I have a class Person and after setting its properties, figuring out best way to convert that class to json object.
class Person {
firstName: string;
lastName: string;
}
let person = new Person();
person.firstName = "FirstName";
person.lastName = "LastName";
If i do person.getJson() it should give json object as given below
{
"firstName": "FirstName",
"lastName": "LastName"
}
and incase lastName is not set then json object should only have firstName
{
"firstName": "FirstName"
}
You don't need a getJson() method on class Person.
You can just call
JSON.stringify(person);
If you really want to put in your class...
class Person {
firstName: string;
lastName: string;
getJson() {
return JSON.stringify(this);
}
}
Related
I would like to create an instance of the Customer class from Json object.
But using the plainToInstance function of class-transformer I don't have the proper class instance as a type save typescript object.
What I'm doing bad?
Import
import { plainToInstance } from 'class-transformer';
Customer JSON
const json = `{
"id": "1",
"name": "Jogn",
"surname": "Doe",
"email": "j.doe.test#gmail.com",
"phone": "123456789"
}
}
`;
Customer class definition
import { Field, ObjectType, Directive, ID } from '#nestjs/graphql';
import { Address } from './address';
#ObjectType()
#Directive('#key(fields: "id")')
export class Customer {
#Field(() => ID)
id: string;
#Field()
name: String;
#Field({nullable: true})
surname?: String;
#Field()
email: String;
#Field({nullable: true})
phone?: String;
#Field()
customerType: String;
#Field()
customerStatus: String;
#Field(() => [Address], { nullable: true })
addresses?: [Address]
}
Transformation from Json to Customer instance
let customer : Customer = plainToInstance(Customer, json) as Customer;
console.log('customer.email);
Console result
Customer email: undefined
So I couldn't get the email of the customer here
This is what I have when I log the entire customer variable
console.log(customer);
{
"id": "1",
"name": "Jogn",
"surname": "Doe",
"email": "j.doe.test#gmail.com",
"phone": "123456789"
}
Test with creating the Customer instance inline
var x = new Customer();
x.id = "123";
console.log(x)
So, now the object looks properly in the console
Customer { id: '123' }
You must pass a json object to plainToInstance - not a string.
i.e. your json variable should be
const json = {
id: '1',
name: 'Jogn',
surname: 'Doe',
email: 'j.doe.test#gmail.com',
phone: '123456789',
};
here's a working Stackblitz example
The second attribute of plainToInstance should be a plain object so you have to parse your json string into an object:
let customer = plainToInstance(Customer, JSON.parse(json))
I have a class, for example, let's say a Car with the below structure.
#Serializable()
export default class Car {
#JsonProperty({
name: 'id'
})
private id!: string;
#JsonProperty({
name: 'name'
})
private name!: string;
#JsonProperty({
name: 'carOwner'
})
private carOwner!: Owner;
}
Further I have the Owner class.
#Serializable()
export default class Owner{
#JsonProperty({
name: 'id'
})
private id!: string;
#JsonProperty({
name: 'name'
})
private name!: string;
#JsonProperty({
name: 'address'
})
private address!: string;
}
I have an incoming JSON Object with below structure, let's call it newCar
{
"id": "test-id",
"name": "test-car",
"carOwner": {
"id": "owner-id",
"name": "owner-name",
"address": "owner-address",
"gender": "owner-gender",
"age": "owner-age",
}
}
What I want to do is, deserialize the newCar JSON to the Car class. That is when I deserialize newJson I should get the below object, where gender and age are filtered out.
{
"id": "test-id",
"name": "test-car",
"carOwner": {
"id": "owner-id",
"name": "owner-name",
"address": "owner-address"
}
}
But right now what I am getting is the original newJson. It seems that the library (typescript-json-serializer) which I am using does not deserialize nested objects, here which is owner.
Any input will be appreciated.
Here is the link to the package typescript-json-serializer
Found the solution for it. Apparently I missed to add one parameter in JsonProperty().
In the Car class, for carOwner object, I had to pass type of owner.
#JsonProperty({
name: 'carOwner',
type: Owner,
})
The above solved the issue I was facing.
This question already has answers here:
How do I cast a JSON Object to a TypeScript class?
(28 answers)
How to parse a JSON object to a TypeScript Object
(11 answers)
How do I initialize a TypeScript Object with a JSON-Object?
(18 answers)
Closed 1 year ago.
I'm using Angular to call an external API. Json data is in format like:
[
{
"AccessGroupsIdList": [],
"FirstName": "Greg",
"LastName": "Tipton",
"LocationIdList": [],
"PermissionProfile": {
"Name": "Agent",
"PermissionProfileId": {
"ID": "xy678219-bd7c-103d-b56b-1f1234a85990"
},
"Type": 3
},
"ManagerName": "Gilchrist, George",
"Status": true,
"UserGroupID": {
"ID": "00000000-0000-0000-0000-000000000000"
},
"UserGroupName": "ROOT",
"UserId": {
"ID": "4445cc66-819a-4da0-8fbf-d0bb8ce65941"
}
}
]
How do I create a class in typescript to read it since json data is nested?
export class Employees
{
AccessGroupsIdList: string[];
FirstName: string;
LastName: string;
LocationIdList : number[];
PermissionProfile ??
ManagerName: string;
Status: boolean;
UserGroupID ??
UserGroupName : string;
UserId ??
}
Please guide if the PermissionProfile, PermissionProfile will be separate nested classes?
How do I declare those?
To extend Andrew Halil's answer, I would use interfaces instead of classes in your definitions, since there do not appear to be any class methods involved; you are just describing the shape of a JSON object returned from a server
export interface Employee
{
AccessGroupsIdList: string[];
FirstName: string;
LastName: string;
LocationIdList : number[];
PermissionProfile: PermissionProfile;
ManagerName: string;
Status: boolean;
UserGroupId: ID;
UserGroupName : string;
UserId: ID;
}
export interface PermissionProfile
{
name: string;
permissionProfileId: ID;
type: string;
}
export interface ID
{
id: string;
}
Now as for an implementation, I don't use Angular all that much but you would do something like this to get the items typed
async function listEmployees(): Promise<Employee[]> {
// Make a fetch call to the API endpoint
const data = await fetch('https://some-api-endpoint.web/employees')
// if the response comes back ok, return the JSON-ified response.
.then(res => {
if(res.ok) return res.json()
return [];
});
// Instruct typescript that "data" is to be treated as an array of Employee elements.
return data as Employee[]
}
Try declaring the Typescript class structures as follows:
export class Employees
{
AccessGroupsIdList: string[];
FirstName: string;
LastName: string;
LocationIdList : number[];
PermissionProfile: PermissionProfile;
ManagerName: string;
Status: boolean;
UserGroupId: UserGroupID;
UserGroupName : string;
UserId: UserID;
}
export class PermissionProfile
{
name: string;
permissionProfileId: PermissionProfileID;
type: string;
}
export class PermissionProfileID
{
id: string;
}
export class UserGroupID
{
id: string;
}
export class UserID
{
id: string;
}
I would suggest to name the property names consistently with an Id (e.g. with UserGroupId). The name and type class property names are valid in TypeScript (unlike with the C# syntax).
I have a class which has multiple interfaces inside of it to model a JSON data. For example:
interface A {
id: number;
}
interface B {
name: string;
surname?: string;
}
class MyClass implements A {
people: B[];
notes: string[];
function1(){...}
function2(){...}
}
And I have a JSON in the same structure:
{
id: 1,
people: [
{
name: "john"
},
{
name: "alice",
surname: "smith"
}
],
notes: [ "Very important top secret note" ]
}
Can I create an instance of MyClass from this JSON directly?
Your data structure is almost the same as your class, you'd have to add an id property to the class
class MyClass implements A {
id: number;
// ....
}
The problem is if you were trying to do something like this:
let data: MyClass = {
id: 1,
people: [
{
name: "john"
},
{
name: "alice",
surname: "smith"
}
],
notes: [ "Very important top secret note" ]
}
This won't work because your json does not have the methods (function1, function2).
One solution would be to really instantiate the MyClass and pass the json, or have a constructor method for that like
class MyClass {
static createFrom(jsonData: A & B): MyClass {
// create the objct and return
}
}
Or, you could create a variable of that type by combining an existing instance of the class and spreading the json.
Like so:
let json = {
id: 1,
people: [
{
name: "john"
},
{
name: "alice",
surname: "smith"
}
],
notes: ["Very important top secret note"]
}
const c = new MyClass();
let mClass: MyClass = {...json, function1: c.function1, function2: c.function2 };
mClass.function1();
Link to playground
Let be this JSON string:
[
{
"id": 1,
"text": "Jon Doe"
},
{
"id": 1,
"text": "Pablo Escobar"
}
]
Let be this class:
export class MyObject{
id: number;
text: string;
}
How can I cast this JSON string to list of MyObject?
If I do:
console.log(<MyObject[]>JSON.parse(json_string));
It returns a list of Object instead of a list of MyObject
You don't necessarily need a class here. You can just use an interface
export interface MyObject{
id: number;
text: string;
}
Then you can just write:
var myObjArray : MyObject[] = [
{
"id": 1,
"text": "Jon Doe"
},
{
"id": 1,
"text": "Pablo Escobar"
}
];
If you data comes from the server, you will probably have it in a variable of type any, and you can just assign it to an array of that type and it will work as expected.
var data: any = getFromServer();
var myObjectArray:MyObject[] = data;
In typescript you don't need a class implementing an interface. Any object literal that satisfies the interface contract will do.
If your data is still in string for you can just use JSON.parse(jsonString) to parse the string to JavaScript objects.
See playground here
You will need to create a constructor for your class, and call it for each item in the list you receive.
export class MyObject{
constructor(public id: number, public text: string) { }
}
let data = [
{
"id": 1,
"text": "Jon Doe"
},
{
"id": 1,
"text": "Pablo Escobar"
}
];
let objects = data.map(o => new MyObject(o.id, o.text));
You can check it out in the playground here.
There is a problem when MyObject has 50 or more properties...
Add a constructor in your MyObject class so that it extends your json object.
export class MyObject {
constructor( json: any )
{
$.extend(this, json);
}
id : number;
text : string;
methodOnMyObject() {...}
}
In your ajax callback, create the MyObject object from your json Object:
let newObject = new MyObject( json );
newObject.methodOnMyObject();
I detailed the solution in that post.
One more way to achieve this:
var data: any = getFromServer();
var myObjectArray = data as MyObject;
Or:
var data: any = getFromServer();
var myObjectArray = <MyObject>dataMyObject;