A quick and easy service to generate up object and list resources with randomly generated data from chancejs.com
You know when you have a great idea for a web app, but you really don't want to spend a kazillion hours writing a server or mocking up data to demo the UI?
Chancify lets you quickly configure and run a server that serves up random objects or lists in the exact format you're dreaming of.
To generate random data in the shape you want, you just need to create a simple resource descriptor and drop it in the /descriptors directory, something like this:
// descriptors/simpleUser.js
function simpleUser(chance) {
return {
id: () => chance.guid(),
firstName: () => chance.first(),
lastName: () => chance.last(),
birthday: () => chance.birthday({ string: true }),
email: () => chance.email({ domain: 'example.com' }),
avatar: () => chance.avatar({ protocol: 'https' }),
}
}
module.exports = simpleUser% npm start
// fetch a single item
% curl http:https://localhost:7000/item/simpleUser
{"id":"46848381-512e-5a0e-b732-198bfb5af807","firstName":"Mario","lastName":"Fujiwara","birthday":"6/25/1954","email":"[email protected]","avatar":"https://www.gravatar.com/avatar/356a603e54119ad68d9390c9bc647b51"}
// fetch a list of them
% curl http:https://localhost:7000/list/simpleUser
[
{"id":"46848381-512e-5a0e-b732-198bfb5af807","firstName":"Mario","lastName":"Fujiwara","birthday":"6/25/1954","email":"[email protected]","avatar":"https://www.gravatar.com/avatar/b0f32c509992ec9ddb4e75ea4efd0fd2"},
{"id":"af4c4d41-952f-5196-a555-dfc7f4ff4a25","firstName":"Lily","lastName":"Horton","birthday":"3/6/1969","email":"[email protected]","avatar":"https://www.gravatar.com/avatar/e147f4025aa3125ad5456bb2e7abc709"},
{"id":"426aa2e0-fe2b-5f91-a644-e339b94b9efa","firstName":"Lois","lastName":"Aguilar","birthday":"9/9/1969","email":"[email protected]","avatar":"https://www.gravatar.com/avatar/9963d43b3251d705c663f871e5bf5944"},
{"id":"2806be78-159d-5f90-8533-d511442a2e65","firstName":"Terry","lastName":"Lombardi","birthday":"9/27/1971","email":"[email protected]","avatar":"https://www.gravatar.com/avatar/c12beea72d8daa04956cb69255e75353"},
{"id":"f6208c98-c34c-5788-bc1a-06f216a8f0a8","firstName":"Robert","lastName":"O'sullivan","birthday":"12/24/1983","email":"[email protected]","avatar":"https://www.gravatar.com/avatar/d96034285f177b97b5ea16a866ad5a47"},
{"id":"4a7c34a4-d09e-5538-90e3-dddcd046220d","firstName":"Nettie","lastName":"Kim","birthday":"1/16/1998","email":"[email protected]","avatar":"https://www.gravatar.com/avatar/a40e02ae422696964fbf8014100ae16f"},
{"id":"9f9154f8-5a8e-5179-8252-70d69efd032a","firstName":"Katherine","lastName":"Doyle","birthday":"9/20/1980","email":"[email protected]","avatar":"https://www.gravatar.com/avatar/268644621ad2351f1c241dbbf74f355d"},
{"id":"0a766b9d-6364-50de-abba-9a5870e64cb3","firstName":"Isaac","lastName":"Le GallGall","birthday":"11/11/1963","email":"[email protected]","avatar":"https://www.gravatar.com/avatar/6b55605cdc4063d34e5e45befcc2446b"},
{"id":"ed13bd0b-840f-5791-b1be-7d9cfa06aa37","firstName":"Larry","lastName":"Masuda","birthday":"4/21/1997","email":"[email protected]","avatar":"https://www.gravatar.com/avatar/56d9a4cc0abc088886d152e1aca08981"},
{"id":"235268e1-8c37-5a56-975e-fb4ae9fcd729","firstName":"Leo","lastName":"Pope","birthday":"1/17/1977","email":"[email protected]","avatar":"https://www.gravatar.com/avatar/e6b28a48540d1c1f5f11cc400663a2d3"}
]
The descriptors are really easy to build and deploy. Create a node file in the descriptors directory that exports a function. This function gets passed a chance object (more on this later) and returns a "template" of the resource you want to produce.
The fields of the template can be constants:
function myDescriptor(chance) {
return {
constantValue: 42
}
}Which would generate boring resources like:
{
constantValue: 42
}
Or the fields can be functions that return values. These functions can return anything you want, but because you are passed the chancejs object in the description function, you can use that to generate random stuff. For example:
function myDescriptor(chance) {
return {
name: () => {
return `${chance.first()} ${chance.last()}`
}
}
}Would generate objects like:
{ name: 'Leo Pope' }
You can even create nested objects:
function myNestedDescriptor(chance) {
return {
id: () => chance.guid()
name: {
first: () => chance.first(),
last: () => name.last(),
}
}
}There are two basic types of resources that you can request: an item resource and a list resource.
Lets imagine that you've produced a descriptor called my_crazy_object and put it in the /descriptors directory
To request a single random version of this object, you call the item endpoint:
% curl http:https://localhost:7000/item/my_crazy_object
To request a list of random objects, you call the list endpoint:
% curl http:https://localhost:7000/list/my_crazy_object
When requesting a list, you can specify how many are returned using the paging query parameters (more on this below). A small number of items at the start of the random data set is returned by default.
Chancify is intended to look like a really simple REST API, and as such it is intended to be stateless. How does that work when the values returned are random?
You will actually get the same result every time you call an endpoint, because the chance objects are constructed with a seed that guarantees consistent results.
In order to get different result, you pass a seed value as a URL query parameter. Using different seed values creates different results, but still allows the results to be stateless. For example:
// curl http:https://localhost:7000/item/simpleUser?seed=abcdefg
% curl -G http:https://localhost:7000/item/simpleUser --data-urlencode "seed=abcdefg"
{"id":"c4890d96-8f33-58ab-944a-c79c6e8b7feb","firstName":"Lottie","lastName":"Christensen","birthday":"1/14/1972","email":"[email protected]","avatar":"https://www.gravatar.com/avatar/1e9f4e12ff111fb392ea5c44faec2a95"}
You can page list resources by using the paging query parameters:
- max: The maximum total number of items in the list
- limit: The maximum number to return in a request (the page size)
- skip: The number of items to skip to the start of the page
For example:
// curl http:https://localhost:7000/list/simpleUser?max=100&skip=40&limit=20
% curl -G http:https://localhost:7000/list/simpleUser --data-urlencode "max=100" --data-urlencode "skip=40" --data-urlencode "limit=20"
If your paging reaches the end of the max items, then the list size returned may be less than the limit (it may even be zero)
Chancify is built on top of the very cool chancejs.com library, and you can visit the chancejs documentation to see all of the cool random things you can generate in your descriptors.
% git clone [email protected]:jaydsteele/chancify.git
% cd chancify
% npm start
To run in a docker container, you can:
% npm run docker:build
% npm run docker:run
Let me know if you use the library and find it useful. Feedback & suggestions are welcome and appreciated!
See LICENSE