Malformed JSON: Expected '{' at the beginning of object?

Question

I searched all over but not found the right one.

My Body string below,

[{"revokePermSetNames":["RemovPerm1","RemovPerm2"],
  "EmployeeNumber":"8507",
  "assignPermSetNames":["AddPerm1","AddPerm2"]},
 {"revokePermSetNames":["RemovPerm3","RemovPerm4"],
  "EmployeeNumber":"8508",
  "assignPermSetNames":["AddPerm3","AddPerm4"]}]

My Class here

@HttpPost  
global static void processPermSetDelegation() {  
    System.debug('****'+RestContext.request);
    System.debug('^^^^'+RestContext.request.requestBody.toString());
    System.debug(String.valueOf(RestContext.request.params));

    List<permissionDataWrapper>  delegationMap = (List<permissionDataWrapper>)JSON.deserialize(RestContext.request.requestBody.toString(),permissionDataWrapper.class); 
    for(permissionDataWrapper cp : delegationMap) {
        System.debug('------'+cp.EmployeeNumber);
        for(string s: cp.assignPermSetNames )
            System.debug('Assign :------'+s);
        for(string a: cp.revokePermSetNames)
            System.debug('Revoke :------'+a);

        System.debug('------------------------------------------');
    }    
}

global class permissionDataWrapper {
    public String EmployeeNumber {get;set;}
    public Set<String> assignPermSetNames {get;set;}
    public Set<String> revokePermSetNames {get;set;}
    permissionDataWrapper () {
        assignPermSetNames = new Set<string>();
        revokePermSetNames = new Set<string>();
    }
}   

Error :

Malformed JSON: Expected '{' at the beginning of object

Answer 1

Try this ;)

List<permissionDataWrapper>  delegationMap = (List<permissionDataWrapper>)JSON.deserialize(RestContext.request.requestBody.toString(), List<permissionDataWrapper>.class);

You need to pass the List<permissionDataWrapper>.class not permissionDataWrapper.class for the 2nd parameter(JSON.deserialize(1st, 2nd)) because you are processing a list not a single item.