TypeScript errors when using Redux-Form with React-Redux connect

Question

I was falling in love with TypeScript until I found some very discouraging incompatibilities between Redux-Form with React-Redux.

My goal is wrap a reduxForm decorated component with the react-redux connect decorator—this pattern has always worked for me in babel configurations and seems to follow the HOC methodology. Here's an example:

import * as React from 'react';
import { Dispatch } from 'redux';
import { connect } from 'react-redux';
import { reduxForm, Field, InjectedFormProps } from 'redux-form';

interface SampleFormData {
  username: string;
}

interface SampleFormProps {
  saveData: (data: SampleFormData) => void;
}

type AllSampleFormProps = SampleFormProps & InjectedFormProps<SampleFormData>;

const SampleForm: React.SFC<AllSampleFormProps> = (props) => (
  <form onSubmit={props.handleSubmit(props.saveData)}>
    <Field name="username" component="input" />
  </form>
);

const DecoratedSampleForm = reduxForm<SampleFormData>({ form: "sampleForm" })(SampleForm);

export default connect(
  () => ({}),
  (dispatch) => ({
    saveData: (data: SampleFormData) => dispatch({ type: "SAVE_DATA", data })
  })
)(DecoratedSampleForm);

Here's the errors TypeScript is throwing:

> Argument of type 'DecoratedComponentClass<SampleFormData,
> Partial<ConfigProps<SampleFormData, {}>>>' is not assignable to
> parameter of type 'ComponentType<{ saveData: (data: SampleFormData) =>
> { type: string; data: SampleFormData; }; }>'.
> 
> Type 'DecoratedComponentClass<SampleFormData,
> Partial<ConfigProps<SampleFormData, {}>>>' is not assignable to type
> 'StatelessComponent<{ saveData: (data: SampleFormData) => { type:
> string; data: SampleFormData; };...'.
> 
> Type 'DecoratedComponentClass<SampleFormData,
> Partial<ConfigProps<SampleFormData, {}>>>' provides no match for the
> signature '(props: { saveData: (data: SampleFormData) => { type:
> string; data: SampleFormData; }; } & { children?: ReactNode; },
> context?: any): ReactElement<any>'.

Has anyone found a solution to make react-redux accept the DecoratedComponentClass type? I found a suggestion to use a "middle" component but I haven't managed to get this to work with thunk actions. Plus I've found that this creates more problems than it solves in terms of typing the form's props.

Answer 1

To anyone who comes across this, I found that I was able to dismiss the error by providing the connect statement with empty TStateProps and TDispatchProps objects.

interface SampleFormData {
  username: string;
}

interface SampleFormProps {
  saveData: (data: SampleFormData) => void;
}

type AllSampleFormProps = SampleFormProps & InjectedFormProps<SampleFormData>;

const SampleForm: React.SFC<AllSampleFormProps> = (props) => (
  <form onSubmit={props.handleSubmit(props.saveData)}>
    <Field name="username" component="input" />
  </form>
);

const DecoratedSampleForm = reduxForm<SampleFormData>({ form: "sampleForm" })(SampleForm);

export default connect<{},{}>(
  () => ({}),
  (dispatch) => ({
    saveData: (data: SampleFormData) => dispatch({ type: "SAVE_DATA", data })
  })
)(DecoratedSampleForm);

The one downside to this is that it forces us to blindly supply connect props but I felt that this was a more elegant solution than writing an override @types declaration.

To address this shortcoming, I was able to validate the types by providing connect with the correct interfaces versus empty objects; however, this method can only be done temporarily to check the bindings as it doesn't resolve the DecoratedComponentClass error.

export default connect<{}, SampleFormProps, InjectedFormProps<SampleFormData>>(
  () => ({}),
  (dispatch) => ({
    saveData: (data: SampleFormData) => dispatch({ type: "SAVE_DATA", data })
  })
)(DecoratedSampleForm);

Answer 2

A higher Component Interface declaration does the trick that wraps up connects Type with component state and props Type using a decorator.

connect.ts

import * as React from "react";
import {
  connect as originalConnect,
  MapStateToPropsParam,
  MergeProps,
  Options
} from "react-redux";
import { IState } from "./index";

export interface IDisPatchProps {
  [key: string]: () => void;
}

export type InferableComponentEnhancerWithProps<TInjectedProps, TNeedsProps> = <
  TComponent extends React.ComponentType<TInjectedProps & TNeedsProps>
>(
  component: TComponent
) => TComponent;

export interface IConnectProps {
  <TStateProps = {}, TDispatchProps = {}, TOwnProps = {}>(
    mapStateToProps?: MapStateToPropsParam<TStateProps, TOwnProps, IState>,
    mapDispatchToProps?: IDisPatchProps
  ): InferableComponentEnhancerWithProps<
    TStateProps & TDispatchProps,
    TOwnProps
  >;

  <TStateProps = {}, TDispatchProps = {}, TOwnProps = {}, TMergedProps = {}>(
    mapStateToProps?: MapStateToPropsParam<TStateProps, TOwnProps, IState>,
    mapDispatchToProps?: IDisPatchProps,
    mergeProps?: MergeProps<
      TStateProps,
      TDispatchProps,
      TOwnProps,
      TMergedProps
    >,
    options?: Options<TStateProps, TOwnProps, TMergedProps>
  ): InferableComponentEnhancerWithProps<TMergedProps, TOwnProps>;
}

declare module "react-redux" {
  // tslint:disable-next-line
  interface Connect extends IConnectProps {}
}

export const connect = originalConnect as IConnectProps;


 ***ClassFile***

 @connect(
  (state: IState): IStateProps => ({
    count: state.counter.count,
    isLoading: state.counter.isLoading
  }),
  {
    decrement,
    increment
  }
)
export default class MyApp

Link: https://github.com/TomasHubelbauer/react-redux-typescript-connect-decorator-demo/blob/master/my-app/src/connect.ts

credit goes to: TomasHubelbauer https://github.com/TomasHubelbauer