Resolving 'header.append is not a function' in Apollo Angular Authentication

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Understanding the Issue

Correct Way to Set Headers

To avoid this error, ensure you are using HttpHeaders properly when setting up the middleware for authentication. Here is a step-by-step example of how to correctly set up the authentication headers in Apollo Angular.

Step-by-Step Example

Install Apollo Angular and related dependencies:

[[See Video to Reveal this Text or Code Snippet]]

Set up Apollo Client:

[[See Video to Reveal this Text or Code Snippet]]

Provide the Apollo configuration in your module:

[[See Video to Reveal this Text or Code Snippet]]

Explanation

HttpLink: This creates the basic HTTP link for the Apollo client to connect to the GraphQL server.

setContext: This function is used to set the context for each request. Here, we're adding the Authorization header.

Common Pitfalls

Using Plain Objects: Ensure you're using HttpHeaders and not plain JavaScript objects for headers.

Token Retrieval: Make sure your token retrieval logic (e.g., from localStorage) is correct and secure.

Conclusion