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Flow Resolvers

This plugin generates resolvers signature based on your GraphQLSchema.

It generates types for your entire schema: types, input types, enum, interface, scalar and union.

This plugin requires you to use @graphql-codegen/flow as well, because it depends on it's types.

Installation

flow-resolvers plugin version
Using yarn
yarn add -D @graphql-codegen/flow-resolvers

API Reference

addUnderscoreToArgsType

type: boolean

Adds _ to generated Args types in order to avoid duplicate identifiers.

Usage Examples

config:
addUnderscoreToArgsType: true

contextType

type: string

Use this configuration to set a custom type for your context, and it will effect all the resolvers, without the need to override it using generics each time. If you wish to use an external type and import it from another file, you can use add plugin and add the required import statement, or you can use a module#type syntax.

Usage Examples

Custom Context Type
plugins
config:
contextType: MyContext
Custom Context Type
plugins
config:
contextType: ./my-types#MyContext

fieldContextTypes

type: Array_1

Use this to set a custom type for a specific field context. It will only affect the targeted resolvers. You can either use Field.Path#ContextTypeName or Field.Path#ExternalFileName#ContextTypeName

Usage Examples

Custom Field Context Types
plugins
config:
fieldContextTypes:
- MyType.foo#CustomContextType
- MyType.bar#./my-file#ContextTypeOne

rootValueType

type: string

Use this configuration to set a custom type for the rootValue, and it will effect resolvers of all root types (Query, Mutation and Subscription), without the need to override it using generics each time. If you wish to use an external type and import it from another file, you can use add plugin and add the required import statement, or you can use both module#type or module#namespace#type syntax.

Usage Examples

Custom RootValue Type
plugins
config:
rootValueType: MyRootValue
Custom RootValue Type
plugins
config:
rootValueType: ./my-types#MyRootValue

mapperTypeSuffix

type: string

Adds a suffix to the imported names to prevent name clashes.

Usage Examples

plugins
config:
mapperTypeSuffix: Model

mappers

type: object

Replaces a GraphQL type usage with a custom type, allowing you to return custom object from your resolvers. You can use both module#type and module#namespace#type syntax.

Usage Examples

Custom Context Type
plugins
config:
mappers:
User: ./my-models#UserDbObject
Book: ./my-models#Collections#Book

defaultMapper

type: string

Allow you to set the default mapper when it's not being override by mappers or generics. You can specify a type name, or specify a string in module#type or module#namespace#type format. The default value of mappers it the TypeScript type generated by typescript package.

Usage Examples

Replace with any
plugins
config:
defaultMapper: any
Custom Base Object
plugins
config:
defaultMapper: ./my-file#BaseObject
Wrap default types with Partial

You can also specify a custom wrapper for the original type, without overriding the original generated types, use "{T}" to specify the identifier. (for flow, use $Shape<{T}>)

plugins
config:
defaultMapper: Partial<{T}>
Allow deep partial with utility-types
plugins
plugins:
- "typescript"
- "typescript-resolvers"
- add:
content: "import { DeepPartial } from 'utility-types';"
config:
defaultMapper: DeepPartial<{T}>

avoidOptionals

type: AvoidOptionalsConfig | boolean default: false

This will cause the generator to avoid using optionals (?), so all field resolvers must be implemented in order to avoid compilation errors.

Usage Examples

Override all definition types
generates:
path/to/file.ts:
plugins:
- typescript
- typescript-resolvers
config:
avoidOptionals: true
Override only specific definition types
generates:
path/to/file.ts:
plugins:
- typescript
config:
avoidOptionals:
field: true
inputValue: true
object: true
defaultValue: true

showUnusedMappers

type: boolean default: true

Warns about unused mappers.

Usage Examples

generates:
path/to/file.ts:
plugins:
- typescript
- typescript-resolvers
config:
showUnusedMappers: true

enumValues

type: EnumValuesMap

Overrides the default value of enum values declared in your GraphQL schema, supported in this plugin because of the need for integration with typescript package. See documentation under typescript plugin for more information and examples.

resolverTypeWrapperSignature

type: string default: Promise<T> | T

Allow you to override resolverTypeWrapper definition.

federation

type: boolean default: false

Supports Apollo Federation

enumPrefix

type: boolean default: true

Allow you to disable prefixing for generated enums, works in combination with typesPrefix.

Usage Examples

Disable enum prefixes
config:
typesPrefix: I
enumPrefix: false

optionalResolveType

type: boolean default: false

Sets the __resolveType field as optional field.

immutableTypes

type: boolean default: false

Generates immutable types by adding readonly to properties and uses ReadonlyArray.

namespacedImportName

type: string default: ''

Prefixes all GraphQL related generated types with that value, as namespaces import. You can use this featuere to allow seperation of plugins to different files.

resolverTypeSuffix

type: string default: Resolvers

Suffix we add to each generated type resolver.

allResolversTypeName

type: string default: Resolvers

The type name to use when exporting all resolvers signature as unified type.

internalResolversPrefix

type: string default: '__'

Defines the prefix value used for __resolveType and and __isTypeOf resolvers. If you are using mercurius-js, please set this field to empty string for better compatiblity.

onlyResolveTypeForInterfaces

type: boolean default: false

Turning this flag to true will generate resolver siganture that has only resolveType for interfaces, forcing developers to write inherited type resolvers in the type itself.

scalars

type: ScalarsMap

Extends or overrides the built-in scalars and custom GraphQL scalars to a custom type.

namingConvention

type: NamingConvention default: change-case-all#pascalCase

Allow you to override the naming convention of the output. You can either override all namings, or specify an object with specific custom naming convention per output. The format of the converter must be a valid module#method. Allowed values for specific output are: typeNames, enumValues. You can also use "keep" to keep all GraphQL names as-is. Additionally you can set transformUnderscore to true if you want to override the default behavior, which is to preserves underscores.

Available case functions in change-case-all are camelCase, capitalCase, constantCase, dotCase, headerCase, noCase, paramCase, pascalCase, pathCase, sentenceCase, snakeCase, lowerCase, localeLowerCase, lowerCaseFirst, spongeCase, titleCase, upperCase, localeUpperCase and upperCaseFirst See more

typesPrefix

type: string default: ``

Prefixes all the generated types.

Usage Examples

config:
typesPrefix: I

typesSuffix

type: string default: ``

Suffixes all the generated types.

Usage Examples

config:
typesSuffix: I

skipTypename

type: boolean default: false

Does not add __typename to the generated types, unless it was specified in the selection set.

Usage Examples

config:
skipTypename: true

nonOptionalTypename

type: boolean default: false

Automatically adds __typename field to the generated types, even when they are not specified in the selection set, and makes it non-optional

Usage Examples

config:
nonOptionalTypename: true

useTypeImports

type: boolean default: false

Will use import type {} rather than import {} when importing only types. This gives compatibility with TypeScript's "importsNotUsedAsValues": "error" option

Usage Example#

Quick Start with flow-resolvers

You can find a blog post we wrote about using and customizing this plugin here , it refers to typescript-resolvers but everything there is relevant to flow-resolvers as well.

Enum Resolvers#

Apollo-Server and schemas built with graphql-tools supports creating resolvers for GraphQL enums.

This is helpful because you can have internal values that are different from the public enum values, and you can use the internal values in your resolvers.

Codegen allows you to specify either mappers or enumValues to map enums in your resolvers, and if you are using it for enums, you'll get a resolver signature for the enum resolvers as well.

Usage Example#

With the following schema:

type Query {
favoriteColor: Color!
}
type Color {
RED,
BLUE
}
schema: schema.graphql
generates:
./resolvers-types.js:
config:
enumValues:
Colors: ./enums#ColorsCode
plugins:
- flow
- flow-resolvers
// in your enums.js
export enum ColorsCode {
MY_RED = '#FF0000',
MY_BLUE = '#0000FF',
}
// in your resolvers.js
import type { Resolvers } from './resolvers-types';
import { ColorsCode } from './enums';
const resolvers: Resolvers = {
Colors: {
RED: ColorsCode.MY_RED,
BLUE: ColorsCode.MY_BLUE,
},
Query: {
favoriteColor: () => ColorsCode.MY_RED, // Now you cn return this, and it will be mapped to your actual GraphQL enum
}
}

You can also define the same with explicit enum values:

schema: schema.graphql
generates:
./resolvers-types.js:
config:
enumValues:
Colors:
RED: '#FF0000'
BLUE: '#0000FF'
plugins:
- flow
- flow-resolvers

Or, with mappers:

schema: schema.graphql
generates:
./resolvers-types.js:
config:
mappers:
Colors: ./enums#ColorsCode
plugins:
- flow
- flow-resolvers