flatjson

Overview

flatjson converts JSON files to a "flat" representation with one value per line. For example, given the input:

{
  "menu": {
    "id": "file",
    "value": "File",
    "popup": {
      "menuitem": [
        {
          "value": "New",
          "onclick": "CreateNewDoc()"
        },
        {
          "value": "Open",
          "onclick": "OpenDoc()"
        },
        {
          "value": "Close",
          "onclick": "CloseDoc()"
        }
      ]
    }
  }
}

flatjson outputs:

root = {};
root.menu = {};
root.menu.id = "file";
root.menu.popup = {};
root.menu.popup.menuitem = [];
root.menu.popup.menuitem[0] = {};
root.menu.popup.menuitem[0].onclick = "CreateNewDoc()";
root.menu.popup.menuitem[0].value = "New";
root.menu.popup.menuitem[1] = {};
root.menu.popup.menuitem[1].onclick = "OpenDoc()";
root.menu.popup.menuitem[1].value = "Open";
root.menu.popup.menuitem[2] = {};
root.menu.popup.menuitem[2].onclick = "CloseDoc()";
root.menu.popup.menuitem[2].value = "Close";
root.menu.value = "File";

This format, although verbose, makes it much easier to see the nesting of values. It also happens to be valid JavaScript that can be used to recreate the original JSON object.

This "flat" format is very handy for visualizing diffs. For example, comparing the above JSON object with a second JSON object:

{
  "menu": {
    "id": "file",
    "disabled": true,
    "value": "File menu",
    "popup": {
      "menuitem": [
        {
          "value": "New",
          "onclick": "CreateNewDoc()"
        },
        {
          "value": "Open",
          "onclick": "OpenDoc()"
        }
      ]
    }
  }
}

yields the diff:

--- testdata/a.json
+++ testdata/b.json
@@ -1,5 +1,6 @@
 root = {};
 root.menu = {};
+root.menu.disabled = true;
 root.menu.id = "file";
 root.menu.popup = {};
 root.menu.popup.menuitem = [];
@@ -9,8 +10,5 @@
 root.menu.popup.menuitem[1] = {};
 root.menu.popup.menuitem[1].onclick = "OpenDoc()";
 root.menu.popup.menuitem[1].value = "Open";
-root.menu.popup.menuitem[2] = {};
-root.menu.popup.menuitem[2].onclick = "CloseDoc()";
-root.menu.popup.menuitem[2].value = "Close";
-root.menu.value = "File";
+root.menu.value = "File menu";

Installation

go install github.com/twpayne/flatjson/cmd/flatjson

Converting JSON to flat JSON

To convert a JSON file to flat JSON, specify it on the command line, for example:

flatjson vendor/vendor.json

If no filenames are specified, flatjson will read JSON from the standard input.

Generating flat JSON from JSON

To reverse the transformation, i.e. to convert flat JSON to JSON, specify the -reverse option.

Generated a unified diff

To generate a unified diff between two JSON files, specify the -diff option and the filenames on the command line, for example:

flatjson -diff ./testdata/a.json ./testdata/b.json

An additional -context option specifies how many lines of context to show. The default is three.

License

MIT