[Javascript] Querying an Immutable.js Map()

提示：扫一扫查出行
【扫一扫了解最新限行尾号】
复制提示

Learn how to query an Immutable.Map() using get, getIn, has, includes, find, first and last. These are powerful operators that make finding data in an object graph pain free.

has, includes, contains:

//has()

var map = Immutable.Map({a: '10'});

console.log(map.has("a")); //true

//includes / contains

var todo = {

  id: +new Date(),

  name: "name",

  content: "content"

};

var todo2 = {

  id: +new Date(),

  name: "name",

  content: "content"

};

var todos = Immutable.Map();

todos = todos.set(todo.id, todo);

console.log(todos.contains(todo)); //true

console.log(todos.contains(todo2)); //false

first(), getIn()

// first(), getIn()

//Create tow Maps

var todos = Immutable.Map();

var todos2 = Immutable.Map();

//Create new Data

var todo1 = {

  id: +new Date(),

  name: "name",

  content: "content"

};

var todo2 = {

  id: +new Date()+1000,

  name: "name",

  content: "content"

};

var todo3 = {

  id: +new Date()+3000,

  name: "name",

  content: "content"

};

var todo4 = {

  id: +new Date()+4000,

  name: "name",

  content: "content"

};

//Add data to the map

todos =todos.set(todo1.id, todo1);

todos= todos.set(todo2.id, todo2);

todos2=todos2.set(todo3.id, todo3);

todos2=todos2.set(todo4.id, todo4);

//Wrap maps in another map

var multipleTodoStates = Immutable.Map({

    "todo1": todos,

    "todo2": todos2

});

//Get first todo's id in the first map

const todoID = todos.first().id;

console.log(todoID);

//Try to find the first todo in deep map

//"todo1" is the first level map

//then downto the second level to find the id

//If nohting return null

var res = multipleTodoStates.getIn(["todo1", todoID], null);

var res2 = multipleTodoStates.getIn(["todo2", todoID], null);

console.log(res);

console.log(res2);

find():

//find()

var todo = {

  id: +new Date(),

  name: "Wan",

  content: "Finish it"

};

var todos = Immutable.Map();

todos = todos.set(todo.id, todo);

var foundTodo = todos.find( (t)=>{

  return t.id === todo.id

}, null, null) ;

console.log(foundTodo.id);