How to handle object vs Array in Interface effectively

Question

I am running into an issue with a data Interface. My API returns me the data in a format which looks something like this

export interface IApiResponse {
    Success: boolean;
    Error: string;
    Message: string;
    RowCount: number;
    Data: [];
  }

this works fine as long as the Data is actually an array which is often the case. But when I get lets say the detail of a contact it is only a object in Data which is not an array. So my question is there a way to handle this or is the only way to create 2 interfaces where one is for a response where data is array the other when it is object.

You can specify two types like this: Data: Array | Object

Kardon63
– Kardon63

2020-10-19 19:18:32 +00:00
Commented Oct 19, 2020 at 19:18 — Kardon63
– Kardon63, Commented Oct 19, 2020 at 19:18

ericgio · Accepted Answer · 2020-10-19 19:22:33Z

1

You can pass a data type by defining the interface as follows:

export interface IApiResponse<T> {
  Success: boolean;
  Error: string;
  Message: string;
  RowCount: number;
  Data: T;
}

Then depending on your API endpoint, you can specify the type:

function someApiCall(): IApiResponse<MyDataType[]> {
  ...
}

answered Oct 19, 2020 at 19:22

ericgio

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2 Comments

Confused Coder Over a year ago

That works, i am wondering is there a way to use a default Datatype if T is not provided ? I am asking to see if there is a easy way to migrate which makes T optional and if T is not provided it would default to array.

ericgio Over a year ago

@ConfusedCoder: You should be able to do something like interface IApiResponse<T = any[]> { ... }

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