apollographql/apollo-client @apollo/client@4.0.0-rc.7 on GitHub

Major Changes

#12809 e2a0be8 Thanks @jerelmiller! - operation.getContext now returns a Readonly<OperationContext> type.
#12809 e2a0be8 Thanks @jerelmiller! - The ApolloLink.Request (i.e. GraphQLRequest) passed to ApolloLink.execute no longer accepts operationName and operationType options. These properties are derived from the query and set on the returned ApolloLink.Operation type.
#12808 8e31a23 Thanks @phryneas! - HTTP Multipart handling will now throw an error if the connection closed before the final boundary has been received.
Data after the final boundary will be ignored.
#12809 e2a0be8 Thanks @jerelmiller! - operation.operationType is now a non-null OperationTypeNode. It is now safe to compare this value without having to check for undefined.
#12809 e2a0be8 Thanks @jerelmiller! - operation.operationName is now set as string | undefined where undefined represents an anonymous query. Previously operationName would return an empty string as the operationName for anonymous queries.
#12809 e2a0be8 Thanks @jerelmiller! - The concat, from, and split functions on ApollLink no longer support a plain request handler function. Please wrap the request handler with new ApolloLink.
```
const link = new ApolloLink(/* ... */);

link.concat(
- (operation, forward) => forward(operation),
+ new ApolloLink((operation, forward) => forward(operation)),
);
```
#12809 e2a0be8 Thanks @jerelmiller! - transformOperation and validateOperation have been removed and are no longer exported from @apollo/client/link/utils. These utilities have been merged into the implementation of createOperation. As a result, createOperation now returns a well-formed Operation object. Previously createOperation relied on an external call to transformOperation to provide a well-formed Operation type. If you use createOperation directly, remove the calls to transformOperation and validateOperation and pass the request directly.

#12809 e2a0be8 Thanks @jerelmiller! - The request handler provided to ApolloLink must now return an Observable. null is no longer supported as a valid return value. If you rely on null so that ApolloLink provides an empty observable, use the EMPTY observable from RxJS instead:

import { ApolloLink } from "@apollo/client";
+ import { EMPTY } from "rxjs";

const link = new ApolloLink((operation, forward) => {
- return null;
+ return EMPTY;
});

If you have a custom link that overrides the request method, remove null from the return signature:

class MyCustomLink extends ApolloLink {
  request(
    operation: ApolloLink.Operation,
    forward: ApolloLink.ForwardFunction,
- ): Observable<ApolloLink.Result> | null {
+ ): Observable<ApolloLink.Result> {
    // implementation
  }
}

#12809 e2a0be8 Thanks @jerelmiller! - createOperation no longer accepts context as the first argument. Instead make sure context is set as the context property on the request passed to createOperation.
```
createOperation(
- startingContext,
- { query },
+ { query, context: startingContext },
  { client }
);
```
#12809 e2a0be8 Thanks @jerelmiller! - Remove the TVariables generic argument on the GraphQLRequest type.
#12809 e2a0be8 Thanks @jerelmiller! - The context object returned from operation.getContext() is now frozen to prevent mutable changes to the object which could result in subtle bugs. This applies to the previousContext object passed to the operation.setContext() callback as well.
#12809 e2a0be8 Thanks @jerelmiller! - The forward function passed to the request handler is now always provided to request and no longer optional. If you create custom links by subclassing ApolloLink, the forward function no longer needs to be optional:
```
class CustomLink extends ApolloLink {
  request(
    operation: ApolloLink.Operation,
    // This no longer needs to be typed as optional
    forward: ApolloLink.ForwardFunction
  ) {
    // ...
  }
}
```
As a result of this change, ApolloLink no longer detects terminating links by checking function arity on the request handler. This means using methods such as concat on a terminating link no longer emit a warning. On the flip side, if the terminating link calls the forward function, a warning is emitted and an observable that immediately completes is returned which will result in an error from Apollo Client.

Minor Changes

#12809 e2a0be8 Thanks @jerelmiller! - ApolloLink's concat method now accepts multiple links to concatenate together.
```
const first = new ApolloLink();

const link = first.concat(second, third, fouth);
```
#12809 e2a0be8 Thanks @jerelmiller! - Many of the types exported from @apollo/client/link now live on the ApolloLink namespace. The old types are now deprecated in favor of the namespaced types.
- FetchResult -> ApolloLink.Result
- GraphQLRequest -> ApolloLink.Request
- NextLink -> ApolloLink.ForwardFunction
- Operation -> ApolloLink.Operation
- RequestHandler -> ApolloLink.RequestHandler
#12809 e2a0be8 Thanks @jerelmiller! - The static ApolloLink.concat method is now deprecated in favor of ApolloLink.from. ApolloLink.concat is now an alias for ApolloLink.from so prefer ApolloLink.from instead.

Patch Changes

#12809 e2a0be8 Thanks @jerelmiller! - The individual empty, concat, from and split functions exported from @apollo/client/link are now deprecated in favor of using the static functions instead.

import {
  ApolloLink,
- concat,
- empty,
- from,
- split,
} from "@apollo/client/link";

- concat(first, second);
+ ApolloLink.concat(first, second);

- empty();
+ ApolloLink.empty();

- from([first, second]);
+ ApolloLink.from([first, second]);

- split(
+ ApolloLink.split(
  (operation) => /* */,
  first,
  second
);