Build an Image Gallery in Next.js with Headless Oracle Content Management

Introduction

Next.js is an open-source React front-end development web framework that enables functionality such as server-side rendering and generating static websites for React based web applications.

This tutorial will introduce you to the basic steps of building an image viewer using Next.js, with Oracle Content Management as the content management system and its Content SDK. You’ll see how taxonomies can be used to categorize content and how different renditions of digital assets can be used for various use cases. This Next.js sample is available on GitHub.

The tutorial consists of three tasks:

Prepare Oracle Content Management
Build the Image Gallery in Next.js
Prepare your application for deployment

Prerequisites

Before proceeding with this tutorial, we recommend that you read the following information first:

To follow this tutorial, you’ll need:

an Oracle Content Management subscription
an Oracle Content Management account with the Content Administrator role
a Windows or Mac computer with Node version 10 or higher

What We’re Building

Our image gallery will consist of several pages of images of food and drinks available at a coffee shop.

This image shows an image gallery with different kinds of bagels, some with cream or toppings, or both.

To take a look at what we’re building, here is the end state of our tutorial, a live version of this image gallery site:

https://headless.mycontentdemo.com/samples/oce-nextjs-gallery-sample

Categories are child nodes of a taxonomy and can be organized into hierarchies. For our image gallery, we want to show all available categories regardless of the organization. To accomplish this, we first need to find the available taxonomies, which we do using the Content SDK’s getTaxonomies() method.

Note: The implementation of getTaxonomies uses the REST API resource GET /published/api/v1.1/taxonomies.

Next, we need to get the set of categories for each of the taxonomies. This is done using the Content SDK’s queryTaxonomyCategories() method.

Note: The implementation of queryTaxonomyCategories uses the REST API GET /published/api/v1.1/taxonomies/{id}/categories.

To build the preview of a category, such as Bagels, we need to get a count of the number of images and the URLs of the first four images.

This image shows images in the Bagels category.

Our request to find the published assets in the category specifies the category criteria through a query string, as follows:

"(taxonomies.categories.nodes.id eq 892CD6BC4F654249A00CB7942EE8C773)"

To optimize the image loading, we’ll use a rendition of the image named ‘Thumbnail’. See retrieveThumbnailURL(), in scripts/services.js, for the code that examines the set of available renditions for each image.

Note: In addition to publishing the digital assets that we want to view, you also need to publish the taxonomies to the channel.

To proceed, you’ll need to have an active subscription to Oracle Content Management and be logged in with the Content Administrator role.

Task 1: Prepare Oracle Content Management

This tutorial is based on the assumption that you’ve created your asset repository and currently have an empty content model (that is, no content types created).

If you don’t already have an Oracle Content Management instance, see the Quick Start to learn how to register for Oracle Cloud, provision an Oracle Content Management instance, and configure Oracle Content Management as a headless CMS.

For this tutorial, you’ll need to create a content model in either of two ways. There’s a downloadable asset pack available that will fill your empty repository with content types and associated content, or you can create your own content model and content.

To prepare Oracle Content Management:

Create a channel and asset repository.
Import the Oracle Content Management Samples Asset Pack
Upload Your Own Image Assets
Create Taxonomies and Link Them to Image Assets

Create a Channel and Asset Repository

You first need to create a channel and an asset repository in Oracle Content Management so you can publish content.

To create a channel and an asset repository in Oracle Content Management:

Log in to the Oracle Content Management web interface as an administrator.
Choose Content in the left navigation menu and then choose Publishing Channels from the selection list in the page header.
In the upper right corner, click Create to create a new channel. Name the channel ‘OCEImageGalleryChannel’ for the purpose of this tutorial, and keep the access public. Click Save to create the channel.
Choose Content in the left navigation menu and then choose Repositories from the selection list in the page header.
In the upper right corner, click Create to create a new asset repository. Name the asset repository ‘OCEImageGalleryRepository’ for the purpose of this tutorial.
In the Publishing Channels field, select OCEImageGalleryChannel to indicate to Oracle Content Management that content in the OCEImageGalleryRepository repository can be published to the OCEImageGalleryChannel channel. Click Save when you’re done.

Import the Oracle Content Management Samples Asset Pack

You can download a preconfigured Oracle Content Management sample assets pack that contains all required content types and assets for this tutorial.

You can upload a copy of the content we’re using in this tutorial from the Oracle Content Management Samples Asset Pack. This will let you experiment with the content types and modify the content. You can download the asset pack archive, OCESamplesAssetPack.zip, and extract it to a directory of your choice:

Download the Oracle Content Management Samples Asset Pack (OCESamplesAssetPack.zip) from the Oracle Content Management downloads page. Extract the downloaded zip file to a location on your computer. After extraction, this location will include a file called OCEImageGallery_data.zip.
Log in to the Oracle Content Management web interface as an administrator.
Choose Content in the left navigation menu and then choose Repositories from the selection list in the page header. Now select OCEImageGalleryRepository and click the Import Content button in the top action bar.
Upload OCEImageGallery_data.zip from your local computer to the Documents folder.
Once it’s uploaded, select OCEImageGallery_data.zip and click OK to import the contents into your asset repository.
After the content has been imported successfully, navigate to the Assets page and open the OCEImageGalleryRepository repository. You’ll see that all the related images and content items have now been added to the asset repository.
Click Select All on the top left and then Publish to add all the imported assets to the publishing channel that you created earlier, OCEImageGalleryChannel.
Before publishing, you need to validate all the assets. First add OCEImageGalleryChannel as a selected channel, and then click the Validate button.
After the assets have been validated, you can publish all the assets to the selected channel by clicking the Publish button in the top right corner.

Once that’s done, you can see on the Assets page that all assets have been published. (You can tell by the icon above the asset name.)

This image shows the Assets page, with all assets pubished.

After importing the Oracle Content Management Samples Asset Pack, you can start building the image gallery in Next.js.

Upload Your Own Image Assets

For this tutorial, we’re using an asset repository called ‘OCEImageGalleryRepository’ to build the home page for our gallery site. This home page consists of the title ‘Image Gallery’ as well as image collection albums that have image assets inside.

This image shows the home page for the image gallery, with images of various image categories: sandwiches, drinks, dessert, breakfast, and food.

To add image assets to the gallery asset repository:

Log in to the Oracle Content Management web interface.
Click Assets in the left navigation menu.
Open the OCEImageGalleryRepository repository.
Click Add in the upper right corner of the page to add image assets to the gallery asset repository.
Upload your own new assets from your local computer or choose existing assets already in Oracle Content Management.

Create Taxonomies and Link Them to Image Assets

You need to create a taxonomy in Oracle Content Management and then assign categories to the assets in your repository.

To create a taxonomy in Oracle Content Management:

Log in to the Oracle Content Management web interface as an administrator.
Choose Content in the left navigation menu and then choose Taxonomies from the selection list in the page header.
In the upper right corner, click Create to create a new taxonomy. Name the channel ‘OCEImageGalleryTaxonomy’ for the purpose of this tutorial.
Click Create.
Now build your taxonomy by adding categories. Click Add a category.
Name the parent category item ‘Food’, and add the following child categories:
- Breakfast
- Dessert
- Drinks
- Sandwiches
Click Done at the top right of the screen.
On the Taxonomies page, select the OCEImageGalleryTaxonomy taxonomy and click Promote in the actions bar to make it available for use in your asset repositories.

Next, edit the OCEImageGalleryRepository repository to enable the OCEImageGalleryTaxonomy taxonomy for that repository:

Log in to the Oracle Content Management web interface as an administrator.
Choose Content in the left navigation menu and then choose Repositories from the selection list in the page header.
Select and edit the OCEImageGalleryRepository repository.
In the Taxonomies field, select OCEImageGalleryTaxonomy, so you can assign categories from that taxonomy to the assets in the OCEImageGalleryRepository repository.
Click Save.

Then, assign taxonomy categories to each of the image assets in the OCEImageGalleryRepository repository:

Log in to the Oracle Content Management web interface.
Click Assets in the left navigation menu.
Open the OCEImageGalleryRepository repository.
Select one or more image assets, click More in the actions bar, and then choose Categories from the menu.
In the Categories panel, click Add Category. Search for the category name in the search bar or select a category from the taxonomy hierarchical structure, and click Add to assign the selected category. You can assign multiple categories to an asset.
After you’re done assigning taxonomies to all the image assets, select all assets in your repository and publish them to the OCEImageGalleryChannel channel.

Task 2: Build the Image Gallery in Next.js

To consume our Oracle Content Management content in a Next.js application, we can use the Next.js image gallery sample, which is available as an open-source repository on GitHub.

Note: Remember that using the Next.js sample is optional, and we use it in this tutorial to get you started quickly. You can also build your own Next.js application.

To build the image gallery in Next.js:

Clone the sample repository and install dependencies
Configure the Next.js application
Work with the Oracle Content Management Content SDK
Use the Content SDK to Fetch Content

Clone the Sample Repository and Install Dependencies

The Next.js blog sample is available as an open-source repository on GitHub.

You’ll first need to clone the sample from GitHub to your local computer and change your directory into the repository root:

git clone https://github.com/oracle/oce-nextjs-gallery-sample.git
    cd oce-nextjs-gallery-sample

Now that you have your code base, you need to download dependencies for the application. Run the following command from the root directory:

npm install

Configure the Next.js Application

In this Next.js image gallery sample, you need to configure a few pieces of information so that your Oracle Content Management Content SDK (and any other requests) can target the correct instance URL and API version with the correct channel token. These values are used in scripts/server-config-utils.js to instantiate a new delivery client.

This application uses an .env.local file which is read by Next.js and made available to the code inside the application with process.env.

Open the .env.local file in a text editor. You’ll see the following information:

# The connection details for the Oracle Content Management server to be used for this application
    SERVER_URL=https://samples.mycontentdemo.com
    API_VERSION=v1.1
    CHANNEL_TOKEN=e0b6421e73454818948de7b1eaddb091

Change each key-value pair to reflect your instance URL, the API version you want to target, and the channel token associated with your publishing channel. The channel for this tutorial is OCEImageGalleryChannel.

Work with the Oracle Content Management Content SDK

Oracle Content Management offers an SDK to help discover and use content in your applications. The SDK is published as an NPM module, and the project is hosted on GitHub.

Learn more about the SDK here.

The SDK has been registered as a runtime dependency of this project in the package.json file.

Use the Content SDK to Fetch Content

We can now leverage the Content SDK to fetch content so that we can render it in our Next.js application.

The scripts folder contains the code for getting data from Oracle Content Management using the Content SDK.

The scripts/server-config-utils.js file imports the Content SDK and then creates a delivery client using the configuration specified in .env.local.

The following command imports the SDK:

import { createDeliveryClient, createPreviewClient } from '@oracle/content-management-sdk';

The following command creates the delivery client:

return createDeliveryClient(serverconfig);

The scripts/services.js file contains all the code to get data for the application. There’s one main function for each page component in the application to get all the data for that page.

For rendering the images, the services.js provides a helper method to retrieve the sourceset for an asset that is constructed from the renditions for the asset.

function getSourceSet(asset) {
      const urls = {};
      urls.srcset = '';
      urls.jpgSrcset = '';
      if (asset.fields && asset.fields.renditions) {
        asset.fields.renditions.forEach((rendition) => {
          addRendition(urls, rendition, 'jpg');
          addRendition(urls, rendition, 'webp');
        });
      }
      // add the native rendition to the srcset as well
      urls.srcset += `${asset.fields.native.links[0].href} ${asset.fields.metadata.width}w`;
      urls.native = asset.fields.native.links[0].href;
      urls.width = asset.fields.metadata.width;
      urls.height = asset.fields.metadata.height;
      return urls;
    }

Home Page Data

The home page requires several data calls to get all of its data:

First we load the taxonomies for the channel specified in .env.
For each of the taxonomies, we get all the categories in that taxonomy.
For each category, we get four content items in that category.
For each of those items, we get its rendition URLs.

Open src/scripts/services.js and find the getHomePageData() function, which is used to get all of the data for the home page.

export function getHomePageData() {
      const deliveryClient = getClient();
      // get the categories for all taxonomies then add all the category items to each category
      return fetchAllTaxonomiesCategories(deliveryClient).then(
        (initialCategories) => addItemsToCategories(deliveryClient, initialCategories).then(
          (categories) => {
            // pull out all of the items for all of the categories then
            // append the computed renditionUrls to each item.
            const allItems = categories.map((category) => category.items);
            const items = flattenArray(allItems);
            // for each item, retrieve the rendition urls and add it to the item
            items.forEach((item) => {
              item.renditionUrls = getSourceSet(item);
            });
            return { categories };
          },
        ),
      );
    }

getHomePageData() calls fetchAllTaxonomiesCategories() to get all the categories in all of the taxonomies.

export function fetchAllTaxonomiesCategories(client) {
      return client
        .getTaxonomies()
        .then((topLevelItem) => {
          const taxonomyIds = topLevelItem.items.map((taxonomy) => taxonomy.id);
    
          const promises = [];
          // loop over each taxonomy id
          taxonomyIds.forEach((taxonomyId) => {
            // add a promise to the total list of promises to get the categories
            // for the specific taxonomy id
            promises.push(
              fetchCategoriesForTaxonomyId(client, taxonomyId)
                .then((categoriesTopItem) => categoriesTopItem.items),
            );
          });
    
          // execute all the promises returning a single dimension array of all
          // of the categories for all of the taxonomies (note: no taxonomy information)
          // is returned.
          return Promise.all(promises)
            .then((arrayOfCategoryArray) => flattenArray(arrayOfCategoryArray));
        })
        .catch((error) => logError('Fetching taxonomies failed', error));
    }

fetchAllTaxonomiesCategories() calls fetchCategoriesForTaxonomyId() to get all the categories in a specific taxonomy.

function fetchCategoriesForTaxonomyId(client, taxonomyId) {
      return client
        .queryTaxonomyCategories({
          id: `${taxonomyId}`,
        })
        .then((topLevelItem) => topLevelItem)
        .catch((error) => logError('Fetching categories for taxonomy failed', error));
    }

The addItemsToCategories function is then called to add the four category items to each category.

function addItemsToCategories(client, categories) {
      const promises = [];
    
      // loop over each category
      categories.forEach((category) => {
        // add a promise to the total list of promises to get the items
        // for the specific category
        promises.push(
          fetchItemsForCategory(client, category.id, true).then(
            (topLevelItem) => {
              // add the item to the category before returning it
              category.items = topLevelItem.items;
              category.totalResults = topLevelItem.totalResults;
              return {
                ...category,
              };
            },
          ),
        );
      });
    
      // execute all the promises before returning the data
      return Promise.all(promises).then((arrayOfItems) => flattenArray(arrayOfItems));
    }

Finally, getSourceSet seen previously is called to get the rendition URLs for each item.

Image Grid Page Data

The image grid page receives a category ID and requires several data calls to get all of its data:

Get all the items for the specified category.
For each item, get its rendition URLs.

Open src/scripts/services.js and find the getImageGridPageData() function, which is used to get all of the data for the image grid page.

export function getImageGridPageData(categoryId) {
      const client = getClient();
    
      return fetchItemsForCategory(client, categoryId, false).then(
        (topLevelItem) => {
          const { totalResults } = topLevelItem;
          // for each item, retrieve the rendition urls and add it to the item
          topLevelItem.items.forEach((item) => {
            item.renditionUrls = getSourceSet(item);
          });
          return {
            totalResults,
            items: topLevelItem.items,
          };
        },
      );
    }

It calls fetchItemsForCategory, like the home page, but with no limit, so that all the items are returned, not just four.

Now that we have our data queries, we can render the responses in our Next.js components.

Next.js Components

Next.js is based on React and React uses a technology known as JSX, which is an HTML-like syntax extension to JavaScript, to render content. Even though you can write pure JavaScript to render data from Oracle Content Management, we strongly recommend that you use JSX.

The image gallery application breaks down each page into a number of smaller components, some of which are used in both the home and image grid pages.

The next few sections provide an overview of how Next.js renders our application in each of our components:

Pages Folder
Index Component
Gallery Component
ImageGridPage Component

Pages Folder

In our site, we want to provide two routes:

The home page, which shows a list of image categories
The image grid page, which displays all the items for a given category id

Any page in the pages directory Next.js will treat as a route for the application.

Index Component

The home page consists of a list of categories for a taxonomy, with a preview of four items in that category. It is rendered by the Index component, located at pages/index.jsx.

The component imports the API to get data from the services.js file.

import { getHomePageData } from '../scripts/services';

In getStaticProps(), called during build time, the component gets all the data required to render the home page.

export async function getStaticProps() {
      const data = await getHomePageData();
      return {
        props: { data },
      };
    }

Gallery Component

The Gallery component represents the individual category in the list. It displays a preview of four of the items in the category.

It is located at src/components/Gallery.jsx and receives all of its data as properties. It does not get any additional data from the server.

ImageGridPage Component

The Image Grid Page component displays the items in the category whose ID is passed into the component on the URL. It is rendered by the ArticleListPage component, located at pages/category/[id].jsx.

The component imports the API to get data from the services.js file.

import { fetchAllTaxonomiesCategories, getImageGridPageData } from '../../scripts/services';

The URLs for the Image Grid Page are dynamic URLs containing the category id and name as a path, example URL paths are

/category/categoryId1-name1
/category/categoryId2-name2
/category/categoryId3-name3

When Next.js uses static site generation for pages with dynamic URLs it calls getStaticPaths() to get all the paths for that page.

export async function getStaticPaths() {
      const categories = await fetchAllTaxonomiesCategories();
      return {
        paths: categories.map((category) => ({
          params: { id: `${category.id}-${category.name}` },
        })),
        fallback: true,
      };
    }

The getStaticProps() function is used to get the data for a single instance of the Image Grid page. The category id and name are obtained from the parameter passed into the method. The category id is then used to get all the data required for this page.

export async function getStaticProps(context) {
      const { params } = context;
    
      const { id } = params;
      const arr = id.split('-');
      const categoryName = arr[1];
      const categoryId = arr[0];
      const data = await getImageGridPageData(categoryId);
      return {
        props: {
          data,
          categoryName,
        },
      };
    }

Task 3: Prepare Your Application for Deployment

Now that we’ve built our Next.js blog site, we need to see it in a local development server so we can debug any issues and preview the application before it goes live.

Prepare the application for deployment in two steps:

Spin up a local development server
Use scripts to build and run the application in development and production

Spin Up a Local Development Server

You can start a development server locally by running the following command.

npm run dev

Then, open your browser to http://localhost:3000 to see your site in action.

Note: This will not pre-render the pages, in order to pre-render the pages, see the next section.

Use Scripts to Build and Run the Application in Development and Production

For production, the build script would be used to statically generate the site.

npm run build

The start script is used to start a Node.js server serving the statically generated pages.

npm run start

Title and Copyright Information

Build an Image Gallery in Next.js with Headless Oracle Content Management

F39696-01

October 2021

Primary Author: Oracle Corporation