adaka
v0.1.0
Published
High-precision state management using MongoDB query language.
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Readme
adaka
High-precision state management using MongoDB query language.
Install
npm i adaka
Features
- Manage state as a single document modifiable only through the store API.
- Update state using MongoDB update query language.
- Use selectors to precisely observe specific data in state and subscribe to be notified only when they change.
- Subscribers are notified with a frozen immutable object.
- Restrict state notifications with conditions expressed as queries.
- Automatically unsubscribes a listener if it throws an exception.
- Performs value equality using deep equal.
- React integration via react-adaka.
Usage
Import the createStore
function to get started.
import { createStore } from "adaka";
Create store and select some data.
type Person = { name: string; age: number; children?: string[] };
const store = createStore<Person>({
name: "John",
age: 30,
children: ["Luke"]
});
// create a selector
const selector = store.select<{ name: string }>({ name: 1 });
// subcriber runs whenever name changes.
const unsubscribe = selector.subscribe(view => {
console.log("->", view);
});
// first update
store.update({ $set: { name: "Amoah" } }); //output: '-> {name:"Amoah"}'
// can also use selector.getState() to obtain the value directly.
console.log(selector.getState()); // {name: "Amoah"}
// second update
store.update({ $set: { name: "Donkor" } }); //output: '-> {name:"Donkor"}'
// third update on different part of the state. subscriber is not notified.
store.update({ $push: { children: "Ama" } }); // no output
// remove subscriber by calling return method.
unsubscribe();
// subscriber no longer runs
store.update({ $set: { name: "Odame" } }); // no output
Select data only on condition
A selector may use a condition to restrict when listeners are notified. When a condition is used listeners are notified
only once for when the condition is false with a return value of undefined
. Further updates that do not meet the condition
do not trigger anymore notifications. On the other hand, any update that meets the condition triggers a notification.
// store object.
// ------------
// {
// name: "John",
// age: 30,
// children: ["Luke"]
// }
// second child if person under 30.
const selector = store.select<{ secondChild: string }>({
secondChild: "$children.1"
}, {age: {$lt: 30}});
selector.subscribe(data => {
console.log("->", data);
});
selector.getState() // undefined
store.update({$set: {age: 25}})
// no second child yet.
selector.getState() // {}
store.update({ $push: { children: "Adrian"} })
selector.getState() // { secondChild: 'Adrian' }. listeners notified.
store.update({ $set: { age: 35 } })
selector.getState() // undefined. listeners notified.
store.update({ $set: { age: 40 } })
selector.getState() // undefined. no notifications because condition is false.
React Integration
The react-adaka and React >=18.2.0
libraries are required to use this integration.
import { createStore, createSelectorHook } from "react-adaka"
// first create your store
const store = createStore({
status: "error",
errors: [
{ type:"api", message: "unknown error" }
],
});
// create a selector hook some where in global scope. need one per store.
const useSelector = createSelectorHook(store)
// use the hook inside your React component.
function ShowErrorTypes() {
// select the types of errors only when the status is in "error".
const { errorTypes } = useSelector({ errorTypes: "$errors.type" }, { status: "error"})
return errorTypes ? <div>Issues found: {errorTypes.join("\n")} </div> : <div/>
}
MongoDB Query and Update Support
This package uses the mingo library for MongoDB query language support and loads only the basic supported query
, projection
, expression
, and all update
operators by default. Refer to the readme page for more information.
The mingo
libray is added as a peer dependency to enable users to select only required operators using the context
option so that tree-shaking can work effectively. Basic mingo
operators are loaded into the global context by default.
TODO
- Support schema validation
License
MIT