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Function: extractFieldWithFallbackPath()

Gala Launchpad SDK 9.0.0-rc.5

Gala Launchpad SDK 9.0.0-rc.5 / index / extractFieldWithFallbackPath

Function: extractFieldWithFallbackPath()

extractFieldWithFallbackPath<T>(obj, fieldPaths, defaultValue?): T | null

Defined in: packages/launchpad-sdk/dist/utils/data-transform-patterns.d.ts:176

Extract field value from object using fallback path chain

Tries multiple field paths in order (both flat and nested) and returns the first one that has a non-empty value. Supports nested paths like "response.data.error" for deep object traversal.

Consolidates repeated response-handler field extraction and fallback logic.

Note: extractFieldWithCandidates() already exists in object-extractors.ts for simple field name candidates. This function extends that pattern to support nested paths (dot-notation) for deeper object traversal.

Type Parameters​

T​

T = unknown

Type of the default value (inferred from defaultValue parameter)

Parameters​

obj​

unknown

Object to extract field from (can be any type, will check for object)

fieldPaths​

string[]

Array of field paths to try in order (e.g., ['id', 'error.code', 'response.data.message'])

defaultValue?​

T

Value to return if no field path has a value (default: null)

Returns​

T | null

First non-empty value found, or defaultValue if none found

Examples​

Basic field extraction

const obj = { id: '123', transactionId: null };

const id = extractFieldWithFallbackPath(obj, ['id', 'transactionId']);
// Returns: '123'

With nested paths

const response = {
  data: {
    error: {
      code: 'VALIDATION_ERROR'
    }
  }
};

const errorCode = extractFieldWithFallbackPath(
  response,
  ['error.code', 'code', 'message'],
  'UNKNOWN'
);
// Returns: 'VALIDATION_ERROR'

With default value

const obj = { name: null };

const name = extractFieldWithFallbackPath(
  obj,
  ['name', 'displayName', 'title'],
  'Unknown'
);
// Returns: 'Unknown' (all paths empty, uses default)

With type-safe default

const obj = { count: null };

const count: number = extractFieldWithFallbackPath(
  obj,
  ['count', 'total', 'size'],
  0
);
// Returns: 0 (type inferred from defaultValue)

Error case - non-object input

const value = extractFieldWithFallbackPath(null, ['field'], null);
// Returns: null (input is null, not an object)