Comparing JSON files

[Gitoffthelawn]

I thought I posted a discussion item about this before, but I don't see it. Please accept my apologies if this is a duplicate.

I want to compare JSON files. To try to accomplish this, I first use jq to sort the JSON files by the correct array elements and to pretty print the JSON.

I then try to use WinMerge to compare two JSON files pre-processed in this manner. Unfortunately, the result isn't really usable. I haven't been able to find a way to get WinMerge to recognize JSON arrays, which is needed for meaningful results.

Is there any way to use WinMerge to compare JSON files?

If not, is there a similar offline tool to compare JSON files?

BTW, I tried several different online JSON comparison tools, and all had poor results and were staggeringly slow (1+ hour to compare two 1 MB JSON files).

Thanks in advance.

[sdottaka]

I haven't tried it, but there seem to be several tools for comparing JSON-like tree structures at the following URLs

https://difftastic.wilfred.me.uk/tree_diffing.html

By the way, what results were you expecting and what results did you get with WinMerge?

Note that WinMerge has a PrettifyJSON plugin that uses jq to format a JSON file, and a QueryJSON plugin that uses jq to retrieve part of a JSON file.

[Gitoffthelawn]

Thanks. I've taken a look at most of the tools mentioned on that page, and I haven't found one that gives context like WinMerge. One reason I love WinMerge (as opposed to diff or diff-like tools) is that you can see the context of all changes in WinMerge.

Here's a good example of JSON that WinMerge struggles to compare:
https://costplusdrugs.com/medications/

The JSON begins at the string {"props within the page's source code.

If you download the source code for that page, and then delete everything before {"props, you should have valid JSON.

The content of that page currently changes about every day, so if you wait a day and download the source code again (and strip everything before {"props), you'll have 2 JSON files to compare.

Once you have JSON files from 2 different days from that site, try comparing them with WinMerge. The JSON contains an array of medications, and you'll notice that the WinMerge output is not very useful. The reason is because WinMerge doesn't understand that each array item in JSON file 1 needs to be compared to the matching array item in JSON file 2.

If you're interested, here is the jq command I wrote to sort the JSON by medication name:
jq ".props.pageProps.categories[].medications|=sort_by(.name)" "day1.json" >"day1_sorted.json"

Even with performing this pre-WinMerge sorting by medication name, WinMerge's output does not improve enough to make the output useful.

I would love to be able to compare JSON files in a meaningful way within WinMerge, or at least find an open source tool that displays context (like WinMerge) to perform this task.

[elisimpson]

Came here to say the same thing. Winmerge seems to want to start/end matches inside the obj rather than at the beginning of the obj. So Winmerge matches something like this:

  name1:value1,
  name2:value2
},
{

instead of:

{
  name1:value1,
  name2:value2
},

[endolith]

Is there a "prediffer" for formatting the json files so that it can compare lines?

[sdottaka]

There is no prediffer plugin for json files. Wouldn't the PrettifyJSON or QueryJSON plugins solve your problem?

[endolith]

@sdottaka I don't know, how do you use them?

[sdottaka]

For usage examples of the PrettifyJSON unpacker plugin and the QueryJSON unpacker plugin, please refer to the following:

#2344 (comment)
#2163 (comment)

[endolith]

To use it, you just select PrettifyJSON in this unpacker drop-down: