null

问题 Hola caballeros, I am stumped, mystified, and worse yet, stymied: in my first tab bar project I have an object that is instance of a subclass "BarGraph of UIView, which I've used before without trouble. In this project I do an alloc-init in the viewDidLoad method of the second viewController, graphViewController. This sets up the BarGraph. The data which is read in is displayed properly by that object. The trouble comes when I use a tab to go to a different viewControler where I add to the

问题 I have on view show.html.erb <%= @question.user.lesson_id %> and this is on browser a number. my questions_controller.rb is def show @question = Question.find(params[:id]) @comments = @question.comments.all if user_signed_in? @rating_currentuser = @question.ratings.find_by_user_id(current_user.id) unless @rating_currentuser @rating_currentuser = current_user.ratings.new end end and my questions_controller_test.rb test "should show question signed in" do sign_in users(:user2) get :show, :id =>

问题 This question is about Postgresql 8.3 . I've got a table with a field containing conditions like 'lastcontact is null'. In code, I want to loop through this table and for each record, I want to check 'if condition then', like in this example: FOR myrec IN SELECT * FROM tabel ORDER BY colorlevel, volgnummer LOOP if (myrec.conditie) then raise notice 'Condition % is true', myrec.conditie; else raise notice 'Condition % is false', myrec.conditie; end if; END LOOP; The table which I have called

问题 This question is about Postgresql 8.3 . I've got a table with a field containing conditions like 'lastcontact is null'. In code, I want to loop through this table and for each record, I want to check 'if condition then', like in this example: FOR myrec IN SELECT * FROM tabel ORDER BY colorlevel, volgnummer LOOP if (myrec.conditie) then raise notice 'Condition % is true', myrec.conditie; else raise notice 'Condition % is false', myrec.conditie; end if; END LOOP; The table which I have called

问题 there is this function called Nz() in visual basic for application. the function checks variable nullity and returns a provided value if it finds the variable is null. i try to write the same function in php, which looks like below: function replace_null($value, $replace) { if (!isset($value)) { return $replace; } else { return $value; } } $address = replace_null($data['address'], 'Address is not available.'); of course, if $data['address'] is found null, php will stop executing the code and

问题 there is this function called Nz() in visual basic for application. the function checks variable nullity and returns a provided value if it finds the variable is null. i try to write the same function in php, which looks like below: function replace_null($value, $replace) { if (!isset($value)) { return $replace; } else { return $value; } } $address = replace_null($data['address'], 'Address is not available.'); of course, if $data['address'] is found null, php will stop executing the code and

问题 This question already has answers here : What is the difference between an int and an Integer in Java and C#? (26 answers) Closed 5 years ago . which is the best way to set already defined int to null ? private int xy(){ int x = 5; x = null; //-this is ERROR return x; } so i choose this private int xy(){ Integer x = 5; x = null; //-this is OK return (int)x; } Then i need something like : if(xy() == null){ // do something } And my second question can i safely cast Integer to int? Thanks for

问题 <asp:Repeater ID="rptLessons" runat="server"> <ItemTemplate> <tr> <td><%#Eval("fullname")%></td> <td><%#isCompleted(Eval("totallessons"), Eval("completedlessons"), Eval("totalNumAvail"), Eval("totalNumCorrect"))%></td> <td><%#FormatPercent(Eval("totalnumcorrect") / Eval("totalNumAvail"))%> <%-- (<%#Eval("totalnumcorrect")%> / <%#Eval("totalNumAvail")%>) --%></td> <td><%#FormatPercent(Eval("completedlessons") / Eval("totallessons"))%> <%-- (<%#Eval("completedlessons")%> / <%#Eval("totallessons

问题 The setup is Angular 5 and .net core Web Api. At the controller, model binding always results in null while trying to bind to a complex object. Code is provided below. This example is adapted from another SO answer . but its not working for me. Controller: [Route("demopost1")] [HttpPost] public async Task < IntResultEntity > DemoPostList1([FromBody]DemoPostViewModel payload) { return await Task.FromResult(new IntResultEntity { Result = 0 }); } Models: public class DemoPostModel { public