使用linqjs使用另一个数组中的值过滤一个数组

Question

The first one is an array of objects:

let objectArray = [{
    FullName: "Person1",
    PersonId: "id1"
  },
  {
    FullName: "Person2",
    PersonId: "id2"
  },
  {
    FullName: "Person3",
    PersonId: "id3"
  },
  {
    FullName: "Person4",
    PersonId: "id4"
  }
];

The second one is an array of strings containing some ids.

let idsArray= ["id1", "id2", "id3"];

I need to delete the objects of the first array whose id are contained in the second array.

Expected result:

firstArray = [{
  FullName: "Person4",
  PersonId: "id4"
}];

Exploring Linqjs documentation I discovered that the Except() method allows me to remove elements from the first array using the second one as the "filter".

In order to use this method, I need to create a new array from objectArray that contains only the elements whose ids are contained on idsArray to use it as a parameter.

Example:

let filteredArray = Enumerable.From(objectArray).Except(theNewArray).ToArray();

To create this new array I can use the method Where() from Linqjs .

My problem starts here because I don't know how to create this new array considering that I have an array of ids to filter.

Answer 1

You can use filter() to filter the array. Use new Set() to create a set object. This will make easier to check if the PersonId exists. No need to loop every filter()

 let objectArray = [ {FullName: "Person1",PersonId: "id1"}, {FullName: "Person2",PersonId: "id2"}, {FullName: "Person3",PersonId: "id3"}, {FullName: "Person4",PersonId: "id4"} ]; let idsArray = ["id1", "id2", "id3"]; let idsToRemove = new Set(idsArray); let result = objectArray.filter(o => !idsToRemove.has(o.PersonId)); console.log(result); 

Another option is using includes() to test if an array includes a certain string.

 let objectArray = [ {FullName: "Person1",PersonId: "id1"}, {FullName: "Person2",PersonId: "id2"}, {FullName: "Person3",PersonId: "id3"}, {FullName: "Person4",PersonId: "id4"} ]; let idsArray = ["id1", "id2", "id3"]; let result = objectArray.filter(o => !idsArray.includes(o.PersonId)); console.log(result); 

---

Note: If you dont want a new variable, you can override the existing variable as:

objectArray = objectArray.filter(o => ...);

Answer 2

You can use Vanilla JavaScript's array.filter and array.includes like this:

 let objectArray = [ {FullName: "Person1", PersonId: "id1"}, {FullName: "Person2", PersonId: "id2"}, {FullName: "Person3", PersonId: "id3"}, {FullName: "Person4", PersonId: "id4"} ]; let excludeIdsArray= ["id1", "id2", "id3"]; let newObj = objectArray.filter(obj => !excludeIdsArray.includes(obj.PersonId)) console.log(newObj) 

Or , you can use array.reduce and array.includes like this:

 let objectArray = [ {FullName: "Person1", PersonId: "id1"}, {FullName: "Person2", PersonId: "id2"}, {FullName: "Person3", PersonId: "id3"}, {FullName: "Person4", PersonId: "id4"} ]; let excludeIdsArray= ["id1", "id2", "id3"]; let newObj = objectArray.reduce((arr, myObject) => { if(!excludeIdsArray.includes(myObject.PersonId)) { arr.push(myObject) } return arr }, []) console.log(newObj) 

Answer 3

You can use Array.prototype.filter method in conjunction with indexOf to test if the PersonId property is found in the array of IDs to exclude - if it's not, add it to the new filteredArray . See below for example:

 let objects = [{ FullName: "Person1", PersonId: "id1" }, { FullName: "Person2", PersonId: "id2" }, { FullName: "Person3", PersonId: "id3" }, { FullName: "Person4", PersonId: "id4" } ]; let toDelete = ["id1", "id2", "id3"]; //just use Array.prototype.filter method to remove unwanted var filteredObjects = objects.filter(function(element) { return toDelete.indexOf(element.PersonId) === -1; }); console.log(filteredObjects); 

This is achieved using vanilla JavaScript. I would advise you remove linqjs from your project's codebase if this is the only thing you're using it for.

Answer 4

You could take Except of linq.js with an array of objects and a column parameter to exclude the unwanted PersonId .

 var objectArray = [{ FullName: "Person1", PersonId: "id1" }, { FullName: "Person2", PersonId: "id2" }, { FullName: "Person3", PersonId: "id3" }, { FullName: "Person4", PersonId: "id4" }], idsArray = ["id1", "id2", "id3"], result = Enumerable .From(objectArray) .Except( Enumerable.From(idsArray).Select("{ PersonId: $ }"), "$.PersonId" ) .ToArray(); console.log(result); 

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