ManjitShortcut / Flutter_Provider

Flutter Provider

1. Flutter provider is basically used to pass the data to child class widget and also notify to when vlue changes.

How to use Flutter provider

Just consider a product app and wen need to pass all product list through out the app and modify specifice ui element then you need to render whole ui There is two method that is 1.create a constructor and passthrouhg to child object then next child object. 2. Create a Provider and Pass to next class then next will next to next child class. and widget.

1. Add dependancy to your project provider: ^3.0.0
2. Add provider to your parent widget.

Syntax

 ChangeNotifierProvider(
      create: (ctx) =>
          ProductList class(), // when you are using creating new object instance the user provider.create
      child: ParentClass // allocation

Read provider Value from child widget

Read proivide value from child calss using

 final ProductList productList = Provider.of<ProductList>(context);  // where product list pass through provider
 if you want to donot notify the object then user 
 final ProductList productList = Provider.of<ProductList>(context,listen: false);  

Consumer

Consumner also one type of widget where it read the value of the provider.The best ting of the consumer is that it will render whole wifget again .It will render specific element.

Syntax

 ```
 Consumer<Dynamic> (
 builder:(ctx, DynamicObject, child) =>Your wudget where Dynamic is the specific object that pass through from parent class to child calss.
 # Example
 Consumer<Product>(
        builder: (ctx, product, child) => IconButton(
            icon: Icon(
              Icons.favorite,
              color: item.isFavorite ? Colors.red : Colors.black,
            ),
            onPressed: () {
              item.setFavorite();
            }),
 ```

How Provider Lister if there is any chages to object

Syntax

Class Product with ChangeNotifier {
void addObject(){
notifyListeners(); All the child class will notify when the add method call
}

What is the difference between Provider.Value and Provider.Create or when user provider value and Provider

if the object already allocated then use ChangeNotifierProvider.value or if you want to use allocted object at the create time then use ChageNotifierProvider(create:(cxt)=> allocated object

Syntax

  ```
  ChangeNotifierProvider(create:(ctx) => AllocatedObject();
  ChangeNotifierProvider.Value(value: ReferenceOf the object
  ```

MultiProvider

You can use multiplrovide through out the pogram

Syntax

  ```

Widget build(BuildContext context) { return MultiProvider( providers: [ ChangeNotifierProvider( create: (ctx) => ProductList(), ), ChangeNotifierProvider( create: (ctx) => ShoppingList(), ), ], ```

You will get the value through out the child class

Delete Cell Using swipe function

Widget name : Dismissible

Syntax

      ```
   Dismissible(
  key: ValueKey(item.product.id), // key which item will delete
  direction: DismissDirection.endToStart, // right to left
  onDismissed: (direction) { // function execute while delete the item
  },
  background: Container(
    color: Colors.blueAccent,
    child: Icon(
      Icons.delete,
      color: Colors.black,
      size: 40,
    ),
    alignment: Alignment.centerRight,
    padding: EdgeInsets.only(right: 20),
    margin: EdgeInsets.only(left: 10, right: 5, top: 2),
  )
  ```