mirror of
https://github.com/XRPLF/xrpl-dev-portal.git
synced 2026-04-29 15:37:48 +00:00
merge master in, resolve conflicts
This commit is contained in:
akcodez
@@ -240,7 +240,7 @@ Save the taker pays and taker gets fields; use these values to get the total amo
|
||||
}
|
||||
```
|
||||
|
||||
Use [AMM helper functions](https://github.com/XRPLF/rippled/blob/2d1854f354ff8bb2b5671fd51252c5acd837c433/src/ripple/app/misc/impl/AMMHelpers.cpp) to estimate values for:
|
||||
Implement [AMM formulas](https://github.com/XRPLF/rippled/blob/master/src/xrpld/app/misc/detail/AMMHelpers.cpp) to estimate values for:
|
||||
|
||||
- Cost to swap token without an auction slot.
|
||||
- Cost to swap token with an auction slot.
|
||||
@@ -534,7 +534,7 @@ Report the results.
|
||||
|
||||
## Code Walkthrough (ripplex13b-amm-formulas.js)
|
||||
|
||||
You can open `ripplex13b-amm-formulas.js` from the [Quickstart Samples](https://github.com/XRPLF/xrpl-dev-portal/tree/master/_code-samples/quickstart/js/) to view the source code. This tutorial uses three of the available [AMM helper functions](https://github.com/XRPLF/rippled/blob/2d1854f354ff8bb2b5671fd51252c5acd837c433/src/ripple/app/misc/impl/AMMHelpers.cpp).
|
||||
You can open `ripplex13b-amm-formulas.js` from the [Quickstart Samples](https://github.com/XRPLF/xrpl-dev-portal/tree/master/_code-samples/quickstart/js/) to view the source code. This code implements several core [AMM formulas](https://github.com/XRPLF/rippled/blob/master/src/xrpld/app/misc/detail/AMMHelpers.cpp) defined by the protocol.
|
||||
|
||||
|
||||
### swapOut()
|
||||
|
||||
@@ -62,10 +62,10 @@ Click **Download** on the top right of the code preview panel to download the so
|
||||
|
||||
Follow the steps to create a simple application with `xrpl.js`.
|
||||
|
||||
### 1. Install Dependencies
|
||||
|
||||
<!-- Web steps -->
|
||||
{% step id="import-web-tag" when={ "environment": "Web" } %}
|
||||
### 1. Install Dependencies
|
||||
|
||||
To load `xrpl.js` into your project, add a `<script>` tag to your HTML.
|
||||
|
||||
You can load the library from a CDN as in the example, or download a release and host it on your own website.
|
||||
@@ -74,7 +74,8 @@ This loads the module into the top level as `xrpl`.
|
||||
{% /step %}
|
||||
|
||||
<!-- Node.js steps -->
|
||||
{% step id="install-node-tag" when={ "environment": "Node" } %}
|
||||
{% step id="import-node-tag" when={ "environment": "Node" } %}
|
||||
### 1. Install Dependencies
|
||||
|
||||
Start a new project by creating an empty folder, then move into that folder and use [NPM](https://www.npmjs.com/) to install the latest version of xrpl.js:
|
||||
|
||||
@@ -94,7 +95,7 @@ Your `package.json` file should look something like this:
|
||||
{% step id="connect-tag" %}
|
||||
#### Connect to the XRP Ledger Testnet
|
||||
|
||||
To make queries and submit transactions, you need to connect to the XRP Ledger. To do this with `xrpl.js`, you create an instance of the `Client` class and use the `connect()` method.
|
||||
To make queries and submit transactions, you need to connect to the XRP Ledger. To do this with `xrpl.js`, you create an instance of the [`Client`](https://js.xrpl.org/classes/Client.html) class and use the [`connect()`](https://js.xrpl.org/classes/Client.html#connect) method.
|
||||
|
||||
{% admonition type="success" name="Tip" %}Many network functions in `xrpl.js` use [Promises](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) to return values asynchronously. The code samples here use the [`async/await` pattern](https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Asynchronous/Async_await) to wait for the actual result of the Promises.{% /admonition %}
|
||||
|
||||
@@ -130,46 +131,48 @@ The sample code shows you how to connect to the Testnet, which is one of the ava
|
||||
{% step id="get-account-create-wallet-tag" %}
|
||||
#### Create and Fund a Wallet
|
||||
|
||||
The `xrpl.js` library has a `Wallet` class for handling the keys and address of an XRP Ledger account. On Testnet, you can fund a new account as shown in the example.
|
||||
The `xrpl.js` library has a [`Wallet`](https://js.xrpl.org/classes/Wallet.html) class for handling the keys and address of an XRP Ledger account. On Testnet, you can fund a new account as shown in the example.
|
||||
{% /step %}
|
||||
|
||||
{% step id="get-account-create-wallet-b-tag" %}
|
||||
#### (Optional) Generate a Wallet Only
|
||||
|
||||
If you want to generate a wallet without funding it, you can create a new `Wallet` instance. Keep in mind that you need to send XRP to the wallet for it to be a valid account on the ledger.
|
||||
If you want to generate a wallet without funding it, you can create a new [`Wallet`](https://js.xrpl.org/classes/Wallet.html) instance. Keep in mind that you need to send XRP to the wallet for it to be a valid account on the ledger.
|
||||
{% /step %}
|
||||
|
||||
{% step id="get-account-create-wallet-c-tag" %}
|
||||
#### (Optional) Use Your Own Wallet Seed
|
||||
|
||||
To use an existing wallet seed encoded in [base58][], you can create a `Wallet` instance from it.
|
||||
To use an existing wallet seed encoded in [base58][], you can create a [`Wallet`](https://js.xrpl.org/classes/Wallet.html) instance from it.
|
||||
{% /step %}
|
||||
|
||||
### 4. Query the XRP Ledger
|
||||
|
||||
{% step id="query-xrpl-tag" %}
|
||||
Use the Client's `request()` method to access the XRP Ledger's [WebSocket API](../../../references/http-websocket-apis/api-conventions/request-formatting.md).
|
||||
{% /step %}
|
||||
### 4. Query the XRP Ledger
|
||||
|
||||
### 5. Listen for Events
|
||||
Use the Client's [`request()`](https://js.xrpl.org/classes/Client.html#request) method to access the XRP Ledger's [WebSocket API](../../../references/http-websocket-apis/api-conventions/request-formatting.md).
|
||||
{% /step %}
|
||||
|
||||
{% step id="listen-for-events-tag" %}
|
||||
You can set up handlers for various types of events in `xrpl.js`, such as whenever the XRP Ledger's [consensus process](../../../concepts/consensus-protocol/index.md) produces a new [ledger version](../../../concepts/ledgers/index.md). To do that, first call the [subscribe method][] to get the type of events you want, then attach an event handler using the `on(eventType, callback)` method of the client.
|
||||
### 5. Listen for Events
|
||||
|
||||
You can set up handlers for various types of events in `xrpl.js`, such as whenever the XRP Ledger's [consensus process](../../../concepts/consensus-protocol/index.md) produces a new [ledger version](../../../concepts/ledgers/index.md). To do that, first call the [subscribe method][] to get the type of events you want, then attach an event handler using the [`on(eventType, callback)`](https://js.xrpl.org/classes/Client.html#on) method of the client.
|
||||
{% /step %}
|
||||
|
||||
{% step id="disconnect-node-tag" when={ "environment": "Node" } %}
|
||||
### 6. Disconnect
|
||||
|
||||
{% step id="disconnect-node-tag" when={ "environment": "Node" } %}
|
||||
Disconnect when done so Node.js can end the process. The example code waits 10 seconds before disconnecting to allow time for the ledger event listener to receive and display events.
|
||||
Call the [`disconnect()`](https://js.xrpl.org/classes/Client.html#disconnect) function so Node.js can end the process. The example code waits 10 seconds before disconnecting to allow time for the ledger event listener to receive and display events.
|
||||
{% /step %}
|
||||
|
||||
{% step id="disconnect-web-tag" when={ "environment": "Web" } %}
|
||||
Disconnect from the ledger when done. The example code waits 10 seconds before disconnecting to allow time for the ledger event listener to receive and display events.
|
||||
### 6. Disconnect
|
||||
|
||||
Call the [`disconnect()`](https://js.xrpl.org/classes/Client.html#disconnect) function to disconnect from the ledger when done. The example code waits 10 seconds before disconnecting to allow time for the ledger event listener to receive and display events.
|
||||
{% /step %}
|
||||
|
||||
{% step id="run-app-node-tag" when={ "environment": "Node" } %}
|
||||
### 7. Run the Application
|
||||
|
||||
{% step id="run-app-node-tag" when={ "environment": "Node" } %}
|
||||
Finally, in your terminal, run the application like so:
|
||||
|
||||
```sh
|
||||
@@ -237,6 +240,8 @@ Disconnected
|
||||
{% /step %}
|
||||
|
||||
{% step id="run-app-web-tag" when={ "environment": "Web" } %}
|
||||
### 7. Run the Application
|
||||
|
||||
Open the `index.html` file in a web browser.
|
||||
|
||||
You should see output similar to the following:
|
||||
|
||||
@@ -4,8 +4,7 @@ seo:
|
||||
labels:
|
||||
- Credentials
|
||||
---
|
||||
|
||||
# Verify Credentials in Javascript
|
||||
# Verify Credentials
|
||||
|
||||
This tutorial describes how to verify that an account holds a valid [credential](/docs/concepts/decentralized-storage/credentials) on the XRP Ledger, which has different use cases depending on the type of credential and the meaning behind it. A few possible reasons to verify a credential include:
|
||||
|
||||
@@ -13,297 +12,109 @@ This tutorial describes how to verify that an account holds a valid [credential]
|
||||
- Checking a person's professional certifications, after verifying their identity with a [DID](/docs/concepts/decentralized-storage/decentralized-identifiers).
|
||||
- Displaying a player's achievements in a blockchain-connected game.
|
||||
|
||||
This tutorial uses sample code in Javascript using the [xrpl-js library](../index.md).
|
||||
## Goals
|
||||
|
||||
By following this tutorial, you should learn how to:
|
||||
|
||||
- Fetch a Credential entry from the ledger.
|
||||
- Recognize if a credential has been accepted and when it has expired.
|
||||
|
||||
## Prerequisites
|
||||
|
||||
- You must have Node.js installed and know how to run Javascript code from the command line. Node.js v18 is required for xrpl.js.
|
||||
- You should have a basic understanding of the XRP Ledger.
|
||||
- The credential you want to verify should exist in the ledger already, and you should know the addresses of both the issuer and the holder, as well as the official credential type you want to check.
|
||||
- For sample code showing how to create credentials, see [Build a Credential Issuing Service](../build-apps/credential-issuing-service.md).
|
||||
To complete this tutorial, you should:
|
||||
|
||||
- Have a basic understanding of the XRP Ledger.
|
||||
- Have an XRP Ledger client library, such as [xrpl.js](../build-apps/get-started.md), installed.
|
||||
- Know the issuer, subject, and credential type of the credential you want to verify. For purposes of this tutorial, you can use sample values of data that exists in the public network.
|
||||
- For information on how to create your own credentials, see the [Build a Credential Issuing Service](../build-apps/credential-issuing-service.md) tutorial.
|
||||
|
||||
## Setup
|
||||
## Source Code
|
||||
|
||||
First, download the complete sample code for this tutorial from GitHub:
|
||||
You can find the complete source code for this tutorial's examples in the {% repo-link path="_code-samples/verify-credential/" %}code samples section of this website's repository{% /repo-link %}.
|
||||
|
||||
- {% repo-link path="_code-samples/verify-credential/js/" %}Verify Credential sample code{% /repo-link %}
|
||||
## Steps
|
||||
|
||||
Then, in the appropriate directory, install dependencies:
|
||||
|
||||
```sh
|
||||
npm install
|
||||
```
|
||||
|
||||
This installs the appropriate version of the `xrpl.js` library and a few other dependencies. You can view all dependencies in the {% repo-link path="_code-samples/verify-credentials/js/package.json" %}`package.json`{% /repo-link %} file.
|
||||
|
||||
## Overview
|
||||
|
||||
The Verify Credential sample code consists of one file, `verify_credential.js`, and contains two main parts:
|
||||
|
||||
1. A function, `verifyCredential(...)` which can be called with appropriate arguments to verify that a credential exists and is valid. This function can be imported into other code to be used as part of a larger application.
|
||||
2. A commandline utility that can be used to verify any credential.
|
||||
|
||||
## Usage
|
||||
|
||||
To test that you have the code installed and working properly, you can run the commandline utility with no arguments to check the existence of a default credential on Devnet, such as:
|
||||
|
||||
```sh
|
||||
node verify_credential.js
|
||||
```
|
||||
|
||||
If all goes well, you should see output such as the following:
|
||||
|
||||
```text
|
||||
info: Encoded credential_type as hex: 5465737443726564656E7469616C
|
||||
info: Looking up credential...
|
||||
info: {
|
||||
"command": "ledger_entry",
|
||||
"credential": {
|
||||
"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
|
||||
"issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
|
||||
"credential_type": "5465737443726564656E7469616C"
|
||||
},
|
||||
"ledger_index": "validated"
|
||||
}
|
||||
info: Found credential:
|
||||
info: {
|
||||
"CredentialType": "5465737443726564656E7469616C",
|
||||
"Flags": 65536,
|
||||
"Issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
|
||||
"IssuerNode": "0",
|
||||
"LedgerEntryType": "Credential",
|
||||
"PreviousTxnID": "B078C70D17820069BDF913146F9908A209B4E10794857A3E474F4C9C5A35CA6A",
|
||||
"PreviousTxnLgrSeq": 1768183,
|
||||
"Subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
|
||||
"SubjectNode": "0",
|
||||
"index": "F2ACB7292C4F4ACB18010251F1653934DC17F06AA5BDE7F484F65B5A648D70CB"
|
||||
}
|
||||
info: Credential is valid.
|
||||
```
|
||||
|
||||
If the code reports that the credential was not found when called with no arguments, it's possible that the example credential has been deleted or the Devnet has been reset. If you have another credential you can verify, you can provide the details as commandline arguments. For example:
|
||||
|
||||
```sh
|
||||
node verify_credential.js rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3 rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG TestCredential
|
||||
```
|
||||
|
||||
A full usage statement is available with the `-h` flag.
|
||||
|
||||
### Other Examples
|
||||
|
||||
The following examples show other possible scenarios. The data for these examples may or may not still be present in Devnet. For example, anyone can delete an expired credential.
|
||||
### 1. Install dependencies
|
||||
|
||||
{% tabs %}
|
||||
{% tab label="Valid with Expiration" %}
|
||||
```text
|
||||
$ ./verify_credential.js rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3 rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG TCredential777
|
||||
{% tab label="JavaScript" %}
|
||||
From the code sample folder, use `npm` to install dependencies:
|
||||
|
||||
info: Encoded credential_type as hex: 5443726564656E7469616C373737
|
||||
info: Looking up credential...
|
||||
info: {
|
||||
"command": "ledger_entry",
|
||||
"credential": {
|
||||
"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
|
||||
"issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
|
||||
"credential_type": "5443726564656E7469616C373737"
|
||||
},
|
||||
"ledger_index": "validated"
|
||||
}
|
||||
info: Found credential:
|
||||
info: {
|
||||
"CredentialType": "5443726564656E7469616C373737",
|
||||
"Expiration": 798647105,
|
||||
"Flags": 65536,
|
||||
"Issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
|
||||
"IssuerNode": "0",
|
||||
"LedgerEntryType": "Credential",
|
||||
"PreviousTxnID": "D32F66D1446C810BF4E6310E21111C0CE027140292347F0C7A73322F08C07D7E",
|
||||
"PreviousTxnLgrSeq": 2163057,
|
||||
"Subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
|
||||
"SubjectNode": "0",
|
||||
"URI": "746573745F757269",
|
||||
"index": "6E2AF1756C22BF7DC3AA47AD303C985026585B54425E7FACFAD6CD1867DD39C2"
|
||||
}
|
||||
info: Credential has expiration: 2025-04-22T14:25:05.000Z
|
||||
info: Looking up validated ledger to check for expiration.
|
||||
info: Most recent validated ledger is: 2025-04-22T13:47:30.000Z
|
||||
info: Credential is valid.
|
||||
```
|
||||
{% /tab %}
|
||||
{% tab label="Expired" %}
|
||||
```text
|
||||
$ ./verify_credential.js rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3 rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG TCredential777
|
||||
|
||||
info: Encoded credential_type as hex: 5443726564656E7469616C373737
|
||||
info: Looking up credential...
|
||||
info: {
|
||||
"command": "ledger_entry",
|
||||
"credential": {
|
||||
"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
|
||||
"issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
|
||||
"credential_type": "5443726564656E7469616C373737"
|
||||
},
|
||||
"ledger_index": "validated"
|
||||
}
|
||||
info: Found credential:
|
||||
info: {
|
||||
"CredentialType": "5443726564656E7469616C373737",
|
||||
"Expiration": 798647105,
|
||||
"Flags": 65536,
|
||||
"Issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
|
||||
"IssuerNode": "0",
|
||||
"LedgerEntryType": "Credential",
|
||||
"PreviousTxnID": "D32F66D1446C810BF4E6310E21111C0CE027140292347F0C7A73322F08C07D7E",
|
||||
"PreviousTxnLgrSeq": 2163057,
|
||||
"Subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
|
||||
"SubjectNode": "0",
|
||||
"URI": "746573745F757269",
|
||||
"index": "6E2AF1756C22BF7DC3AA47AD303C985026585B54425E7FACFAD6CD1867DD39C2"
|
||||
}
|
||||
info: Credential has expiration: 2025-04-22T14:25:05.000Z
|
||||
info: Looking up validated ledger to check for expiration.
|
||||
info: Most recent validated ledger is: 2025-04-22T14:40:00.000Z
|
||||
info: Credential is expired.
|
||||
```sh
|
||||
npm i
|
||||
```
|
||||
{% /tab %}
|
||||
|
||||
{% tab label="Unaccepted" %}
|
||||
```text
|
||||
$ ./verify_credential.js rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3 rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG Tst9Credential
|
||||
<!-- re-add Python tab when merging the tutorials
|
||||
{% tab label="Python" %}
|
||||
From the code sample folder, set up a virtual environment and use `pip` to install dependencies:
|
||||
|
||||
info: Encoded credential_type as hex: 5473743943726564656E7469616C
|
||||
info: Looking up credential...
|
||||
info: {
|
||||
"command": "ledger_entry",
|
||||
"credential": {
|
||||
"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
|
||||
"issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
|
||||
"credential_type": "5473743943726564656E7469616C"
|
||||
},
|
||||
"ledger_index": "validated"
|
||||
}
|
||||
info: Found credential:
|
||||
info: {
|
||||
"CredentialType": "5473743943726564656E7469616C",
|
||||
"Expiration": 797007605,
|
||||
"Flags": 0,
|
||||
"Issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
|
||||
"IssuerNode": "0",
|
||||
"LedgerEntryType": "Credential",
|
||||
"PreviousTxnID": "A7A5F2AF66222B7ECDBC005477BDDCE35E1460FC53339A7800CBDE79DBBB6FE4",
|
||||
"PreviousTxnLgrSeq": 1633091,
|
||||
"Subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
|
||||
"SubjectNode": "0",
|
||||
"URI": "746573745F757269",
|
||||
"index": "4282469903F9046C8E559447CB1B17A18362E2AFC04399BB7516EFB0B1413EAB"
|
||||
}
|
||||
info: Credential is not accepted.
|
||||
```sh
|
||||
python -m venv .venv
|
||||
source .venv/bin/activate
|
||||
pip install -r requirements.txt
|
||||
```
|
||||
{% /tab %}
|
||||
-->
|
||||
{% /tabs %}
|
||||
|
||||
{% tab label="Hexadecimal Credential Type" %}
|
||||
```text
|
||||
$ ./verify_credential.js rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3 rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG 5473743343726564656E7469616C -b
|
||||
### 2. Set up client and define constants
|
||||
|
||||
info: Looking up credential...
|
||||
info: {
|
||||
"command": "ledger_entry",
|
||||
"credential": {
|
||||
"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
|
||||
"issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
|
||||
"credential_type": "5473743343726564656E7469616C"
|
||||
},
|
||||
"ledger_index": "validated"
|
||||
}
|
||||
info: Found credential:
|
||||
info: {
|
||||
"CredentialType": "5473743343726564656E7469616C",
|
||||
"Flags": 65536,
|
||||
"Issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
|
||||
"IssuerNode": "0",
|
||||
"LedgerEntryType": "Credential",
|
||||
"PreviousTxnID": "062DA0586A57A32220785159D98F5206A14C4B98F5A7D8A9BCDB6836E33C45FE",
|
||||
"PreviousTxnLgrSeq": 1768019,
|
||||
"Subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
|
||||
"SubjectNode": "0",
|
||||
"URI": "746573745F757269",
|
||||
"index": "8548D8DC544153044D17E38499F8CB4E00E40A93085FD979AB8B949806668843"
|
||||
}
|
||||
info: Credential is valid.
|
||||
```
|
||||
To get started, import the client library and instantiate an API client. You also need to specify the details of the credential you want to verify.
|
||||
|
||||
{% tabs %}
|
||||
{% tab label="JavaScript" %}
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" before="// Look up Credential" /%}
|
||||
{% /tab %}
|
||||
{% /tabs %}
|
||||
|
||||
### 3. Look up the credential
|
||||
|
||||
## Code Walkthrough
|
||||
Use the [ledger_entry method][] to request the credential, using the latest validated ledger version. The response includes the [Credential entry][] as it is stored in the ledger.
|
||||
|
||||
### 1. Initial setup
|
||||
If the request fails with an `entryNotFound` error, then the specified credential doesn't exist in the ledger. This could mean you got one of the values wrong or the credential has been deleted.
|
||||
|
||||
The `verify_credential.js` file implements the code for this tutorial.
|
||||
This file can be run as a commandline tool, so it starts with a [shebang](https://en.wikipedia.org/wiki/Shebang_(Unix)). Then it imports the relevant dependencies, including the specific parts of the `xrpl.js` library:
|
||||
{% tabs %}
|
||||
{% tab label="JavaScript" %}
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Look up Credential" before="// Check if the credential has been accepted" /%}
|
||||
{% /tab %}
|
||||
{% /tabs %}
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" before="// Set up logging" /%}
|
||||
### 4. Check if the credential has been accepted
|
||||
|
||||
The next section of the code sets the default log level for messages that might be written to the console through the utility:
|
||||
Since a credential isn't valid until the subject has accepted it, you need to check if the credential has been accepted to know if it's valid. The accepted status of a credential is stored as a flag in the `Flags` field, so you use the bitwise-AND operator to see if that particular flag is enabled.
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Set up logging" before="// Define an error to throw" /%}
|
||||
{% tabs %}
|
||||
{% tab label="JavaScript" %}
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Check if the credential has been accepted" before="// Confirm that the credential is not expired" /%}
|
||||
{% /tab %}
|
||||
{% /tabs %}
|
||||
|
||||
Then it defines a type of exception to throw if something goes wrong when connecting to the XRP Ledger:
|
||||
### 5. Check credential expiration
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Define an error to throw" before="const CREDENTIAL" /%}
|
||||
If the credential has an expiration time, you need to confirm that it has not passed, causing the credential to expire. As with all expirations in the XRP Ledger, expiration is compared with the official close time of the previous ledger, so use the [ledger method][] to fetch the ledger header and compare against the close time.
|
||||
|
||||
Finally, a regular expression to validate the credential format and the [lsfAccepted](../../../references/protocol/ledger-data/ledger-entry-types/credential.md#credential-flags) flag are defined as constants for use further on in the code.
|
||||
If the credential does not have an expiration time, then it remains valid indefinitely.
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="const CREDENTIAL" before="async function verifyCredential" /%}
|
||||
{% tabs %}
|
||||
{% tab label="JavaScript" %}
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Confirm that the credential is not expired" before="// Credential has passed" /%}
|
||||
{% /tab %}
|
||||
{% /tabs %}
|
||||
|
||||
### 2. verifyCredential function
|
||||
### 6. Declare credential valid
|
||||
|
||||
The `verifyCredential(...)` function performs the main work for this tutorial. The function definition and comments define the parameters:
|
||||
If the credential has passed all checks to this point, it is valid. In summary, the checks were:
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="async function verifyCredential" before="// Encode credentialType as uppercase hex" /%}
|
||||
- The credential exists in the latest validated ledger.
|
||||
- It has been accepted by the subject.
|
||||
- It has not expired.
|
||||
|
||||
The XRP Ledger APIs require the credential type to be hexadecimal, so it converts the user input if necessary:
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Encode credentialType as uppercase hex" before="// Perform XRPL lookup" /%}
|
||||
|
||||
Next, it calls the [ledger_entry method](/docs/references/http-websocket-apis/public-api-methods/ledger-methods/ledger_entry#get-credential-entry) to look up the requested Credential ledger entry:
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Perform XRPL lookup" before="// Check if the credential has been accepted" /%}
|
||||
|
||||
If it succeeds in finding the credential, the function continues by checking that the credential has been accepted by its holder. Since anyone can issue a credential to anyone else, a credential is only considered valid if its subject has accepted it.
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="Check if the credential has been accepted" before="// Confirm that the credential is not expired" /%}
|
||||
|
||||
Then, if the credential has an expiration time, the function checks that the credential is not expired. If the credential has no expiration, this step can be skipped. A credential is officially considered expired if its expiration time is before the [official close time](/docs/concepts/ledgers/ledger-close-times) of the most recently validated ledger. This is more universal than comparing the expiration to your own local clock. Thus, the code uses the [ledger method][] to look up the most recently validated ledger:
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Confirm that the credential is not expired" before="// Credential has passed all checks" /%}
|
||||
|
||||
If none of the checks up to this point have returned a `false` value, then the credential must be valid. This concludes the `verifyCredential(...)` function:
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Credential has passed all checks" before="// Commandline usage" /%}
|
||||
|
||||
### 3. Commandline interface
|
||||
|
||||
This file also implements a commandline utility which runs when the file is executed directly as a Node.js script. Some variables, such as the set of available networks, are only needed for this mode:
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Commandline usage" before="// Parse arguments" /%}
|
||||
|
||||
Then it uses the [commander package](https://www.npmjs.com/package/commander) to define and parse the arguments that the user can pass from the commandline:
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Parse arguments" before="// Call verify_credential" /%}
|
||||
|
||||
After parsing the commandline args, it sets the appropriate values and passes them to `verifyCredential(...)` to perform the credential verification:
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Call verify_credential" before="// Return a nonzero exit code" /%}
|
||||
|
||||
It returns a nonzero exit code if this credential was not verified. This can be useful for shell scripts:
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Return a nonzero exit code" before="main().catch" /%}
|
||||
|
||||
Finally, the code runs the `main()` function:
|
||||
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="main().catch" /%}
|
||||
{% tabs %}
|
||||
{% tab label="JavaScript" %}
|
||||
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Credential has passed" /%}
|
||||
{% /tab %}
|
||||
{% /tabs %}
|
||||
|
||||
|
||||
## Next Steps
|
||||
@@ -316,5 +127,11 @@ Now that you know how to use `xrpl.js` to verify credentials, you can try buildi
|
||||
## See Also
|
||||
|
||||
- [Verify Credentials in Python](../../python/compliance/verify-credential.md)
|
||||
- **References:**
|
||||
- API methods:
|
||||
- [ledger_entry method][]
|
||||
- [ledger method][]
|
||||
- Ledger entries:
|
||||
- [Credential entry][]
|
||||
|
||||
{% raw-partial file="/docs/_snippets/common-links.md" /%}
|
||||
|
||||
Reference in New Issue
Block a user