How to map json objects to typescript arrays

Question

I have tried various examples but none has worked so far. I have a GET response as follows:

{data: {…}, status: 200, statusText: "OK", headers: {…}, config: {…}, …} config: {adapter: ƒ, transformRequest: {…}, transformResponse: {…}, timeout: 0, xsrfCookieName: "XSRF-TOKEN", …}

data:

sales: Array(2) 0: {Id: 2, Amount: 500, DateCreated: "01/01/2019 00:00:00"} 1: {Id: 3, Amount: 410, DateCreated: "01/20/2019 00:00:00"}

I have an interface definition as follows:

interface ISales{
  id:number;
  amount:number;
  dateCreated:Date
}

I want to create an array and fill in the values from the response sales. I have tried the following:

 const result: ISales = response.data.sales;
      let payments: ISales[];
      payments = [];
      payments.push(result);


payments.map((item)=>{"whole array", console.log(item)})

payments.map((item)=>{"property only", console.log(item.amount)})

In the above the whole array displays the data right as

(2) [{…}, {…}] 0: {Id: 2, Amount: 500, DateCreated: "01/01/2019 00:00:00"} 1: {Id: 3, Amount: 410, DateCreated: "01/20/2019 00:00:00"} length: 2 proto: Array(0)

Whereas the property only is undefined. What is wrong with my code. How can I read the property value and store it in payments?

payment is empty, set it ->payments = result;

Chanaka Weerasinghe
– Chanaka Weerasinghe

2019-06-25 11:07:34 +00:00
Commented Jun 25, 2019 at 11:07 — Chanaka Weerasinghe
– Chanaka Weerasinghe, Commented Jun 25, 2019 at 11:07

jupiter sailormoon · Accepted Answer · 2019-06-26 09:17:16Z

1

I finally managed to find the error. The properties in the interface were camel case whereas, those from the response were pascal case.

answered Jun 26, 2019 at 9:17

jupiter sailormoon

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Comments

Aston · Accepted Answer · 2019-06-25 11:11:30Z

0

This should work:

const result: ISales[] = response.data.sales;
result.map((isales: ISales)=>{console.log(isales)});
result.map((isales: ISales)=>{console.log(isales.amount)});

answered Jun 25, 2019 at 11:11

Aston

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1 Comment

jupiter sailormoon Over a year ago

It gives the errorerror: TypeError: Cannot read property 'map' of undefined at localhost:3000/static/js/bundle.js:67569:24 at step (localhost:3000/static/js/bundle.js:63911:23) at Object.next message: "Cannot read property 'map' of undefined" stack: "TypeError: Cannot read property 'map' of undefined↵ at proto: Error

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