I have the following WebGet:
    [WebGet(UriTemplate = "GetAssignments/{data}")]
    [Description("GetAssignments")]
    BASE.BaseResponse<object> GetAssignments(String data); 
Called thusly:
    var data = JSON.stringify(advancedSearchDataXml);
    Helper.Service.Call({
        api: 'HomeApi',
        url: '?method=GetAssignments/' + data,
        method: 'GET',
        //data: advancedSearchDataXml,
        controlId: '',
        showProgress: true,
        onSuccess: function (result) {
    ...
where data is
{"searchquery":
    "<SearchQuery>
        <genericsearch></genericsearch>
        <region>MA</region><market>RL</market>
        <recordcount>5000</recordcount>
    </SearchQuery>"
}
This fails with a "EXCEPTION: The remote server returned an error: (400) Bad Request" message. What am I doing wrong?
                        
Try removing the
?method=instead have only'GetAssignments/'+ data.. also add a break point in your controller to make sure the right method is being hit.