Utilities

Utils are utility functions that can be used in hooks or anywhere else in your Feathers application. They can be used to perform common tasks such as mutating data, validating input, or formatting output.

Utility	Description
addSkip	Adds hook names to context.params.skipHooks so that skippable-wrapped hooks will be bypassed for the current service call. Accepts a single name or an array. Duplicates are automatically removed.
addToQuery	Safely merges properties into a Feathers query object. If a property already exists with a different value, it wraps both in a $and array to preserve both conditions. If the exact same key-value pair already exists, no changes are made.
checkContext	Validates that the hook context matches the expected type(s) and method(s). Throws an error if the context is invalid, preventing hooks from running in unsupported configurations. Typically used internally by other hooks.
contextToJson	Converts a FeathersJS HookContext to a plain JSON object by calling toJSON() if available. This is important when using lodash get/has on the context, since the HookContext class uses getters that may not be enumerable.
defineHooks	TypeScript helper that provides full type inference and autocompletion when defining service hooks. It is an identity function that simply returns its input, but enables your IDE to infer the correct hook context types.
getDataIsArray	Normalizes context.data into an array for uniform processing. Returns { data, isArray } where data is always an array and isArray indicates whether the original value was already an array.
getExposedMethods	Returns the list of method names that are publicly exposed by a Feathers service. Reads the internal [SERVICE].methods property set during service registration. Throws if the service does not have any exposed methods configured.
getPaginate	Resolves the active pagination options for the current hook context. Checks (in order): context.params.paginate, service.options.paginate, and context.params.adapter.paginate. Returns undefined if pagination is disabled.
getResultIsArray	Normalizes context.result (or context.dispatch) into an array for uniform processing. Handles paginated results by extracting the data array. Returns { result, isArray, key } where key indicates whether 'result' or 'dispatch' was used.
iterateFind	Use for await to iterate over the results of a find method. This function is useful for iterating over large datasets without loading everything into memory at once. It uses pagination to fetch results in chunks, allowing you to process each item as it is retrieved.
mutateData	Applies a transformer function to each item in context.data, updating it in place. If the transformer returns a new object, it replaces the original item. Correctly handles both single-item and array data, preserving the original shape.
mutateResult	Applies a transformer function to each item in context.result (and optionally context.dispatch). Handles paginated results, single items, and arrays transparently. Use the dispatch option to control whether result, dispatch, or both are transformed.
patchBatch	Batch patching utility that takes an array of items to be changed and returns an array of arguments to be called with the patch method. This utility is useful when you need to patch multiple items with varying data in as few requests as possible.
skipResult	Sets context.result to an appropriate empty value based on the hook method. Returns an empty paginated object for paginated find, an empty array for multi operations, or null for single-item operations. Does nothing if a result already exists.
toPaginated	Ensures a result is in Feathers paginated format ({ total, limit, skip, data }). If the input is already paginated, it is returned as-is. If it is a plain array, it is wrapped in a paginated object with total and limit set to the array length.
transformParams	Safely applies a transformParams function to a params object. If no function is provided, the original params are returned unchanged. The function receives a shallow copy of params, so the original is not mutated.
walkQuery	Walks every property of a Feathers query (including nested $and/$or/$nor/$not arrays) and calls the walker function for each one. The walker receives the property name, operator, value, and path, and can return a replacement value. Returns a new query only if changes were made.