Comments by Daniel Andrei Popescu

Daniel Andrei Popescu 12-Jun-18 7:12am View

Now I understand.Thank you again and also for the explanation.

Daniel Andrei Popescu 12-Jun-18 7:05am View

Thank you,Thaddeus Jones for the solution.It seemed i was doing it correctly except for the part where I continuously add comboboxes to the panel.I thought that if I add it once to the panel it would be enough.Best regards!

Daniel Andrei Popescu 28-May-18 5:26am View

Thank you for your response,sir.It was really helpful :)

Best regards!

Daniel Andrei Popescu 16-May-18 14:35pm View

Thank you for your response.The thing is that I would like it to update every time a student swipes the card over the card reader,as the value(the serial nr) in the textbox is checked with the database.I binded to a dependancyproperty that automatically should insert the new row,it basically works like a button.Do you think it is possible to assign the function to it so that it will update automatically at every row inserted?

Daniel Andrei Popescu 15-May-18 5:39am View

Thank you,sir.I understand,and there are values in table RegisterStudent.I have tried the approach you suggested,but it still can't read the serial number.I looked over the binding also to see if I miss something.I have updated the question with the binding as well.Best regards!

Daniel Andrei Popescu 15-May-18 4:38am View

Thank you so much for your response.I have tried as you suggested,but when I debug it still give me null values.I have also tried to set the SN as a serial nr to test i maybe it has something to do with the binding,but no.It doesn't work either way.This is the error that I get:
"The parameterized query '(@SN nvarchar(4000) @sNr int,@fName nvarchar(4000),lName nvarch' expects the parameter '@SN',which was not supplied).I believe this is because i didn't declare it as null,which it is when I debug it.

Daniel Andrei Popescu 9-May-18 5:25am View

Thank you for the advice.Regarding my password,yes,I have tried to encrypt it and check if the two hash values are the same,as i have it in my function.I dont' understand the sintax"store password in clear text".I have a password box which I use in the view,I have a passwordhelper class from which I bind the passwordbox and also I encrypt it when I store the values into the db and when I select them from the database. As for the UserName parameter,it still doesn't work.I have also tried this.So basically it reads the value,but won't accept the credentials because i didn't set the variable.

Daniel Andrei Popescu 9-May-18 4:44am View

Thank you for your response.It is not null.It holds the value,that's the problem.When I set the breakpoint and i insert the value in the textbox and then debug it,I get the value without any problem.

Daniel Andrei Popescu 8-May-18 5:26am View

Hello sir and thank you for your response.I couldn't response earlier because of some problems in my code.I have an error regarding the mapping to the AvailableCourses since SNTeacher is not a column from AvailableCourses,only CourseID...It's not working unfortunately.

Daniel Andrei Popescu 2-May-18 7:51am View

Sir,now I have noticed that when I want to debug and I'm setting the breakpoint for the method where I get the education in the combobox,it breaks directly into it without entering the application and breaking when I select the education.What could be the problem?I have looked at the binding and everything is ok.

Daniel Andrei Popescu 2-May-18 7:33am View

Thank you sir for your response,but unfortunately is not working.I still don't get anything when I click the button.

Daniel Andrei Popescu 2-May-18 7:15am View

Thank you for your response!You are right.I didn't actually knew that they have to match.I knew I have to pass the values from view to VM,but thank you for the lesson.Next time I won't do the same mistake :).Best regards!

Daniel Andrei Popescu 26-Apr-18 7:33am View

Thank you for your response.No,my error is different now.I set the breakpoint,but the value is null,but when I replace it with a string,it works by taking the courses for the program that I have just written as a string.The problem is that the binding is correct,I don't get any error and when I had the project on the previous PC,it worked perfectly.I have noticed anyhow that my database is constructed twice every time I make a new one.Maybe that is a problem?

Daniel Andrei Popescu 19-Apr-18 8:23am View

Hello,I have manage to do it and take the value :).I have instead a problem with saving the data into the database.I'm using entity framework and I have a DelegateCommand SaveCommand that saves all the data inserted by the lecturer.I have pasted the method that i'm using in order to save it and i'm using EF with database first.When I click the button,nothing happens,but if i put breakpoints to see if the data was passed from one value to another,it does,even the courseName.What should I do in order to make it work?I have tried to put a messagebox at the end that could confirm the registration,but I don't know if what i did was efective at all.

Daniel Andrei Popescu 17-Apr-18 7:27am View

When it has sth like "TstDemoDBEntities" it doesn't mean that he's using entity framework?If i'm mistaken,then I apologize :) This is a method that I have used when I had the binding with the combobox and it worked perfectly.

Daniel Andrei Popescu 11-Apr-18 8:33am View

Thank you sir for your help.I will try it today to see if I'll get to a correct solution and I will upload the solution later on for everybody.Until then I'll mark your answer as correct so that other people can have a proper example to look at in case of a similar problem.Best wishes!

Daniel Andrei Popescu 11-Apr-18 6:18am View

I have looked at the output window and I see 2 errors for binding which are the following:
System.Windows.Data Error: 40 : BindingExpression path error: 'CheckCommand' property not found on 'object' ''Cours' (HashCode=1598569)'. BindingExpression:Path=CheckCommand; DataItem='Cours' (HashCode=1598569); target element is 'CheckBox' (Name=''); target property is 'Command' (type 'ICommand')

System.Windows.Data Error: 40 : BindingExpression path error: 'IsSelected' property not found on 'object' ''Cours' (HashCode=1598569)'. BindingExpression:Path=IsSelected; DataItem='Cours' (HashCode=1598569); target element is 'CheckBox' (Name=''); target property is 'IsChecked' (type 'Nullable`1).

Daniel Andrei Popescu 11-Apr-18 4:53am View

I have tried right now to do it by using the listbox but it's still not working...Thank you for your time but i don't think i'll manage to pass the error to soon.I work on it for 2 weeks,reviewing everything ans staring back again with the binding from scratch.I have no idea why is not working...

Daniel Andrei Popescu 11-Apr-18 4:27am View

Thank you for your response,I will try this approach and I'll come back with an answer.Regarding errors in this case,I don't see any error,everything runs perfectly except for the fact that the courseName is null thanks to the checkbox.

Daniel Andrei Popescu 11-Apr-18 4:26am View

Hello,thank you for your response.I did that already.

Daniel Andrei Popescu 10-Apr-18 7:15am View

I didn't say that.I have 3 things that I don't know and could't find anything relevant for it so I've asked this question because one thing is to have the entire code in front of you and be able to actually explain the person what he/she did wrong and other is to post question after question along with fractions of the code and hear people saying that they are not sure or they don't really get what i'm saying because they don't have the entire code in front of them.Plus if i wanted someone to make my code,I would't waste my time asking people to explain things to me and help me understand where i'm worng,i would hire someone to do it for me.

Daniel Andrei Popescu 10-Apr-18 4:45am View

It worked at the end.I redone everything that depended on Entity Framework,even the relations between tables.Now my Entity Framework works!Thank you for your time! :)

Daniel Andrei Popescu 9-Apr-18 7:32am View

Ok,thank you for your response.If you will make your comment an answer,I will mark it as"Correct".Best wishes!

Daniel Andrei Popescu 9-Apr-18 7:20am View

And if I'm using DB first,would this be a problem?

Daniel Andrei Popescu 9-Apr-18 6:54am View

Hello,Thank you for your response.I managed to do it,but I have another problem with my database.I created the db in Visual Studio and I'm using DB first in my project,and I noticed that the error:Error 159: "EntityType 'DatabaseStudentsModel.Login' has no key defined" is persisting.I have deleted the table from the db,but when I want to create a new one it says that a table like the one I want to create already exists.How can I manage to get into the db and delete the table there or to make it work ?Best regards,

Daniel Andrei Popescu 5-Apr-18 6:48am View

Yes,I know because I have another login form that does that.This one basically has to check the password(the password is the serial nr from the NFC tag).I used focus on the textbox in order to read the SN right away.Basically I need a way to automatically log in as the user hovers the NFC tag over the card reader.The card reader is already set to read values from the NFC tag.Regarding the password,I know that is not secure,but I'm working on it(I'm still learning this because I'm a beginner in MVVM).

Daniel Andrei Popescu 5-Apr-18 3:08am View

Thank you,I understand what you are saying but this is not up to me,it's up to my boss,so any help would be appreciated :)

Daniel Andrei Popescu 4-Apr-18 3:57am View

Nope,I didn't because I don't waste time staying and formulating an entire description of my problem unless I really need help...Best regards!

Daniel Andrei Popescu 4-Apr-18 3:55am View

Thank you for letting me know.I have now changed it so that the other table will also have "education".

Daniel Andrei Popescu 3-Apr-18 3:43am View

Yes,thank you for asking.I still do,i couldn't find the issue.

Daniel Andrei Popescu 23-Mar-18 9:38am View

Hello,
This doesn't depend on what I want.I'm an intern at the university where I'm studying and the staff there told me that this is how they want the system to be.I also made a normal authentication in case someone happens to forget the card.The app is used only by lecturers,and it's their responsibility if this sort of things happen.Every card has a serial nr inside and it is unique.In this case,not anybody can access the system since only the lecturers have the card and on every lecturer's card it's a different serial nr.

Daniel Andrei Popescu 23-Mar-18 7:55am View

And the method used for retrieving the value is the same

Daniel Andrei Popescu 23-Mar-18 7:54am View

 public DelegateCommand CheckCommand
        {
            get
            {
                if (checkCommand == null)
                    checkCommand = new DelegateCommand(i => Checkprocess(i), null);
                return checkCommand;
            }
            set
            {
                checkCommand = value;
                NotifyOnPropertyChange("CheckCommand");
            }
        }

        private void Checkprocess(object i)
        {
            isChecked = true;
        }

Daniel Andrei Popescu 23-Mar-18 7:50am View

Yes,unfortunately. I have managed to make the IsCheked==true through a delegatecommand,but my courseName is still null when I want to insert the value to the DB.

Daniel Andrei Popescu 22-Mar-18 4:19am View

I have tried so many things yesterday and I was too tired at a certain point,I apologize for not answering earlier.I put a breakpoint and saw that the value was false.Initially I had my bool in the view-model.I tried another approach by declaring it in the model class and call it thorugh the reference to the model (reference was t) and i made something like-if(t.isChecked==true).This time I get the bool value in the view when I want to bind it,but still get the value false.I started then wondering that my problem is the binding since everything was working fine except for this.Then I started making some research and tried 3 different approaches of binding a checkbox,including a delegate command and a read-only property.Nothing worked...

Daniel Andrei Popescu 22-Mar-18 4:15am View

Hello

Daniel Andrei Popescu 21-Mar-18 6:55am View

Hello,CourseName is the property in the checkbox that I'm testing and about the relationship,I don't really understand what you're referring to.I am still a begginner with MVVM so i would really appreciate if you would rephrase the question. :)

Daniel Andrei Popescu 20-Mar-18 6:32am View

Yes,i know...Thank you very much for your help!Have a beautiful day :)

Daniel Andrei Popescu 20-Mar-18 4:23am View

I don't know Gerry Schmitz what you mean by auto-generated PK,but i can tell you that I started the project by making the database and then I auto-generated the model with EF.I was the one setting the PK based on how I wanted my system to be.Regarding the use of LINQ,I am a new to LINQ queries and I have worked with it a little,but I didn't know how to approach this so I stayed on my track using sql queries.I tried using LINQ in making the registration,but I got confused about the inner join.

Daniel Andrei Popescu 20-Mar-18 4:16am View

Hello,first of all I'm using db first because i thoght it would be a much easier and logical approach.Second of all,a teacher has multiple courses that will select from a listbox,that's why I passed the courseName.I understand that it's not the best approach,but it can be changed.My password is limited to nr because my system is made in such way that the teacher can log in with his NFC card(and the NFC card has a serial nr that contains aprox 10-12 numbers).

Daniel Andrei Popescu 19-Mar-18 6:38am View

I found the solution.It was all in the binding at the .xaml file because after a short research about the actual problem,i discovered that the method was good,but i had to have in the combobox:"Text={Binding Education}" and it works perfectly.

Daniel Andrei Popescu 19-Mar-18 6:22am View

Hello,no there are not null values in the education column.Instead,there are 4 values that i have binded to a combobox.

Daniel Andrei Popescu 19-Mar-18 5:16am View

Hello,thank you so much for your response.I have tried the version that you gave me but I still get n error at "CourseName" saying that my table "Cours" does not contain a definition for it.Since I take your advice into consideration,I have also tried instead of"select new Cours{CourseName = data.courseName}"-"select new {CourseName = data.courseName}" but in this case i have an error at the query saying that the type of the query is not compatible as IQueryable.Beside this,I understand your logic from the solution and I will try to adapt it as much as I can and hope it will work.

Thank you and best regards,

Daniel Andrei Popescu 13-Mar-18 8:06am View

Hi,John,if you know where I can find an example for my problem or if you can give me an advice,it will be more than enough.I have tried to find something relevant everywhere over the internet,and the worst part is that I'm new in MVVM and WPF so any help would be appreciated!

Daniel Andrei Popescu 13-Mar-18 7:05am View

Right now I have tried it,nothing will change.
this is my method:
Cours cr = new Cours();
string query = "";

SqlConnection conn = new SqlConnection(@"Data Source=(LocalDB)\\MSSQLLocalDB;AttachDbFilename=C:\\Users\\User\\source\repos\\VIAApp2Demo\\VIAApp2Demo\\DB\\DatabaseStudents.mdf;Integrated Security=True;Connect Timeout=30");

conn.Open();
if (Education.Any(p => p.education == "ICT Engineering" && p.courseID < 2000))
{
query = "Update Courses SET courseName=@courseName and courseID=@courseID ";
SqlCommand cmd = new SqlCommand(query, conn);
SqlParameter Coursename= cmd.Parameters.AddWithValue("@courseName", SqlDbType.NVarChar);
cmd.Parameters["@courseName"].Value = courseName;
if (Coursename==null)
{
Coursename.Value = DBNull.Value;
}
SqlDataReader rd = cmd.ExecuteReader();
try
{
while(rd.Read())
{
using (DatabaseStudentsEntities1 db = new DatabaseStudentsEntities1())
{
courseName = db.Courses.Select(s => new Cours() { courseName = s.courseName }).ToList();
}
cmd.ExecuteNonQuery();
}
rd.Close();
}catch(Exception ex)
{
MessageBox.Show(ex.Message);
}
}

Daniel Andrei Popescu 13-Mar-18 6:55am View

OK,interesting approach.I will try it now and let you know!

Daniel Andrei Popescu 13-Mar-18 5:26am View

Deleted

Hello ,saimanisha!I'm taking it from the database,with entity framework.I tried to do it with linq queries but i don't think is the right approach.

Comments by Daniel Andrei Popescu (Top 47 by date)