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Show HN: Generate JSON mock data for testing/initial app development

jsongenerator.io

103 pointsNickba25 comments

Using real domains (like yahoo.com) for "fake" e-mail address is not a good practice. There are domains like example.com, example.net or example.org for such purposes (RFC 2606, RFC 6761).

That depends on what you’re trying to do. If you want it to be an obvious example, @example.com is great. If you want it to look like real data, such as in a demo or a screenshot, it’s not so great.

It’s a bit like saying that every demo user should be called John Doe or Jane Doe if they aren’t actual people.

"location": { "street": "853 Watsica Flat", "city": "North Biankaview", "state": "Wisconsin", "country": "India", "zip": "72621-2558", "coordinates": { "latitude": 6.5434, "longitude": -152.386 }

Could be a useful tool if this location data is coherent. State, City, Zip, Country and Lat/Lon are each of different places.

A friend and I had started a project similar to this some 6-7 years ago. We wanted to make all the generated data consistent so if, for example, you need data about German person it would return real city name, real (or at least plausible) street name, postal number, phone numbers both mobile and fixed with the proper country and operators code, email address using national domain, personal name was chosen out of plausible names for each country etc. etc. In the end it was so much work that we abandoned it :(

I have a similar project that generates random SQL rows, and yes, getting everything consistent is a huge pain. Mine generates city/country pairs that match, and has a limited set of countries that it will also generate matching phone numbers for. It ignores area/operator code differences.

Email addresses, it uses first.last@$RANDOM.com, no country-specific.

The other struggle I have is that to properly test a DB, you need millions of rows, not thousands. Mine does quite well up through a few million, but then starts struggling. I need to overhaul the generator functions to use threading. I hadn’t initially because I assumed the CPU would be too busy to context switch, but then I tried a smaller example and found I was wrong - massive speed up.

Yeah.. name, username, and 2 email addresses being different to one another is also irritating.. probably it's taxing for the brain if say testing with the user "brian.duncan" shows an exception in the UI, and then when scrolling through the logs one has to remember his email is "donna.tella@versace.it"...

     "name": {
        "first": "Shayna",
        "middle": "Quinn",
        "last": "Harris"
      },
      "username": "Burnice.Lehner27",
      "password": "o7DioxYA810KFBR",
      "emails": [
        "Sabryna_Roberts13@hotmail.com",
        "Stephen.Tremblay@gmail.com"
      ],

This is nice, but trivial to accomplish with the “faker” library available for most major programming languages - almost all reasonable web test frameworks will allow you to just make this json locally with the generated values, often with almost the exact same/extremely similar template syntax shown here.

There’s also json-schema-faker which is pretty cool.

https://github.com/json-schema-faker/json-schema-faker

Is there a generator for all the JSON generators out there?

https://json-generator.com/ https://www.objgen.com/json/local/design https://www.atatus.com/tools/json-generator https://www.site24x7.com/tools/json-generator.html

Not discounting the effort it takes to build a tool like this. It has, however, been done to death.

Is there a similar tool to generate API responses once you have an OpenAPI spec? Sort of a mock server, that can give out responses as per spec and occasionally induce errors. This will be helpful in decoupling frontend and backend during initial development.

I use https://stoplight.io/open-source/prism with x-faker properties in my OpenAPI specs to mock APIs with dynamic content.

Is it using https://fakerjs.dev/ ?

Not completely but for a good portion of it.

There was an interesting thread that did the rounds on HN a couple years back about using Faker in a related (but different) product.

https://news.ycombinator.com/item?id=27252066

Personally, I think your demo has a pretty neat / novel UX. I couldn't find a way to generate a large number of examples at once -- did I miss that somewhere?

So you should be able to use the repeat(numberOfTimes?) tag to generate an N number of examples. I believe I set the max now to 20.

But as long as the first index in an array is repeat(), anything in the second index will repeat N amount of times.

I've been using ChatGPT for this and it produces really good results, though of course the back-and-forth is a bit clunky. Would be great to build it into a more streamlined experience.

A friend of mine built a tool called Trex that you might find helpful, check it out here: https://github.com/automorphic-ai/trex

It's very consistent at generating templated data.

I assume Trex requires an internet connection the way it works?

Yes, using the API requires an internet connection but I believe you can also contact them (founders@automorphic.ai) to self-host on your own machine.

We provide this in https://github.com/outlines-dev/outlines.

Really great project! I think there are three small functions that would be great additions:

* IP's (V4, V6) * Enums (maybe something like enum('active', 'inactive', 'removed').) * Texts (like blog titles or description fields)

IPs and Enums added.

Is there an API for this? Much more useful to have a script that generates 10k mock objects and inserts into a database than generating in this web UI and copy/pasting :~)

Hoping to add that feature in. Not sure on the timeline.

nice little tool

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