How to map an object from JSON file to another object? - json

Question

Here is my json file
{
"data": [
{
"firstName": "Tom",
"lastName": "Yoda",
"type": "guest",
"id": "0",
"gender": m,
"data": { "age": 26, "born": "UK" }
},
]
}
This data array could have more entries.
I have to map the values into an interface which looks like:
InterfacePerson {
id: string;
title: string;
firstName: string;
lastName: string;
age: string;
location: string;
}
I am unable to change the interface. So I'm trying to do some pseudo coding.
const list;
list = convertToInterfacePerson = (value): Array<InterfacePerson> => {
return {
id: value.id,
title: if(value.gender === "m")? "Mr" : "Mrs",
firstName: value.firstName,
lastName: value.lastName,
age: value.data.age,
//...
}
}

Answer 1

I think you were trying to use a conversion mapping function called convertToInterfacePerson but you hadn't set it up yet (separately from trying to use it). The code below shows it declared and used within a map Array method call. I believe this resolves the error(s) you were getting.
// Copied in the JSON for demonstration
const sourceJson = {
"data": [
{
"firstName": "Tom",
"lastName": "Yoda",
"type": "guest",
"id": "0",
"gender": "m",
"data": { "age": 26, "born": "UK" }
},
]
};
// Declared the InterfacePerson interface
interface InterfacePerson {
id: string;
title: string;
firstName: string;
lastName: string;
age: string;
location: string;
}
// Declared the conversion mapping function (optional parameter typing included)
const convertToInterfacePerson = (value: { firstName: string, lastName: string, type: string, id: string, gender: string, data: { age: number, born: string } }): InterfacePerson => {
return {
id: value.id,
// Removed the `if` statement due to ternary conditional
title: ((value.gender === "m") ? "Mr" : "Mrs"),
firstName: value.firstName,
lastName: value.lastName,
// Wrapped the value.data.age in a string conversion
age: String(value.data.age),
location: value.data.born
};
}
// Declared and assigned the list based on the returned array from the mapping function (each element is applied in the `convertToInterfacePerson` function)
const list = sourceJson.data.map(convertToInterfacePerson);
// Show the result of the conversion
console.log(JSON.stringify(list, null, 2));
And for a live example, check out this TypeScript Playground script containing this solution.