I have a microservice architecture where I am trying to call other service via exchange method to get list of users profiles.

@Override
    public List<Profile> getListOfProfile(List<String> receiverId) {
        ListOfProfileDto listOfProfileDto = new ListOfProfileDto();
        listOfProfileDto.setId(receiverId);
        HttpHeaders httpHeaders = new HttpHeaders();
        httpHeaders.setContentType(MediaType.APPLICATION_JSON);
        HttpEntity<Object> requestEntity = new HttpEntity<>(listOfProfileDto, httpHeaders);
        try {
            Object foundProfile = restTemplate.exchange(
                    "http://localhost:8087/profile-service/profile/list",
                    HttpMethod.POST,
                    requestEntity,
                    Object.class
            ).getBody();
            return (List<Profile>) foundProfile;

        } 
    }

When I get that list in other part of code I am trying to iterate it.

  receiversProfiles.forEach(rp -> {
            var invitedFriend = InvitedFriends.builder()
                    .firstName(rp.getFirstName())
                    .lastName(rp.getLastName())
                    .build();
            invitedFriendsList.add(invitedFriend);
        });

And here is where I am getting following error:

{
    "status": 500,
    "timeStamp": "15/05/2022 15:35:27",
    "message": "class java.util.LinkedHashMap cannot be cast to class com.profile.model.Profile (java.util.LinkedHashMap is in module java.base of loader 'bootstrap'; com.profile.model.Profile is in unnamed module of loader 'app')",
    "details": "uri=/profile/save"
}

When I am getting response from my other service I am seeing this:

Where found profile is a hashmap that I am trying to convert to List<Profile> but not able to.

and in this piece of code when I am trying to iterate

receiversProfiles.forEach(rp -> {
            var invitedFriend = InvitedFriends.builder()
                    .firstName(rp.getFirstName())
                    .lastName(rp.getLastName())
                    .build();
            invitedFriendsList.add(invitedFriend);
        });

I guess I am trying to iterate trough hashmap as I am iterating trough list and this is why my code is braking.

How can I fix this?

CodePudding user response：

 List<Profile> foundProfile = restTemplate.exchange(
              "http://localhost:8087/profile-service/profile/list",
               HttpMethod.POST,
               requestEntity,
               new ParameterizedTypeReference<List<Profile>>() {}
).getBody();

Try this to cast to List of Profile upon executing request.

CodePudding user response：

When Jackson attempts to deserialize an object in JSON, but no target type information is given, it'll use the default type: LinkedHashMap.

Jackson: java.util.LinkedHashMap cannot be cast to X