Part 2: Call a Jira API

This page introduces the Forge Javascript APIs. Using the @forge/api package, you'll learn how to make REST calls to an authenticated Jira endpoint.

This is part 2 of 3 in this tutorial. Complete Part 1: Build a Jira hello world app before working on this page.

Make an API call

In this section, you'll modify your app to call the Jira REST API. Using the Product Fetch API from the @forge/api package, you'll get the comments on a Jira issue in the form of an array and print the number of comments to the console.

The @forge/api package simplifies HTTP operations and contains other Forge APIs such as the Storage and Properties APIs. For this tutorial, you'll also use a UI kit hook to get context information about the Jira issue the app is on.

In the app’s top-level directory, install the @forge/api package API by running:
```
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npm install @forge/api
```
Restart your tunnel to use the new npm modules by running:
```
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forge tunnel
```
Make sure your docker is running.

Navigate to the src directory and open the index.jsx file. Import the @forge/api package by adding the following to the top of the file:

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import api, { route } from "@forge/api";

Copy the following code to create a function that calls the Jira REST API by using the @forge/api package:

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const fetchCommentsForIssue = async (issueIdOrKey) => {
  const res = await api
    .asUser()
    .requestJira(route`/rest/api/3/issue/${issueIdOrKey}/comment`);

  const data = await res.json();
  return data.comments;
};

This function takes an issueIdOrKey to call the REST API with path /rest/api/3/issue/${issueIdOrKey}/comment.

Use the UI kit hook useProductContext to get the issueId to call fetchCommentsForIssue:

Add useProductContext to the import statement as shown below:

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import ForgeUI, { render, Fragment, Text, IssuePanel, useProductContext } from "@forge/ui";

Add the following code to the App function directly before the return statement:

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const context = useProductContext();

Fetch the comments for the page and log the output in the App function.

Add the useState UI kit hook to the import statement as shown below:

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import ForgeUI, { render, Fragment, Text, IssuePanel, useProductContext, useState } from "@forge/ui";

Add the following code to the App function directly above the return statement:

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const [comments] = useState(async () => await fetchCommentsForIssue(context.platformContext.issueKey));

console.log(`Number of comments on this issue: ${comments.length}`);

When you save the index.jsx file, the tunnel output in the terminal will display a permission-scope-required error. To address this, you'll need to add the required permissions first; this is covered in the next section.

Your index.jsx file should look like the following:

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import api, { route } from "@forge/api";
import ForgeUI, { render, Fragment, Text, IssuePanel, useProductContext, useState } from "@forge/ui";

const fetchCommentsForIssue = async (issueIdOrKey) => {
  const res = await api
    .asUser()
    .requestJira(route`/rest/api/3/issue/${issueIdOrKey}/comment`);

  const data = await res.json();
  return data.comments;
};

const App = () => {
  const context = useProductContext();
  const [comments] = useState(async () => await fetchCommentsForIssue(context.platformContext.issueKey));

  console.log(`Number of comments on this issue: ${comments.length}`);

  return (
    <Fragment>
      <Text>Hello world!</Text>
    </Fragment>
  );
};

export const run = render(
  <IssuePanel>
    <App />
  </IssuePanel>
);

Set required permissions

Your app calls a remote resource; namely, the Jira REST API. As such, you'll need to grant your app the right permissions. To do this, you'll need to add the required OAuth 2.0 scope to the app's manifest.

For more information on adding scopes, see Add scopes to call an Atlassian REST API.

In the steps below, you'll do this by using the forge lint command. This command will automatically add the required scope to your manifest.yml file (in this case, read:jira-work).

Run the following command:

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forge lint --fix

Whenever you change permissions, you must upgrade the app's installation. Stop your tunnel process and run these commands to deploy and install your change:
```
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forge deploy
forge install --upgrade
```
Start the tunnel again:
```
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forge tunnel
```

Alternatively, you can also manually add required scopes to your manifest.yml file. Learn more about adding scopes to call an Atlassian REST API.

Test your app

Create a new Jira issue, or open the one you created earlier.
Add a comment to the Jira issue. For example, a comment with Hello from the comments.
Refresh the Jira issue view. Note, you'll need to authorize the app to display it again, as the scopes have changed. Follow the onscreen prompts to allow the app to access Atlassian products on your behalf.

Check the output of the tunnel in the terminal. The number of comments on the issue displays as follows:

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invocation: 158b5987a4724ee5 index.run
INFO  05:01:33.408  158b5987a4724ee5  Number of comments on this issue: 1

The .asUser() function inherits the product permissions of the user who has granted access to the app. This can cause different API responses between different users in the same app.

Next step

In the next tutorial, you'll learn how to make changes to your app's frontend using the UI kit components of Forge.