public void select(int z)
{
ListBox1.SelectedIndex = z;
ListBox1.SelectedItem = ListBox1.Items[z];
ListBoxItem
selectedItem=ListBox1.ItemContainerGenerator.ContainerFromItem(this.ListBox1.SelectedItem)
as ListBoxItem;
selectedItem.Focus();
}
In this method I'm trying to select element in the listbox, But the reference variable carrying value is null which is returning by the selection code.
"ListBox1.ItemContainerGenerator.ContainerFromItem(this.ListBox1.SelectedItem) as ListBoxItem;"
I have debugged my code and keenly observed that the values are coming into the ListBox1 object, but still it is returning a null value.
ListBoxItem selectedItem = ListBox1.ItemContainerGenerator.ContainerFromItem(this.ListBox1.SelectedItem) as ListBoxItem;
TextBox1.Text = selectedItem.Content.ToString();
or is it
TextBox1.Context = selectedItem.Content.ToString();
Good luck :)
Related
I'm running a Apps Script to create a data entry form. Sometimes my searchRecord function works if I run it several times. Sometimes it doesn't pull any info, but never gives me the warning screen, sometimes it pulls the info from the last search. I'm not sure where the problem is. I have copied the code below.
//Function to Search the record
function searchRecord(){
var myGoogleSheet=SpreadsheetApp.getActiveSpreadsheet(); //declare a variable and set with active Google Sheet
var shUserForm=myGoogleSheet.getSheetByName("User Form"); //declare a variable and set with the User Form reference
var datasheet=myGoogleSheet.getSheetByName("Existing Customers"); //declare variable and set the reference of database sheet
var str=shUserForm.getRange("B2").getValue(); //get data input for search button
var values=datasheet.getDataRange().getValues(); //getting the entire values from the used range and assigning it to values variable
var valuesFound=false; //variable to store boolean value
for (var i=0; i<values.length; i++)
{
var rowValue=values[i]; //declare a variable and storing the value
//checking the first value of the record is equal to search item
if(rowValue[6]==str){
shUserForm.getRange("B12").setValue(rowValue[0]);
shUserForm.getRange("B15").setValue(rowValue[1]);
shUserForm.getRange("B23").setValue(rowValue[2]);
shUserForm.getRange("B17").setValue(rowValue[3]);
shUserForm.getRange("E17").setValue(rowValue[4]);
shUserForm.getRange("B8").setValue(rowValue[6]);
shUserForm.getRange("E8").setValue(rowValue[7]);
shUserForm.getRange("B19").setValue(rowValue[8]);
shUserForm.getRange("E19").setValue(rowValue[9]);
shUserForm.getRange("B21").setValue(rowValue[10]);
shUserForm.getRange("E21").setValue(rowValue[11]);
shUserForm.getRange("E23").setValue(rowValue[12]);
shUserForm.getRange("E12").setValue(rowValue[13]);
shUserForm.getRange("B25").setValue(rowValue[14]);
shUserForm.getRange("E25").setValue(rowValue[15]);
shUserForm.getRange("B27").setValue(rowValue[16]);
shUserForm.getRange("E27").setValue(rowValue[17]);
shUserForm.getRange("B29").setValue(rowValue[18]);
shUserForm.getRange("E29").setValue(rowValue[19]);
shUserForm.getRange("B31").setValue(rowValue[20]);
shUserForm.getRange("E10").setValue(rowValue[21]);
shUserForm.getRange("B33").setValue(rowValue[22]);
shUserForm.getRange("B35").setValue(rowValue[23]);
shUserForm.getRange("B37").setValue(rowValue[24]);
shUserForm.getRange("E31").setValue(rowValue[25]);
shUserForm.getRange("E35").setValue(rowValue[26]);
shUserForm.getRange("B39").setValue(rowValue[27]);
shUserForm.getRange("E39").setValue(rowValue[27]);
shUserForm.getRange("B41").setValue(rowValue[29]);
shUserForm.getRange("E15").setValue(rowValue[30]);
shUserForm.getRange("B43").setValue(rowValue[31]);
shUserForm.getRange("E43").setValue(rowValue[32]);
shUserForm.getRange("B45").setValue(rowValue[33]);
shUserForm.getRange("E45").setValue(rowValue[34]);
shUserForm.getRange("B47").setValue(rowValue[35]);
shUserForm.getRange("B49").setValue(rowValue[36]);
shUserForm.getRange("B10").setValue(rowValue[37]);
shUserForm.getRange("E37").setValue(rowValue[5]);
valuesFound=true;
return;//come out from the loop
}
if(valuesFound=false){
//to create the instance of the user-interface environment to use the alert function
var ui=SpreadsheetApp.getui();
ui.alert("No Record Found");}
}
}
Solution
There are different points in your code that could be improved, I attach the updated function correcting the basics:
Indentation: This is easy to fix, just press ctrl + shft + i to correctly indent the code.
Break statement: Use the word break to break a loop.
Wrong comparison operator: The second if has only one = instead of two ==. Check Expressions and operators
Structural logic: Inside the for loop there are two ifs. Only the second one depends on the value of the valuesFound variable, which when modified breaks the loop, so it is not really doing anything.
Readability: It is difficult to understand what the code is doing and so many setValue boxes with no apparent connection is confusing.
In addition, it is difficult to offer help if the behavior of the function is variable and the reason is not known. Apparently, it should always give the same result.
Updated code
function searchRecord() {
var ss = SpreadsheetApp.getActiveSpreadsheet(); //declare a variable and set with active Google Sheet
var shUserForm = ss.getSheetByName("User Form"); //declare a variable and set with the User Form reference
var datasheet = ss.getSheetByName("Existing Customers"); //declare variable and set the reference of database sheet
var str = shUserForm.getRange("B2").getValue(); //get data input for search button
var values = datasheet.getDataRange().getValues(); //getting the entire values from the used range and assigning it to values variable
var valuesFound = false; //variable to store boolean value
var ui = SpreadsheetApp.getui();
for (var i = 0; i < values.length; i++) {
var rowValue = values[i]; //declare a variable and storing the value
//checking the first value of the record is equal to search item
if (rowValue[6] == str) {
shUserForm.getRange("B12").setValue(rowValue[0]);
shUserForm.getRange("B15").setValue(rowValue[1]);
shUserForm.getRange("B23").setValue(rowValue[2]);
shUserForm.getRange("B17").setValue(rowValue[3]);
shUserForm.getRange("E17").setValue(rowValue[4]);
shUserForm.getRange("B8").setValue(rowValue[6]);
shUserForm.getRange("E8").setValue(rowValue[7]);
shUserForm.getRange("B19").setValue(rowValue[8]);
shUserForm.getRange("E19").setValue(rowValue[9]);
shUserForm.getRange("B21").setValue(rowValue[10]);
shUserForm.getRange("E21").setValue(rowValue[11]);
shUserForm.getRange("E23").setValue(rowValue[12]);
shUserForm.getRange("E12").setValue(rowValue[13]);
shUserForm.getRange("B25").setValue(rowValue[14]);
shUserForm.getRange("E25").setValue(rowValue[15]);
shUserForm.getRange("B27").setValue(rowValue[16]);
shUserForm.getRange("E27").setValue(rowValue[17]);
shUserForm.getRange("B29").setValue(rowValue[18]);
shUserForm.getRange("E29").setValue(rowValue[19]);
shUserForm.getRange("B31").setValue(rowValue[20]);
shUserForm.getRange("E10").setValue(rowValue[21]);
shUserForm.getRange("B33").setValue(rowValue[22]);
shUserForm.getRange("B35").setValue(rowValue[23]);
shUserForm.getRange("B37").setValue(rowValue[24]);
shUserForm.getRange("E31").setValue(rowValue[25]);
shUserForm.getRange("E35").setValue(rowValue[26]);
shUserForm.getRange("B39").setValue(rowValue[27]);
shUserForm.getRange("E39").setValue(rowValue[27]);
shUserForm.getRange("B41").setValue(rowValue[29]);
shUserForm.getRange("E15").setValue(rowValue[30]);
shUserForm.getRange("B43").setValue(rowValue[31]);
shUserForm.getRange("E43").setValue(rowValue[32]);
shUserForm.getRange("B45").setValue(rowValue[33]);
shUserForm.getRange("E45").setValue(rowValue[34]);
shUserForm.getRange("B47").setValue(rowValue[35]);
shUserForm.getRange("B49").setValue(rowValue[36]);
shUserForm.getRange("B10").setValue(rowValue[37]);
shUserForm.getRange("E37").setValue(rowValue[5]);
valuesFound = true;
break
}
if (valuesFound == false) {
//to create the instance of the user-interface environment to use the alert function
ui.alert("No Record Found");
}
}
}
As described in the documentations:
The const keyword isn’t just for declaring constant variables. You can also use it to create constant values, as well as to declare constructors that create constant values. Any variable can have a constant value.
Can someone explain the use of constant values?
This is a simple example which I hope explains clearly:
Start with two variables and a constant.
var foo = [10,11];
var bar = const [20,21];
const baz = [30,31];
Try to modify foo and it succeeds.
foo.add(12); // [10,11,12]
Try to similarly modify bar and there's an error, because even though bar is a variable, its value was declared to be a constant, thus is immutable.
bar.add(22); // ERROR!
Try to reassign bar to a different value. That works since bar itself was not declared as a constant.
bar = [40,41];
Now, try to modify bar's value again and this time it works, since its new value is not a constant.
bar.add(42) // [40,41,42]
Try to modify baz and there's an error, since baz being declared as a constant itself, its value is inherently immutable.
baz.add(32); // ERROR!
Try reassigning baz to a new value and it fails because baz is a constant and can't be reassigned to a new value.
baz = [50,51]; // ERROR!
void main() {
simpleUse();
finalUse();
constUse();
}
simpleUse() {
print("\nsimple declaration");
var x = [10];
print('before: $x');
x = [5];//changing reference allowed
x.add(10);//changing content allowed
print('after: $x');
}
finalUse() {
print("\nfinal declaration");
final x = [10];
print('before: $x');
// x = [10,20]; //nope changing reference is not allowed for final declaration
x.add(20); //changing content is allowed
print('after: $x');
}
constUse() {
print("\nconst declaration");
const x = [10];
print('before: $x');
// x = [10,20]; //nope -> changing reference is not allowed for final declaration
// x.add(20);//nope -> changing content is not allowed
print('after: $x');
}
Also, variables are simple values like x = 10;
values are instances of enums, list, maps, classes, etc.
I want to add, that another point for const is to guarantee your get the same instance of the object each time you construct it with the same parameters:
class Test {
final int value;
const Test(this.value);
}
void main() {
print(Test(5).hashCode == Test(5).hashCode); // false
print((const Test(5)).hashCode == (const Test(5)).hashCode); // true
}
This is the reason why the const constructor can be difficult to make for all objects since your need to make sure the object can be constructed on compile-time. Also, why after creation of the object no internal state can be changed as the previous answer also shows.
Is there a generic way to retrieve PropertyInfo based on a string value alone, when deeper than one level.
I assume this is probably simple enough, but my search results are only as good as my search criteria, and I think I am having an issue articulating the proper keywords to get search results for what I am after.
I would like to be able to do something like the following (which works perfect if the key is for a direct property / one level - ie key = 'firstName'):
public static PropertyInfo (this HtmlHelper htmlHelper, string key) {
PropertyInfo pInfo = htmlHelper.ViewData.Model.GetType().GetProperty(key);
return pInfo;
}
But is there a way for me to return the PropertyInfo based on a string alone
when Key equals something more complex, such as nested classes, objects, lists, etc...:
key = "somelist[0].myproperty"
key = "Items[0].someotherlist[1].someproperty" (where Items is defined as List<Item> Items {get; set;}, someotherlist is defined similarly)
Can the method be generic enough to essentially drill down as many levels as needed (defined)?
So here is what I came up with... this is about to get wordy, and mostly 'stream of thought'
I have custom HtmlHelperExtension, and within it :
PropertyInfo[] pInfoArray = htmlHelper.ViewData.Model.GetType().GetProperties();
PropertyInfo pInfo = GetPropertyInfo(pInfoArray, key);
This GetPropertyInfo() method takes the key, and the PropertyInfo array, cycles through the properties, until the keypart (using regex to remove any indication of an array from the string, so I am left with only the property) matches the property name. On Match, determine if this is the first cycle in the loop, and if so assign the matched property to my Temp Type and PropertyInfo variables. If keyParts are remaining to loop through, subsequent loops now use previously set temp variables and the for loop index [i] to iterate / drill down the class structure. Each time setting the pInfoTemp variable, and then pTypeTemp so the next loop can use where it left off.
private static PropertyInfo GetPropertyInfo(PropertyInfo[] pInfoArray, string key)
{
PropertyInfo pInfo = null;
string[] keyParts = key.Split('.');
Regex arrayRgx = new Regex("\\[\\d*\\]");
PropertyInfo pInfoTemp = null;
Type pTypeTemp = null;
foreach (PropertyInfo prop in pInfoArray)
{
string keyPartsTrimmed = arrayRgx.Replace(keyParts[0], ""); // removes '[#]' from string
if (keyPartsTrimmed == prop.Name) // match property name
{
for (int i = 0; i < keyParts.Count(); i++)
{
if (i == 0) // initial item [0]
{
pTypeTemp = prop.PropertyType; // gets [0]'s type
pInfoTemp = prop; // assigns [0]'s property info
}
else
{
pInfoTemp = GetNestedPropertyInfo(pTypeTemp, arrayRgx.Replace(keyParts[i], "")); // gets [i]'s property info for return or next iteration
pTypeTemp = pInfoTemp.PropertyType; // gets [i]'s type for next iteration
}
}
pInfo = pInfoTemp;
break;
}
}
return pInfo;
}
This next method is invoked by the previous for grabbing nested property info, more importantly for detecting whether the passedItemType is a List (without this, it fails to work correctly as it is unable to find the property asked for in a List<> Type. I need to know what the List item Type is.
private static PropertyInfo GetNestedPropertyInfo(Type passedItemType, string passedProperty)
{
PropertyInfo pInfoOut = null;
if (passedItemType.IsGenericType && passedItemType.GetGenericTypeDefinition() == typeof(List<>))
{
Type itemType = passedItemType.GetGenericArguments()[0];
pInfoOut = itemType.GetProperty(passedProperty);
}
else
{
pInfoOut = passedItemType.GetProperty(passedProperty);
}
return pInfoOut;
}
This currently suits my requirements as they are today, and I have tested it with the following properties, lists, subclasses, subclasses with lists, etc.. to 4 levels deep, but should function properly no matter the depth:
firstName
lastName
Items[1].sprocket
subClass.subClassInt
subClass.mySubClassObj.sprocketObj
subClass.ItemsInMySubClass[1].sprocket
subClass.ItemsInMySubClass[0].mySubClassObj.widgetObj
subClass.ItemsInMySubClass[2].mySubClassObj.sprocketObj
If anyone has a better solution, or see any potential issues with what I have, I welcome the feedback.
The best way in your case is to make a parser that split that expression.
What is the best practice in Dart when dealing with classes as data records?
To Elaborate: When writing an app, it is likely that a class for a table row will be created. As in
class Item { int itemid, String itemName, double score }
Item item = new Item();
This allows compile time catching of any typos etc. in Dart. (Unlike using a class that relies on NoSuchMethod.)
It will also need a corresponding string structure to bind to the HTML such as
<input id="itemname" type="text" bind-value="itemEdit.itemName">
So the Dart would be:
class ItemEdit { String itemId, String itemName, String score }
ItemEdit itemEdit = new ItemEdit();
Next we need a way to get from one to the other, so we add a method to Item
fromStrings(ItemEdit ie) {
itemid = ie.itemId == null ? null : int.parse(ie.itemId);
itemName = ie.ItemName;
score = ie.score == null ? null : double.parse(ie.score);
}
And the other way around:
toStrings(ItemEdit ie) {
ie.itemid = itemId == null ? '' : ie.itemId.toString();
ie. itemName = itemName == null ? '' : itemname; // Web_ui objects to nulls
ie.score = score == null ? null : score.toStringAsFixed(2);
}
Also, we get jason data from a database, so we need to add another method to Item:
fromJson(final String j) {
Map v = JSON.parse(j);
itemid = v['itemid'];
itemname = v['itemname'];
score = v['score'];
}
And we need to be able to revert to default values:
setDefaults() { itemId = 0; itemName = "New item"; score = 0; }
This verbosity gets me feeling like I am writing COBOL again!
There is something fundamental missing here - either in my understanding, or in the Dart/WebUI libraries.
What I would like to write is something like
class Item extends DataRecord {
int itemid = 0,
String itemName = 'New item',
double score = 0.0;
}
Then, without further coding, to be able to write code such as
item.toStrings();
...
item.fromStrings();
...
item.fromJson(json);
...
item.setDefaults(); // results in {0,'New item',0.0}
And to be able to write in the HTML:
value="{{item.strings.score}}"
If this was possible, it would be quicker, simpler, clearer, and less error prone than the code I am writing at the moment.
(Full disclosure, this answer is written with the assumption that at least one bug will be fixed. See below)
Three suggestions that might help.
Use named constructors to parse and create objects.
Take advantage of toJson() when encoding to JSON.
Use bind-value-as-number from Web UI
1) Named constructors
import 'dart:json' as json;
class Item {
int itemid;
String itemName;
double score;
Item.fromJson(String json) {
Map data = json.parse(json);
itemid = data['itemid'];
itemName = data['itemName'];
score = data['score'];
}
}
2) Encoding to JSON
The dart:json library has a stringify function to turn an object into a JSON string. If the algorithm encounters an object that is not a string, null, number, boolean, or collection of those, it will call toJson() on that object and expect something that is JSON-encodable.
class Item {
int itemid;
String itemName;
double score;
Map toJson() {
return {'itemid':itemid, 'itemName':itemName, 'score':score};
}
}
3) Now, having said that, sounds like you want to easily bind to HTML fields and get primitive values back, not just strings. Try this:
<input type="number" min="1" bind-value-as-number="myInt" />
(Note, there seems to be a bug with this functionality. See https://github.com/dart-lang/web-ui/issues/317)
(from https://groups.google.com/a/dartlang.org/forum/#!topic/web-ui/8JEAA5OxJOc)
Just found a way to perhaps help a little in the this situation:
class obj {
int gapX;
String get gapXStr => gapX.toString();
set gapXStr(String s) => gapX = int.Parse(s);
...
Now, from the HTML you can use, for example
bind-value="gapXStr"
and in code you can use
x += ob.gapX;
I just discovered a very strange behaviour. I have a class with a string property. In the setter of this property I compare the old value with the new value first and only change property if the values differ:
set
{
if ((object.ReferenceEquals(this.Identifier, value) != true))
{
this.Identifier = value;
this.RaisePropertyChanged("Identifier");
}
}
But this ReferenceEquals almost always returns false! Even if I call object.ReferenceEquals("test", "test") in Quick Watch I get false.
How is this possible?
That's because strings are immutable in C#:
The contents of a string object cannot
be changed after the object is
created, although the syntax makes it
appear as if you can do this.
Since you can't modify an existing string reference, there's no benefit in reusing them. The value passed to your property setter will always be a new string reference, except maybe if you do this.Identifier = this.Identifier;.
I'll try to clarify with an example:
string s = "Hello, "; // s contains a new string reference.
s += "world!"; // s now contains another string reference.