Ledgerflow implementation

Legerflow connects to a variety of accounting service providers, and provides access to company accounts in a unified API. The Ledgerflow API uses Xero's OpenAPI syntax. So if your application can connect to Xero, Ledgerflow enables you to connect to a variety of other accounting software providers too with just the same client code.

This project is the Xero NetStandard OAuth 2.0 Starter App provided by Xero, with a few modifications to make it compatible with Ledgerflow too.

Usage with Ledgerflow

You'll need to start by creating an account with Ledgerflow. You can get started for free. See the Legerflow website for more.

You will then need to create a Partner App within Ledgerflow, including providing some details for the connection options that you want to make available to your users.

Your Partner App has a ClientId and ClientSecret, created for you when you created your Partner App. Update the appsettings.json in this project with these values. Also in appsettings.json, may also need to update the CallbackUrl for whatever port this project is running on. Make sure that in your Partner App settings within Ledgerflow, this CallbackUrl is on your list of permitted callback URLs for that app.

That should be all that you need to get your started, and enjoying using Ledgerflow to connect to a variety of accounting service providers through one unified interface.

Usage with Xero

The project works with Xero's API as well as with Ledgerflow. To use it with Xero, you'll need to:

• Register your developer app with Xero
• Update the project's appsettings.json with the ClientId and ClientSecret of your Xero developer app
• In appsettings.json, delete the three "...BaseUri" values so that it will default to using the xero.com endpoints

To delete the three "...BaseUri" values, delete the entirety of each line in which these keys appear: XeroApiBaseUri, XeroLoginBaseUri, XeroIdentityBaseUri. Also, on the "State" line immediately above those entries, you will have to delete the comma at the end of that line so that the appsettings.json file is still valid JSON.

Xero NetStandard OAuth 2.0 Starter App

This is a companion app built with .NET Core 3.1 MVC to demonstrate Xero OAuth 2.0 Client Authentication & OAuth 2.0 APIs.

IMPORTANT! This application is for demo only. We recommend setting up a secure token storage for your production app.

Its functions include:

• connect & reconnect to Xero
• storing Xero token in a .json file
• refresh Xero access token on expiry
• allow user to switch between tenants/organisations
• allow user to disconnect a tenant or revoke token
• allow manual testing of many Xero API endpoints
• display API call responses
• display code snippets responsible for the call

You can connect this companion app to an actual Xero organisation and make real API calls. Please use your Demo Company organisation for your testing. Here is how to turn it on.

Create a Xero app

You will need your Xero app credentials created to run this demo app.

To obtain your API keys, follow these steps:

• Create a free Xero user account (if you don't have one)
• Login to Xero developer center
• Click "New App" link
• Enter your App name, company url, privacy policy url.
• Enter the redirect URI (your callback url - i.e. https://localhost:5001/Authorization/Callback)
• Agree to terms and condition and click "Create App".
• Click "Generate a secret" button.
• Copy your client id and client secret and save for use later.
• Click the "Save" button. You secret is now hidden.

Download the code

Clone this repo to your local drive or open with GitHub desktop client.

Configure your API Keys

In /NetStandardApp/appsettings.json, you should populate your XeroConfiguration as such:

  "XeroConfiguration": {
    "ClientId": "YOUR_XERO_APP_CLIENT_ID",
    "ClientSecret": "YOUR_XERO_APP_CLIENT_SECRET",
    "CallbackUri": "https://localhost:5001/Authorization/Callback",
    "Scope": "openid offline_access profile ... ",
    "State": "YOUR_STATE"
  }

Note that you will have to have a state. The CallbackUri has to be exactly the same as redirect URI you put in Xero developer portal letter by letter.

Note that if Bankfeed and/or Finance API(s) is/are used with the example code, you must contact Xero via https://www.xero.com/uk/partner-programs/financialweb/contact/ for access request. If not, then just remove the finance API scopes from Scope variable in the json file.

Getting started with dotnet & command line

You can run this application with dotnet SDK from command line.

Install dotnet SDK

Download and install dotnet SDK on your machine.

Verify in command line by:

$ dotnet --version
3.1.102

Build the project

Change directory to NetStandardApp directory where you can see XeroNetStandardApp.csproj, build the project by:

$ dotnet build
Microsoft (R) Build Engine version 16.4.0+e901037fe for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.
.
.
.

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:02.22

Run the project

In /NetStandardApp, run the project by:

$ dotnet run
info: Microsoft.Hosting.Lifetime[0]
      Now listening on: https://localhost:5001
info: Microsoft.Hosting.Lifetime[0]
      Now listening on: http://localhost:5000
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: /Users/.../Xero-NetStandard-App/XeroNetStandardApp

Test the project

Open your browser, type in https://localhost:5001

Getting started with Visual Studio Code

You can also run it using an IDE such as VS Code with C# extension installed.

Install VS Code

Download an install VS Code and open the project root folder with it.

Go to Extensions, install C# extension by OmniSharp.

Build the project

Go back to Explorer and press F5 (or go to Debug > Start Debugging). It will ask you for environment for launch configuration. Select .NET Core.

Save the launch.json, then press F5 again to run.

You should see following in the DEBUG CONSOLE and be directed to your default browser with https://localhost:5001 already open.

Start your Testing.

Some explanation of the code

HomeController

• checks if there is a xerotoken.json, and
• passes a boolean firstTimeConnection to view to control the display of buttons.

AuthorizationController

• reads XeroConfiguration & make httpClientFactory available via dependency injection
• on /Authorization/, redirects user to Xero OAuth for authentication & authorization
• receives callback on /Authorization/Callback request Xero token
• gets connected tenants (organisations)
• store token via a public static method TokenUtilities.StoreToken(xeroToken);

AssetsInfoController

• makes API call to assets endpoint (Asset API)
• displays all current Fixed Assets (GET)
• allows for creation of Fixed Asset (PUT)

AuEmployeesInfoController

• makes API call to employees endpoint (PayrollAu API)
• displays all current AU employees (GET)
• allows for creation of a new Employee (PUT)

BankfeedConnectionsController

• makes API call to feed connections endpoint (BankFeeds API)
• displays all current feed connections (GET), allows for deletion (POST)
• allows for creation of new feed connection (PUT)

BankfeedStatementsController

• makes API call to statements endpoint (BankFeeds API)
• displays all current statements (GET)
• allows for creation of new statement (PUT)

BankTransactionsInfoController

• makes API call to bank transactions endpoint (Accounting API)
• displays all current bank transactions (GET)

ContactInfoController

• makes api call to contacts endpoint
• displays in view
• static view Create.cshtml creates a web form and POST contact info to Create() action, and
• makes an create operation to contacts endpoint

IdentityInfoController

• gets the list of tenant connections
• displays tenant information (GET /connections)
• allows user to disconnect a specific tenant (DELETE /connections/{id})

InvoiceSyncController

• gets invoices in the last 7 days and displays them in view (GET /invoices)
• allows user to upload attachments to a specific invoice (POST {id}/attachments)

NzEmployeesInfoController

• gets a list of employees in NZ Payroll (GET)
• displays them in view
• allows user to create new employees (POST)

OrganisationInfoController

• gets the current organisation information (GET)
• displays in view

ProjectInfoController

• gets the list of projects in Xero projects (GET)
• displays in view

PurchaseOrderSyncController

• gets a list of purchase orders (GET)
• displays in view
• allows user to create a new purchase order (POST)

UkEmployeeInfoController

• gets a list of employees in Uk Payroll (GET)
• displays them in view
• allows user to create new employees (POST)

FilesSyncController

• makes API call to files endpoint (Files API)
• displays all current files (GET)
• allows for upload of new files (POST)
• can modify existing files (GET /FilesSync/{fileId})
• can delete existing files (PUT)

FoldersSyncController

• makes API call to folders endpoint (Files API)
• displays all current folders (GET)
• allows user to create new folders (POST)
• can modify existing folders (GET /FoldersSync/{folderId})
• can delete existing folders (PUT)

AssociationsSyncController

• makes API call to associations endpoint (Files API)
• displays all current associations (GET)
• allows user to create new associations (POST)
• can delete existing folders (PUT)

Xero token is stored in a JSON file in the root of the project "./xerotoken.json". The app serialise and deserialise with the static class functions in /Utilities/TokenUtilities.cs. Most controllers will get and refresh token before calling API methods.

Cross Site Forgery Attack Example

For demonstrating OAuth 2.0 CSFR implementation, two static methods were created to handle local storage of current state (state.json): TokenUtilities.StoreState(string state) and TokenUtilities.GetCurrentState().

In AuthenticationController, on construction it generates a random GUID string as state. The Index() will store the state to state.json, then be retrieved on Callback(). If state does not match, the controller returns a warning "Cross site forgery attack detected!" instead of carrying forward the token request flow.

License

This software is published under the MIT License.

Copyright (c) 2020 Xero Limited

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.