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guards

Type guard utilities for common validation patterns.

This module consolidates reusable type guards that are used throughout the codebase for validating GraphQL schema objects and other entities.

hasArrayProperty()​

Call Signature​

function hasArrayProperty<K>(obj, key): obj is Record<K, unknown[]>;

Defined in: guards.ts:111

Type guard to check if an object has an array property.

Type Parameters​

K​

K extends PropertyKey

Parameters​

obj​

unknown

The object to check

key​

K

The property name to look for

Returns​

obj is Record<K, unknown[]>

true if the property exists and is an array, false otherwise

Example​

import { hasArrayProperty } from "@graphql-markdown/utils/guards";

if (hasArrayProperty(type, "args")) {
  // type.args is now typed as unknown[]
  console.log(type.args.length);
}

Call Signature​

function hasArrayProperty(obj, key): obj is Record<PropertyKey, unknown[]>;

Defined in: guards.ts:116

Type guard to check if an object has an array property.

Parameters​

obj​

unknown

The object to check

key​

PropertyKey

The property name to look for

Returns​

obj is Record<PropertyKey, unknown[]>

true if the property exists and is an array, false otherwise

Example​

import { hasArrayProperty } from "@graphql-markdown/utils/guards";

if (hasArrayProperty(type, "args")) {
  // type.args is now typed as unknown[]
  console.log(type.args.length);
}

hasFunctionProperty()​

Call Signature​

function hasFunctionProperty<K>(
  obj,
  key,
): obj is Record<K, (args: unknown[]) => unknown>;

Defined in: guards.ts:213

Type guard to check if an object has a function property.

Type Parameters​

K​

K extends PropertyKey

Parameters​

obj​

unknown

The object to check

key​

K

The property name to look for

Returns​

obj is Record<K, (args: unknown[]) => unknown>

true if the property exists and is a function, false otherwise

Example​

import { hasFunctionProperty } from "@graphql-markdown/utils/guards";

if (hasFunctionProperty(directive, "descriptor")) {
  // directive.descriptor is now typed as a function
  directive.descriptor();
}

Call Signature​

function hasFunctionProperty(
  obj,
  key,
): obj is Record<PropertyKey, (args: unknown[]) => unknown>;

Defined in: guards.ts:218

Type guard to check if an object has a function property.

Parameters​

obj​

unknown

The object to check

key​

PropertyKey

The property name to look for

Returns​

obj is Record<PropertyKey, (args: unknown[]) => unknown>

true if the property exists and is a function, false otherwise

Example​

import { hasFunctionProperty } from "@graphql-markdown/utils/guards";

if (hasFunctionProperty(directive, "descriptor")) {
  // directive.descriptor is now typed as a function
  directive.descriptor();
}

hasNonEmptyArrayProperty()​

Call Signature​

function hasNonEmptyArrayProperty<K>(obj, key): obj is Record<K, unknown[]>;

Defined in: guards.ts:145

Type guard to check if an object has a non-empty array property.

Type Parameters​

K​

K extends PropertyKey

Parameters​

obj​

unknown

The object to check

key​

K

The property name to look for

Returns​

obj is Record<K, unknown[]>

true if the property exists, is an array, and is non-empty, false otherwise

Example​

import { hasNonEmptyArrayProperty } from "@graphql-markdown/utils/guards";

if (hasNonEmptyArrayProperty(type, "args")) {
  // type.args is a non-empty array
  const firstArg = type.args[0];
}

Call Signature​

function hasNonEmptyArrayProperty(
  obj,
  key,
): obj is Record<PropertyKey, unknown[]>;

Defined in: guards.ts:150

Type guard to check if an object has a non-empty array property.

Parameters​

obj​

unknown

The object to check

key​

PropertyKey

The property name to look for

Returns​

obj is Record<PropertyKey, unknown[]>

true if the property exists, is an array, and is non-empty, false otherwise

Example​

import { hasNonEmptyArrayProperty } from "@graphql-markdown/utils/guards";

if (hasNonEmptyArrayProperty(type, "args")) {
  // type.args is a non-empty array
  const firstArg = type.args[0];
}

hasProperties()​

function hasProperties<K>(obj, ...keys): obj is Record<K, unknown>;

Defined in: guards.ts:82

Type guard to check if an object has multiple specific properties.

Type Parameters​

K​

K extends PropertyKey

Parameters​

obj​

unknown

The object to check

keys​

...K[]

The property names to look for

Returns​

obj is Record<K, unknown>

true if the object has all the properties, false otherwise

Example​

import { hasProperties } from "@graphql-markdown/utils/guards";

if (hasProperties(type, "name", "description")) {
  // Both properties exist on type
  console.log(type.name, type.description);
}

hasProperty()​

Call Signature​

function hasProperty<K>(obj, key): obj is Record<K, unknown>;

Defined in: guards.ts:48

Type guard to check if an object has a specific property.

Type Parameters​

K​

K extends PropertyKey

Parameters​

obj​

unknown

The object to check

key​

K

The property name to look for

Returns​

obj is Record<K, unknown>

true if the object has the property, false otherwise

Example​

import { hasProperty } from "@graphql-markdown/utils/guards";

if (hasProperty(type, "args")) {
  // type.args is now accessible
  console.log(type.args);
}

Call Signature​

function hasProperty(obj, key): obj is Record<PropertyKey, unknown>;

Defined in: guards.ts:53

Type guard to check if an object has a specific property.

Parameters​

obj​

unknown

The object to check

key​

PropertyKey

The property name to look for

Returns​

obj is Record<PropertyKey, unknown>

true if the object has the property, false otherwise

Example​

import { hasProperty } from "@graphql-markdown/utils/guards";

if (hasProperty(type, "args")) {
  // type.args is now accessible
  console.log(type.args);
}

hasStringProperty()​

Call Signature​

function hasStringProperty<K>(obj, key): obj is Record<K, string>;

Defined in: guards.ts:179

Type guard to check if an object has a string property.

Type Parameters​

K​

K extends PropertyKey

Parameters​

obj​

unknown

The object to check

key​

K

The property name to look for

Returns​

obj is Record<K, string>

true if the property exists and is a string, false otherwise

Example​

import { hasStringProperty } from "@graphql-markdown/utils/guards";

if (hasStringProperty(type, "description")) {
  // type.description is now typed as string
  console.log(type.description.length);
}

Call Signature​

function hasStringProperty(obj, key): obj is Record<PropertyKey, string>;

Defined in: guards.ts:184

Type guard to check if an object has a string property.

Parameters​

obj​

unknown

The object to check

key​

PropertyKey

The property name to look for

Returns​

obj is Record<PropertyKey, string>

true if the property exists and is a string, false otherwise

Example​

import { hasStringProperty } from "@graphql-markdown/utils/guards";

if (hasStringProperty(type, "description")) {
  // type.description is now typed as string
  console.log(type.description.length);
}

isNonEmptyArray()​

function isNonEmptyArray(value): value is unknown[];

Defined in: guards.ts:246

Type guard to check if a value is a non-empty array.

Parameters​

value​

unknown

The value to check

Returns​

value is unknown[]

true if the value is an array with at least one element

Example​

import { isNonEmptyArray } from "@graphql-markdown/utils/guards";

if (isNonEmptyArray(values)) {
  // values is now typed as unknown[] with at least one element
  console.log(values[0]);
}

isTypeObject()​

function isTypeObject(obj): obj is Record<string, unknown>;

Defined in: guards.ts:27

Type guard to check if a value is an object but not an array.

Parameters​

obj​

unknown

The value to check

Returns​

obj is Record<string, unknown>

true if the value is a non-null object but not an array, false otherwise

Example​

import { isTypeObject } from "@graphql-markdown/utils/guards";

if (isTypeObject(value)) {
  // value is now typed as Record<string, unknown> and is not an array
  // (includes Date, Map, and other object types)
  console.log(Object.keys(value));
}