@leancodepl/cqrs-client-base

Base types and interfaces for CQRS clients.

Installation

npm install @leancodepl/cqrs-client-base
# or
yarn add @leancodepl/cqrs-client-base

API

TokenProvider

Interface for token providers used in CQRS clients.

Properties:

• getToken: () => Promise<string | undefined> - Returns authentication token
• invalidateToken: () => Promise<boolean> - Invalidates and refreshes token

ValidationError<TErrorCodes>

Represents validation errors from commands.

Properties:

• PropertyName: string - Property that failed validation
• ErrorMessage: string - Human-readable error message
• ErrorCode: TErrorCodes[keyof TErrorCodes] - Error code from provided map

CommandResult<TErrorCodes>

Union type for command results.

Types:

• SuccessfulCommandResult - When command succeeds
• FailedCommandResult<TErrorCodes> - When command fails with validation errors

ApiResponse<TResult>

Union type for API responses.

Types:

• ApiSuccess<TResult> - Successful response with result
• ApiError - Error response

Usage Examples

Token Provider Implementation

import { TokenProvider } from "@leancodepl/cqrs-client-base"

const tokenProvider: TokenProvider = {
  getToken: async () => {
    return localStorage.getItem("authToken")
  },
  invalidateToken: async () => {
    localStorage.removeItem("authToken")
    return true
  },
}

Command Error Handling

import { CommandResult, ValidationError } from "@leancodepl/cqrs-client-base"

interface UserErrorCodes {
  EmailExists: 1
  InvalidEmail: 2
}

function handleCommandResult(result: CommandResult<UserErrorCodes>) {
  if (result.WasSuccessful) {
    console.log("Command succeeded")
  } else {
    result.ValidationErrors.forEach((error: ValidationError<UserErrorCodes>) => {
      console.log(`${error.PropertyName}: ${error.ErrorMessage}`)
    })
  }
}

API Response Handling

import { ApiResponse } from "@leancodepl/cqrs-client-base"

function handleApiResponse<T>(response: ApiResponse<T>) {
  if (response.isSuccess) {
    return response.result
  } else {
    throw new Error("API call failed")
  }
}