setting og image in next.js 13: Typescript error: 'string | undefined' is not assignable to type 'OGImage'

Setting OG Image in Next.js 13: Typescript Error: ‘string | undefined’ is not assignable to type ‘OGImage’

If you are working with Next.js 13 and TypeScript, you might come across the following error when trying to set the OG (Open Graph) image for your website:

'string | undefined' is not assignable to type 'OGImage'

This error occurs because the type definition for the OG image in Next.js 13 expects a specific type, but the value you are passing is of type ‘string | undefined’. To resolve this issue, you have a few options:

Solution 1: Use Non-Nullable Assertion Operator

One way to fix this error is by using the non-nullable assertion operator (!) to tell TypeScript that the value will not be undefined. Here’s an example:

        
            import { NextSeo } from 'next-seo';

            const ogImageUrl: string | undefined = 'https://example.com/og-image.jpg';

            const ogImage: OGImage = ogImageUrl!;

            const MyPage = () => {
                return (
                    
                        
                        
                    
                );
            };

            export default MyPage;

In this solution, we use the non-nullable assertion operator (!) to assert that the value of ogImageUrl will not be undefined. However, be cautious when using this operator, as it can lead to runtime errors if the value is actually undefined at runtime.

Solution 2: Use Optional Chaining Operator

Another approach is to use the optional chaining operator (?) to handle the case when the value is undefined. Here’s an example:

        
            import { NextSeo } from 'next-seo';

            const ogImageUrl: string | undefined = 'https://example.com/og-image.jpg';

            const ogImage: OGImage = ogImageUrl ?? undefined;

            const MyPage = () => {
                return (
                    
                        
                        
                    
                );
            };

            export default MyPage;

In this solution, we use the nullish coalescing operator (??) to provide a fallback value of undefined when ogImageUrl is undefined. This ensures that the type of ogImage is ‘OGImage’ as expected by Next.js 13.

Solution 3: Use Type Assertion

If you are certain that the value will never be undefined, you can use a type assertion to explicitly tell TypeScript the type of the value. Here’s an example:

        
            import { NextSeo } from 'next-seo';

            const ogImageUrl: string | undefined = 'https://example.com/og-image.jpg';

            const ogImage: OGImage = ogImageUrl as OGImage;

            const MyPage = () => {
                return (
                    
                        
                        
                    
                );
            };

            export default MyPage;

In this solution, we use a type assertion (as OGImage) to explicitly tell TypeScript that the value of ogImageUrl is of type ‘OGImage’. However, make sure you are confident in the type of the value to avoid runtime errors.

By using one of these solutions, you should be able to resolve the TypeScript error and set the OG image for your Next.js 13 application without any issues.

setting og image in next.js 13: Typescript error: ‘string | undefined’ is not assignable to type ‘OGImage’