Setting the Text property of a DropDownList ComboBox to an invalid value doesn't raise exception? -


I'm looking at ways to solve a problem with the Winforms application, which uses the combo box control special As a form, the combo box (style = dropdown list) is bound to a data source and, because the user navigates through any other data, the "text" property of the combo box property is set - And the user can choose some other value.

Trouble starts when I have not specified the "text" attribute in the list of available items. It seems that nothing happens, take the following simple examples: 

  Public Partial Sections Form 1: Form {Public Form 1 () {Initial Group (); MyComboBox1.DropDownStyle = ComboBoxStyle.DropDownList; //myComboBox1.Items.AddRange (new [] ("one", "two", "three"}; list & lt; keyValuePair & lt; int32, string & gt; & gt; value = new list & lt; KeyvaluePair & lt; Int32, string & gt; & gt; (); Values.Add (New Key Val Peer & lt; Int32, String & gt; (1, "one"); Values.Add (New KeyWeeker & lt ;); Values.Add (new keyweeper  (3, "three"); MyComboBox1.DataSource = value; MyComboBox1.ValueMember = "Key"; MyComboBox1.DisplayMember = "Value"; Button 1. Click = (S, E) => {MyComboBox1.Text = "Four";}; Button 2. Click + = (S, E ) = & Gt; {MyComboBox1.SelectedIndex - = 1;};}} Public Works C MyComboBox: System.Windows.Forms.ComboBox {public override string text {get {return base.Text;} set {MessageBox.Show (value); Base.Text = value;}}}

This technique is used across a large application, so when it was seen that (in the example above) "text" is not "four" "nothing, I thought It was possible that I could frustrate it and throw an exception. In reality, such code is pasted in such a way: 

  if (myDataRow.IsBlahNull ()) myComboBox1.Text = ""; Other myComboBox1.Text = myDataRow.Blah;

Now, when I appreciate the setting of the "SelectIndex = 1" setting, the "IsNull" case would be better, the fact is that myDataRow.Blah can not be a valid value is. In addition, the app is written (and live) so that fewer changes are better.

So, my immediate idea was to "Override text property setter and check that the value is in the list" that, it has been found, it is not as easy as it is easy Will happen. The problem is that the "text" property is set in all sorts of situations, in all circumstances, for example, it is set when the datasource property is assigned, or when the selected index is set to 1, besides it Represents the string of the selected item - so if you have the combo box control that is connected to a list of key value pairs, you'll get "[key, value ] "To get something like" text "property set. If it is bound for datatable / datvice, then you get the representation of string of data arrows, and it becomes difficult to find out.

At this time I thought that there could be another way to get the desired result (which is to find the text property setting at some invalid value - which does nothing) .

Any thoughts?

After reflection, is this a fair job? 

  /// & lt; Summary & gt; /// sets or sets the text associated with this control /// & lt; / Summary & gt; Public override string text {return base. Text; } Set {base.Text = value; If ((value! = Null) & amp; (base.Text! = Value)) if (value == "") this.SelectedIndex = -1; And express new logic (text property of "string {format} can not be set to" {1} \ ".", This.Name, value)); }}

Comments

Post a Comment

Popular posts from this blog

Python SQLAlchemy：AttributeError: Neither 'Column' object nor 'Comparator' object has an attribute 'schema' -

I tried to create a new database in my project, but when I run the script, I get this error, I have another project, this type of definition worked before, but now it gets a single error. I am using Python 2.7.8 and the version of SQLAlchemy module is 0.9.8. By the way, using a project flask- SQLAlchemy, it works well, I'm confused. Traceback information is as follows: Traceback (most recent call final): File "D: / Projects / IOM / db_create.py", line 4, & lt; Module & gt; From the models the base file "D: \ Projects \ OO-IM \ models.py", in line 15, in the & lt; Module & gt; Column ( 'followed_id', int (), ForeignKey ( 'user.id')) file "C: \ Python27 \ lib \ site-packages \ SQLAlchemy \ SQL \ schema.py", line 369, __new__ schema = metadata. Schema file "C: \ Python27 \ lib \ site-packages \ SQLAlchemy \ SQL \ elements.py", line 662, AttributeError in __getattr__ key): Neither 'column' object nor ...
Read more

java - How not to audit a join table and related entities using Hibernate Envers? -

I use Eners to be hibernate to audit my institutions. I have an audit entity, Foo , which includes a list & lt; Bars & gt; However, I do not want to audit the bar institutions, in the form of properties, I have written that: @inti @edicated public class Foo {@JoinTable (name = "T_FOO_BAR", joinColumns = @JoinColumn (name = "FOO_ID"), inverseJoinColumns = @JoinColumn (Name = "BAR_ID")) @ManyToMany (Cascade = Persist) @ Indited (targetAuditMode = RelationTargetAuditMode.NOT_AUDITED ) Public listing & lt; Bars & gt; GetBars () {Return bars; }} Now, I want to retrieve an amendment of foo : AuditReader reader = AuditReaderFactory.get (GetEntityManager ()); FU modification = (FU) reader.CreativeTeA () .entensEtrevision (Foo Class, 42) .getSingleResult (); Unfortunately, when I want to retrieve all the data (i.e. when it loads lazy times ), error me ORA-00942: table or view is not present , because Tried to query this: Sel...
Read more

mongodb - CakePHP paginator ignoring order, but only for certain values -

While pagging my user model in kppp, I can sort with some values, but not others. For example, I can order results from created or email , for example, but username or reputation seems to come back order by arbitrary command for example with a list of users: $ this-> paginate = array ('condition' => array ( 'User.is_active' = & gt; true), 'border' => 24, 'order' => array ('User.created' => DESC)); Works as expected, but $ this - & gt; Paged = array ('conditions' = & gt; array (' user.isIactive '= & gt; true),' border '= & gt; 24,' command '= & gt; array (' user repeats' = ' & Gt; DESC ')); No, no. I first thought that this could be a database issue, but when I search the database directly, sorted as expected. Note: I am using Mangodebi with the Mongo DB plugin of Ichikawa for the KPPHP; Pagnetizing users are used to work properl...
Read more