as width
   /pixelHeight:/ {
       height  = $NF                     # pick up last field as height
       sub(".*/", "", filename)          # extract filename from full path
       aspect = 100*height/width         # calculate aspect ratio
       printf("{\n")
       printf("   \"num\": %d,\n", serial)
       printf("   \"filename\": \"%s\",\n", filename)
       printf("   \"percent\": %f,\n", aspect)
       printf("   \"category\": \"%s\"\n",category)
       printf("}\n")
       serial += 1
   }'

Then make it executable (just necessary once) with:

chmod +x $HOME/parser.sh

Then you can run it with a command like this to check all images on your Desktop:

$HOME/parser.sh /Users/YOU/Desktop

And run it from Applescript with something like:

do shell script parser.sh "SomeDirectory"

The output is like this:

{
   "num": 1,
   "filename": "1010.png",
   "percent": 100.000000,
   "category": "/Users/mark/StackOverflow"
}
{
   "num": 2,
   "filename": "1020.png",
   "percent": 100.000000,
   "category": "/Users/mark/StackOverflow"
}
{
   "num": 3,
   "filename": "2.png",
   "percent": 75.000000,
   "category": "/Users/mark/StackOverflow"
}

---

If you want the output in a file called assets.json on your Desktop, use:

$HOME/parser.sh SOMEDIRECTORY > $HOME/Desktop/assets.json

---

If you want square brackets at the start and end of your output, change as follows:

BEGIN  { serial = 1; print "[" }
END    { print "]" } 

---

If you are unfamiliar with writing shell scripts, and you use TextEdit, be sure not to make an RTF document, so use the TextEdit Format menu to do Format->Make Plain Text.