Is there a way in Typescript to extract values from JSON objects within an array, even when the property names are constantly changing?

Question

Is there a way in Typescript to extract values from JSON objects within an array, even when the property names are constantly changing?

As a newcomer to typescript, I am looking for a way to extract values from JSON objects within an array that have changing property names.

The code I have (simplified) is as follows:

const gridData = [
  { "source_language": "en", "word": "man", "character_grid": [["i", "q", "\u00ed", "l", "n", "n", "m", "\u00f3"], ["f", "t", "v", "\u00f1", "b", "m", "h", "a"], ... ], "target_language": "es" },
  ...
];

const gridDataInUse = gridData[0];

const selectedLetters = [{x: 6, y: 1, l: "h"}, {x: 6, y: 2, l: "o"}, ...]

const letterCoordinates: number[] = []
selectedLetters.forEach((letter => {
    letterCoordinates.push(letter.x);
    letterCoordinates.push(letter.y);
}));
const letterCoordinatesAsString = letterCoordinates.join(',');
const selectedWord = selectedLetters.map((letter) => {
    return letter.l;
}).join('');
console.log(gridDataInUse.word_locations[letterCoordinatesAsString]);

In this example, my intention is to retrieve the value "hombre" from the first JSON object in the array.

However, I encountered the following error message:

Element implicitly has an 'any' type because expression of type 'string' can't be used to index type '{ "6,1,6,2,6,3,6,4,6,5,6,6": string; ... No index signature with a parameter of type 'string' was found on type '{ "6,1,6,2,6,3,6,4,6,5,6,6": string; ...

Can you guide me on how to resolve this error?

Thank you very much for your assistance!

javascript typescript

Answer 1

Answer №1

For better compatibility with TypeScript, it is recommended to provide a type for your array as the comma in the word_location object might be causing confusion. Here's an example of how you can define the type:

interface gridItem {
    source_language: string,
    word: string,
    character_grid: Array<Array<string>>
    word_locations: Record<string, string>,
    target_language: string
}

const gridData:Array<gridItem> = [
  // Data objects here... 
];

// Sample usage
const gridDataInUse = gridData[0];

// Selected letters
const selectedLetters = [{x: 6, y: 1, l: "h"}, {x: 6, y: 2, l: "o"}, /* more letter objects */ ];

const letterCoordinates: number[] = []
selectedLetters.forEach((letter => {
    letterCoordinates.push(letter.x);
    letterCoordinates.push(letter.y);
}));
const letterCoordinatesAsString = letterCoordinates.join(',');
const selectedWord = selectedLetters.map((letter) => {
    return letter.l;
}).join('');
console.log(gridDataInUse.word_locations[letterCoordinatesAsString]);

If you'd like to see a working code example without errors, you can check out the link provided below.

View Working Code Example

Answer 2

For better compatibility with TypeScript, it is recommended to provide a type for your array as the comma in the word_location object might be causing confusion. Here's an example of how you can define the type:

interface gridItem {
    source_language: string,
    word: string,
    character_grid: Array<Array<string>>
    word_locations: Record<string, string>,
    target_language: string
}

const gridData:Array<gridItem> = [
  // Data objects here... 
];

// Sample usage
const gridDataInUse = gridData[0];

// Selected letters
const selectedLetters = [{x: 6, y: 1, l: "h"}, {x: 6, y: 2, l: "o"}, /* more letter objects */ ];

const letterCoordinates: number[] = []
selectedLetters.forEach((letter => {
    letterCoordinates.push(letter.x);
    letterCoordinates.push(letter.y);
}));
const letterCoordinatesAsString = letterCoordinates.join(',');
const selectedWord = selectedLetters.map((letter) => {
    return letter.l;
}).join('');
console.log(gridDataInUse.word_locations[letterCoordinatesAsString]);

If you'd like to see a working code example without errors, you can check out the link provided below.

View Working Code Example

Answer 3

Answer №2

If you are completely sure that each letterCoordinatesAsString you create will match a property in the object being examined, a simple solution is to specify in TypeScript that the word_locations object is of type Record<string, string>. This allows you to access the object using your letterCoordinatesAsString string:

const gridData: Array<{
    source_language: string;
    word: string;
    // ...
    word_locations: Record<string, string>;
}> = [
  { "source_language": "en", ...

TypeScript does not handle dynamic property names very gracefully. Another approach could be using a type assertion after an in check to confirm if the property exists on the object, indicating to the programmer that it is safe to access without providing TypeScript additional inference data:

const { word_locations } = gridDataInUse;
if (letterCoordinatesAsString in word_locations) {
    console.log((word_locations as Record<string, string | undefined>)[letterCoordinatesAsString]);
}

Applying as const typing could simplify things, converting the word_locations from a union (including possible undefined values) into the type of a straightforward object. While this may not make a difference when logging the result, it enables TypeScript to infer the value as a string rather than string | undefined, eliminating the need for the cumbersome as assertion.

const gridData = [
  { "source_language": "en", "word": ...
] as const;
// ...
if (letterCoordinatesAsString in word_locations) {
    console.log(word_locations[letterCoordinatesAsString]);
}

Answer 4

If you are completely sure that each letterCoordinatesAsString you create will match a property in the object being examined, a simple solution is to specify in TypeScript that the word_locations object is of type Record<string, string>. This allows you to access the object using your letterCoordinatesAsString string:

const gridData: Array<{
    source_language: string;
    word: string;
    // ...
    word_locations: Record<string, string>;
}> = [
  { "source_language": "en", ...

TypeScript does not handle dynamic property names very gracefully. Another approach could be using a type assertion after an in check to confirm if the property exists on the object, indicating to the programmer that it is safe to access without providing TypeScript additional inference data:

const { word_locations } = gridDataInUse;
if (letterCoordinatesAsString in word_locations) {
    console.log((word_locations as Record<string, string | undefined>)[letterCoordinatesAsString]);
}

Applying as const typing could simplify things, converting the word_locations from a union (including possible undefined values) into the type of a straightforward object. While this may not make a difference when logging the result, it enables TypeScript to infer the value as a string rather than string | undefined, eliminating the need for the cumbersome as assertion.

const gridData = [
  { "source_language": "en", "word": ...
] as const;
// ...
if (letterCoordinatesAsString in word_locations) {
    console.log(word_locations[letterCoordinatesAsString]);
}

Answer 5

Answer №3

There seems to be an issue with the structure of your JSON. To correct it, you may need to add some curly brackets as shown below:

const info = [
          { details: { "2,3": "Sarah" }},
          { details: { "3,4": "Emily", "4,5": "David" }},
          { details: { "5,6": "Chris", "6,7": "Sophia" }}
         ];

Check out the corrected code on JSFiddle: https://jsfiddle.net/b9dACj2s/

Answer 6

There seems to be an issue with the structure of your JSON. To correct it, you may need to add some curly brackets as shown below:

const info = [
          { details: { "2,3": "Sarah" }},
          { details: { "3,4": "Emily", "4,5": "David" }},
          { details: { "5,6": "Chris", "6,7": "Sophia" }}
         ];

Check out the corrected code on JSFiddle: https://jsfiddle.net/b9dACj2s/

Is there a way in Typescript to extract values from JSON objects within an array, even when the property names are constantly changing?

Answer №1

Answer №2

Answer №3

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