C#

JabApi.MouseClickedDelegate mcd = new  JabApi.MouseClickedDelegate(HandleMouseClickedDelegate);
JabApi.setMouseClickedFP(mcd);

table 50109 "Workers"
{
    DataClassification = ToBeClassified;

    fields
    {
        field(1; "No."; Code[20])
        {
            DataClassification = ToBeClassified;
        }

        field(10; "First name"; Text[50])
        {
            DataClassification = ToBeClassified;
        }

        field(20; "Last Name"; Text[50])
        {
            DataClassification = ToBeClassified;

        }

        field(40; FunctionName; Text[50])
        {
            DataClassification = ToBeClassified;

        }
    }

    trigger OnInsert()
    var
        myInt: Integer;
    begin

    end;

    trigger OnModify()
    var
        myInt: Integer;
    begin

    end;

    trigger OnDelete()
    var
        myInt: Integer;
    begin

    end;
}

page 50108 "Workers Card"
{
    PageType = Card;
    ApplicationArea = All;
    UsageCategory = Administration;
    SourceTable = Workers;

    layout
    {
        area(Content)
        {
            group(General)
            {
                field("No."; "No.")
                {
                    ApplicationArea = Basic;
                    Importance = Promoted;
                }

                field("First name"; "First name")
                {
                    ApplicationArea = Basic;
                }

                field("Last name"; "Last name")
                {
                    ApplicationArea = Basic;
                }

                field(FunctionName; FunctionName)
                {
                    ApplicationArea = Basic;

                }
            }
        }
    }
}

page 50109 "Workers List"
{
    PageType = List;
    ApplicationArea = All;
    UsageCategory = Lists;
    SourceTable = Workers;

    layout
    {
        area(Content)
        {
            repeater(Group)
            {
                field("No."; "No.")
                {
                    ApplicationArea = Basic;
                }

                field("First name"; "First name")
                {
                    ApplicationArea = Basic;
                }

                field("Last Name"; "Last Name")
                {
                    ApplicationArea = Basic;
                }

                field(FunctionName; FunctionName)
                {
                    ApplicationArea = Basic;
                }
            }
        }
    }
}

<?xml version = "1.0" encoding = "utf-8" ?>
<ExportedData>
    <TenantWebServiceCollection>
        <TenanatWebService>
            <ObjectType>Page</ObjectType>
            <ObjectID>50108</ObjectID>
            <ServiceName>WorkersWS</ServiceName>
            <Published>true</Published>
        </TenanatWebService>
    </TenantWebServiceCollection>
</ExportedData>

listBox1.Items.Clear();
WorkersReadFromAlWebService = new List<WorkerClass>();
string _wsURL = "https://api.businesscentral.dynamics.com/v2.0/SomeFunfyGuid/Sandbox/WS/CRONUS%20NL/Page/WorkersWS";
string _userName = "UserName";
string _wsKey = "Password";

//Create an instance of the D365BC SOAP WS
BasicHttpBinding _binding = new BasicHttpBinding();

//Set https usage
_binding.Security.Mode = BasicHttpSecurityMode.Transport;
_binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.Basic;

using (WorkersWS_PortClient _ws = new WorkersWS_PortClient(_binding, new EndpointAddress(_wsURL)))
{
    _ws.ClientCredentials.UserName.UserName = _userName;
    _ws.ClientCredentials.UserName.Password = _wsKey;

    //Filter
    List<WorkersWS_Filter> _filters = new List<WorkersWS_Filter>();
    WorkersWS_Filter _filter = new WorkersWS_Filter
    {
        Field = WorkersWS_Fields.No,
        Criteria = "*"
    };
    _filters.Add(_filter);

    try
    {
        foreach (WorkersWS _workerWS in _ws.ReadMultiple(_filters.ToArray(), "", 0))
        {
            WorkerClass _wc = new WorkerClass();
            _wc.E_Tag = _workerWS.Key;
            _wc.First_Name = _workerWS.First_name;
            _wc.Last_Name = _workerWS.Last_Name;
            _wc.FunctionName = _workerWS.FunctionName;
            WorkersReadFromAlWebService.Add(_wc);
            listBox1.Items.Add(_workerWS.Last_Name + " / " + _workerWS.First_name + " (No: " + _workerWS.No + ")");
        }
    }
    catch (Exception _ex)
    {

    }
}

ClearWorker();//Clears some textboxes

//using WorkersWS uses a List page in the background, which is capable of updating and inserting. WorkersWebService uses a card page, which is NOT capable of updating and inserting. But unfortunately the errors remain.

string _url = "https://api.businesscentral.dynamics.com/v2.0/SomeFunkyGuid/Sandbox/ODataV4/Company('CRONUS%20NL')/WorkersWS";
//string _url = "https://api.businesscentral.dynamics.com/v2.0/SomeFunkyGuid/Sandbox/ODataV3/Company('CRONUS%20NL')/WorkersWS";//ODATA V3, makes no difference
HttpWebRequest _request = (HttpWebRequest)WebRequest.Create(_url);//
_request.ContentType = "application/json; charset=utf-8";
_request.Headers["Authorization"] = "Basic " + Convert.ToBase64String(Encoding.GetEncoding("ISO-8859-1").GetBytes("UserName:Password"));
_request.Accept = "*/*";
_request.KeepAlive = true;
//_request.Method = "PUT";//error 405: Method is not allowed
_request.Method = "PATCH";//error 405: Methode is not allowed
string _etag = rtbE_Tag.Text;
_request.Headers["If-Match"] = String.Format("W/\"{0}\"", _etag);
//_request.Method = "POST";//(when using POST, the 4 lines above are commented out)error 400: invalid method

string body = "{" + Environment.NewLine +
                    "\"No\":" + tbNo.Text + "," + Environment.NewLine +
                    "\"First_name\":\"" + tbFirstName.Text + "\"," + Environment.NewLine +
                    "\"Last_Name\":\"" + tbLastName.Text + "\"," + Environment.NewLine +
                    "\"FunctionName\":\"" + tbFunctionName.Text + "\"," + Environment.NewLine +
                  "}";

byte[] data = Encoding.ASCII.GetBytes(body);

try
{
    _request.ContentLength = data.Length;

    Stream requestStream = _request.GetRequestStream();
    requestStream.Write(data, 0, data.Length);
    requestStream.Close();

    HttpWebResponse _response = _request.GetResponse() as HttpWebResponse;//Here we get the exception errors 400 or 405
    Console.WriteLine(_response.StatusCode);
}
catch (Exception ex)
{

}

string _wsURL = "https://api.businesscentral.dynamics.com/v2.0/SomeFunkyGuid/Sandbox/WS/CRONUS%20NL/Page/WorkersWS";
string _userName = "Username";
string _wsKey = "Password";

//Create an instance of the D365BC SOAP WS
BasicHttpBinding _binding = new BasicHttpBinding();

//Set https usage
_binding.Security.Mode = BasicHttpSecurityMode.Transport;
_binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.Basic;

using (WorkersWS_PortClient _ws = new WorkersWS_PortClient(_binding, new EndpointAddress(_wsURL)))
{
    _ws.ClientCredentials.UserName.UserName = _userName;
    _ws.ClientCredentials.UserName.Password = _wsKey;

    try
    {
        WorkersWS _wws = _ws.Read(tbNo.Text);
        if (_wws.No == tbNo.Text)
        {
            _wws.First_name = tbFirstName.Text;
            _wws.Last_Name = tbLastName.Text;
            _wws.FunctionName = tbFunctionName.Text;
            _ws.Update(ref _wws);

            if (_wws.No == tbNo.Text)
            {
                tbResult.Text = "Update success.";
            }
        }
    }
    catch (Exception _ex)
    {

    }
}