In a WinForms ReactiveUI ViewModel I have a property with a property setter that can throw an ArgumentException:
public string Foo
{
get { return _foo; }
set
{
if (value == "ERR" ) throw new ArgumentException("simulate an error");
this.RaiseAndSetIfChanged(ref _foo, value);
Debug.WriteLine(string.Format("Set Foo to {0}", _foo));
}
}
private string _foo;
In View the property Foo is bind to a textbox uiFoo:
this.Bind(ViewModel, vm => vm.Foo, v => v.uiFoo.Text);
Binding works properly (as shown by the output of the setter’s Debug.WriteLine).
But after typing “ERR” which throws ArgumentException the binding no longer works.
What solution do I have to bring back (or keep) binding in working state after the exceptions in setter ?
As we've mentioned in the comments on your question, exceptions inside property getter or setters is a BIG NO, NO.
Here are two solutions available to you: Either handle the invalid value when you try to read it or use a setter method. I would much prefer the latter; especially as you're throwing an ArgumentException, which should only be used when arguments are supplied. (Breaking this rule might be confusing for the consumer of the code: "Why am I getting an ArgumentException when I'm not calling any functions?")
Here's a way to do it:
public string Foo { get; private set; }
public void SetFoo(string value)
{
if(value == "invalid value")
thrown new ArgumentException($"{nameof(Foo)} can't be set to '{value}'", nameof(value));
Foo = value;
}
Related
Instead of checking every frame through the Update method, is there any event driven method to check if the value of an Enumerator as changed?
like:
public enum States{StateA, StateB,StateC};
States state;
void OnStateChanged(){
//do something..
}
Appreciate it.
You should use properties:
public enum States{StateA, StateB,StateC}
private States _state; //this holds the actual value
public States State { //this is public and accessible, and should be used to change "State"
get{
return _state;
}
set{
_state = value;
Debug.Log("Enum just got changed to: " + _state);
}
}
I have this very weird problem that I cannot get my head around. Perhaps someone could point out what I am doing wrong.
Basically, I am just trying to search items using Linq to Sitecore.
So, my classes look like ( I am using glass too)
[SitecoreType(TemplateId = "{TEMPLATE_GIUD}")]
public class MyMappedClass : SharedFieldClass
{
[SitecoreField(FieldName = "mylist")]
public virtual IEnumerable<SharedFieldClass> MyMultilistField { get; set; }
[SitecoreField(FieldName = "field1")]
[IndexField("field1")]
public virtual MyKeyValue field1 { get; set; }
}
[SitecoreType]
public class MyKeyValue
{
public virtual Sitecore.Data.ID Id {get;set;}
public virtual string MyValue{get;set;}
}
So when I do the below query it works as it's supposed to.
var results = context.GetQueryable<SearchResultItem>()
.Where(c => ((string)c["field1"]) == "{GUID}").GetResults();
But, when I do the below it returns 0 result.
List<MyMappedClass> results = context.GetQueryable<MyMappedClass>()
.Where(c => c.field1.MyValue == "{GUID}").ToList();
I have read this link . And I have followed the 2nd process described here for Glass to work with Sitecore7 Search (the "SharedFieldClass" contains all the basic index fields).
This is a pretty obvious scenario and I'm sure lots of people have done it already and I am doing something silly here.
Thanks in advance.
/## EDIT ##/
Okay so I've done a bit more digging on this. Not sure if it's a bug in ContentSearch/Luncene.NET API or I am missing something BUT seems like what was posted here is probably not TRUE and if you have a complex field type ( which you will ) you can not query with a mapped class against Lucene. ( not sure if this is also the case for Solr). If you are doing search against simple type like string and int then it works like a charm.
SO here're my findings:
After enabling DEBUG and LOG on for contentsearch I found that if I query like this context.GetQueryable<MyMappedClass>().Where(c => c.field1.MyValue == "{GUID}") what it gets translated into is DEBUG Executing lucene query: field1.value:7e9ed2ae07194d83872f9836715eca8e and as there's no such thing in the index named "field1.value" the query doesn't return anything. The name of the index is actually just "field1". Is this a bug ??
However, query like this context.GetQueryable<SearchResultItem>() .Where(c => ((string)c["field1"]) == "{GUID}").GetResults(); works because it gets translated into "DEBUG Executing lucene query: +field1:7e9ed2ae07194d83872f9836715eca8e".
I also did write a method in my mapped class like below:
public string this[string key]
{
get
{
return key.ToLowerInvariant();
}
set { }
}
Which allowed me write the below query with my MyMappedClass.
results2 = context.GetQueryable<MyMappedClass>().Where(c => c["filed1"]== "{GUID}").ToList();
This returned expected result. BUT the values of the fields in MyMappedClass are not filled ( in fact they're all null except the core/shared values like templateid, url etc which are populated in the filled document). So the result list are pretty much useless. I could do a loop over all of them and manually get the values populated as I have the itemid. But imagine the cost for a large result set.
Lastly I did this:
<fieldType fieldTypeName="droplink" storageType="YES" indexType="TOKENIZED" vectorType="NO" boost="1f" type="System.String" settingType="Sitecore.ContentSearch.LuceneProvider.LuceneSearchFieldConfiguration, Sitecore.ContentSearch.LuceneProvider" />
So this returned populated "field1" with the itemid in lucene query using "IndexViewer2.0". BUT this fails for MyMappedClass too as the value of "field1" in the document is a System.string .. but it is mapped as "MyKeyValue" in MyMappedClass SO it throws the below exception
Exception: System.InvalidCastException
Message: Invalid cast from 'System.String' to 'MyLib.MyKeyValue'.
SO, the big question is:
How does one query using his/her mapped class using the cool ContentSearch API ?
I bit more further digging got me to a working solution. Posting it here just in case anyone runs into this issue.
This is how my "SharedFieldClass" looked like ( which was somewhat wrong )
public abstract class SharedFieldClass
{
[SitecoreId]
[IndexField("_id")]
[TypeConverter(typeof(IndexFieldIDValueConverter))]
public virtual ID Id { get; set; }
[SitecoreInfo(SitecoreInfoType.Language)]
[IndexField("_language")]
public virtual string Language { get; set; }
[SitecoreInfo(SitecoreInfoType.Version)]
public virtual int Version
{
get
{
return Uri == null ? 0 : Uri.Version.Number;
}
}
[TypeConverter(typeof(IndexFieldItemUriValueConverter))]
[XmlIgnore]
[IndexField("_uniqueid")]
public virtual ItemUri Uri { get; set; }
}
And there's a class in Glass that does the mapping. Which looks like below:
var sitecoreService = new SitecoreService("web");
foreach (var r in results)
{
sitecoreService.Map(r);
}
for me this class was failing to map because of this line:
[SitecoreId]
[IndexField("_id")]
[TypeConverter(typeof(IndexFieldIDValueConverter))]
public virtual ID Id { get; set; }
It was throwing a NULL exception at sitecoreService.Map(r); line
So I changed it to below:
[SitecoreId]
[IndexField("_group")]
[TypeConverter(typeof(IndexFieldIDValueConverter))]
public virtual ID Id { get; set; }
And it worked. I'm not sure when the index field for ItemId in sitecore changed from "_id" to "_group" or whether it was always like that. But it is "_group" in the SearchResultItem class. So I used it and mapping was successful.
So to Sum it all the solution looks like this:
The Mapped Class:
[SitecoreType(TemplateId = "{TEMPLATE_GIUD}")]
public class MyMappedClass : SharedFieldClass
{
[SitecoreField(FieldName = "mylist")]
public virtual IEnumerable<SharedFieldClass> MyMultilistField { get; set; }
[SitecoreField(FieldName = "field1")]
[IndexField("field1")]
public virtual MyKeyValue field1 { get; set; }
// Will be set with key and value for each field in the index document
public string this[string key]
{
get
{
return key.ToLowerInvariant();
}
set { }
}
}
[SitecoreType]
public class MyKeyValue
{
public virtual Sitecore.Data.ID Id {get;set;}
public virtual string MyValue{get;set;}
}
And the query is:
List<MyMappedClass> results = context.GetQueryable<MyMappedClass>()
.Where(c => c["field1"] == "{GUID}").ToList();
That's it.
/* edited */
OH!! Wait that's not it. This will still fail to cast the complex type "MyKeyValue" when the "field1" is populated with guid in the index document.
So to avoid this I had to write my custom converter as #Michael Edwards suggested.
I had to modify the class slightly to fit my needs ..
public class IndexFieldKeyValueModelConverter : TypeConverter
{
public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
{
var config = Glass.Mapper.Context.Default.GetTypeConfiguration<SitecoreTypeConfiguration>(sourceType, true);
if (config != null && sourceType == typeof(MyLib.IKeyValue))
{
return true;
}
else
return base.CanConvertFrom(context, sourceType);
}
public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
{
if (destinationType == typeof(string))
return true;
else
return base.CanConvertTo(context, destinationType);
}
public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
{
var scContext = new SitecoreContext();
Guid x = Guid.Empty;
if(value is string)
{
x = new Guid((string)value);
}
var item = scContext.Database.GetItem(x.ToString());
if (item == null)
return null;
return scContext.CreateType(typeof(MyLib.IKeyValue), item, true, false, new Dictionary<string, object>());
}
public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
{
var config = Glass.Mapper.Context.Default.GetTypeConfiguration<SitecoreTypeConfiguration>(value.GetType(), true);
ID id = config.GetId(value);
return id.ToShortID().ToString().ToLowerInvariant();
}
}
Not sure if it were the expected behaviour or not .. but for some reason, in the convertfrom method the value of the "object value" parameter was short string id format. So for scContext.Database.GetItem to work I had to convert it to a proper GUID and then it started returning proper item rather than null.
AND then I wrote my query like this:
results = context.GetQueryable<MyMappedGlassClass>().Where(c => c["field1"] == field1value && c["field2"] == field2value && c["_template"] == templateId).Filter(selector => selector["_group"] != currentId).ToList();
Looks like a fair bit of work to get it to work. I guess using the LinqHelper.CreateQuery method is the easy way out .. but as Mr. Pope suggested here that this method is not be used as this is an internal method.
Not sure what's the balance here.
/* end edited */
Please see my question description section for explanation on why I had to do things this way.
Also, (I bias opinion ) is the trick described here may not be valid anymore (please see my question description's edit section for the reason behind).
Also, index field for itemid in the Glass Mapper tutorial here is I think wrong (unless otherwise proven).
Hope it helps someone saving/wasting time.
You could create a custom field mapper for lucene that would convert from the Guid in the index to a glass model. I hacked this out but I haven't tested it:
public class IndexFieldDateTimeValueConverter : TypeConverter
{
public Type RequestedType { get; set; }
public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
{
var config = Glass.Mapper.Context.Default.GetTypeConfiguration<SitecoreTypeConfiguration>(sourceType, true);
if (config != null)
{
RequestedType = sourceType;
return true;
}
else
return base.CanConvertFrom(context, sourceType);
}
public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
{
if (destinationType == typeof(string))
return true;
else
return base.CanConvertTo(context, destinationType);
}
public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
{
var scContext = new SitecoreContext();
return scContext.CreateType(RequestedType, scContext.Database.GetItem(value.ToString()),true, false, new Dictionary<string, object>());
}
public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
{
var config = Glass.Mapper.Context.Default.GetTypeConfiguration<SitecoreTypeConfiguration>(value.GetType(), true);
ID id =config.GetId(value);
return id.ToShortID().ToString().ToLowerInvariant();
}
My concern is that the ConvertFrom method does not get passed the type requested so we have to store this as property on the class to pass it from the CanConvertFrom method to the ConvertFrom method. This makes this class not thread safe.
Add this to the indexFieldStorageValueFormatter section of the sitecore config.
The problem here is that SearchResultItem is not actually an Item, but does have the GetItem() method to get the Sitecore item. What you need to do is the following:
List<MyMappedClass> results = context.GetQueryable<SearchResultItem>()
.Select(sri => sri.GetItem())
.Where(i => i != null)
.Select(i => i.GlassCast<MyMappedClass>())
.Where(c => c.field1.MyValue == "{GUID}").ToList();
I haven't worked with Glass specifically, but if you change your parent class to SearchResultItem, does it begin working? If so, that would indicate an issue with the SharedFieldClass parent class.
Consider this simple controller:
Porduct product = new Product(){
// Creating a product object;
};
try
{
productManager.SaveProduct(product);
return RedirectToAction("List");
}
catch (Exception ex)
{
ViewBag.ErrorMessage = ex.Message;
return View("Create", product);
}
Now, in my Create view, I want to check ViewBag object, to see if it has Error property or not. If it has the error property, I need to inject some JavaScript into the page, to show the error message to my user.
I created an extension method to check this:
public static bool Has (this object obj, string propertyName)
{
Type type = obj.GetType();
return type.GetProperty(propertyName) != null;
}
Then, in the Create view, I wrote this line of code:
#if (ViewBag.Has("Error"))
{
// Injecting JavaScript here
}
However, I get this error:
Cannot perform runtime binding on a null reference
Any idea?
#if (ViewBag.Error!=null)
{
// Injecting JavaScript here
}
Your code doesnt work because ViewBag is a dynamic object not a 'real' type.
the following code should work:
public static bool Has (this object obj, string propertyName)
{
var dynamic = obj as DynamicObject;
if(dynamic == null) return false;
return dynamic.GetDynamicMemberNames().Contains(propertyName);
}
Instead of using the ViewBag, use ViewData so you can check for the of the item you are storing. The ViewData object is used as Dictionary of objects that you can reference by key, it is not a dynamic as the ViewBag.
// Set the [ViewData][1] in the controller
ViewData["hideSearchForm"] = true;
// Use the condition in the view
if(Convert.ToBoolean(ViewData["hideSearchForm"])
hideSearchForm();
I would avoid ViewBag here completely.
See my thoughts here on this:
http://completedevelopment.blogspot.com/2011/12/stop-using-viewbag-in-most-places.html
The alternative would be to throw a custom error and catch it. how do you know if the database is down, or if its a business logic save error? in the example above you just catch a single exception, generally there is a better way to catch each exception type, and then a general exception handler for the truly unhandled exceptions such as the built in custom error pages or using ELMAH.
So above, I would instead
ModelState.AddModelError()
You can then look at these errors (assuming you arent jsut going to use the built in validation) via
How do I access the ModelState from within my View (aspx page)?
So please carefully consider displaying a message when you catch 'any' exception.
You can use ViewData.ContainsKey("yourkey").
In controller:
ViewBag.IsExist = true;
In view:
if(ViewData.ContainsKey("IsExist")) {...}
I need to test this but:
#if (ViewBag.ABoolParam ?? false)
{
//do stuff
}
I think will give you either the value of the ViewBag property, or return a default value if missing.
I´m building a Windows Forms aplication using LINQ to SQL. I´m using the auto generated code from the
dbml file.
Visual studio generated this code for the CNPJ property from my table:
[global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_CNPJ", DbType="VarChar(20) NOT NULL", CanBeNull=false)]
public string CNPJ
{
get
{
return this._CNPJ;
}
set
{
if ((this._CNPJ != value))
{
this.OnCNPJChanging(value);
this.SendPropertyChanging();
this._CNPJ = value;
this.SendPropertyChanged("CNPJ");
this.OnCNPJChanged();
}
}
}
and what I wanted is this:
[global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_CNPJ", DbType="VarChar(20) NOT NULL", CanBeNull=false)]
public string CNPJ
{
get
{
return APPLY_FORMAT(this._CNPJ);//Changed here
}
set
{
if ((this._CNPJ != value))
{
this.OnCNPJChanging(value);
this.SendPropertyChanging();
this._CNPJ = REMOVE_FORMAT(value); /// Changed here
this.SendPropertyChanged("CNPJ");
this.OnCNPJChanged();
}
}
}
But I will lose this changes when the code is re-generated.
Question is: what is the right way to accomplish this behavior (inherit and override, capture change event, other ) ?
if you´re curious, CNPJ is the brazilin business identification number, provided by the government.
Rather than trying to change the existing property, create a new property.
public partial class YourClass
{
public string FORMATTED_CNPJ
{
get
{
return APPLY_FORMAT(this._CNPJ);
}
set
{
this.CNPJ = REMOVE_FORMAT(value);
}
}
}
If you don't want anyone to access the underlying CNPJ property you can set it to private in the designer (the access modifier combobox in the column properties window). You can even rename that property to _CNPJ, make it private, and then name your 'wrapper' property above CNPJ if you want to avoid any breaking changes.
LINQ to SQL creates the classes as partial classes. You can create another partial class in a different file but with the same class name and then you can change the behaviour.
public partial class YourClass
{
partial void OnCNPJChanged()
{
this._CNPJ = REMOVE_FORMAT(value);
}
}
See here for more information.
This is a question about style and design rather than syntax.
I have domain models that have several (for lack of a better term) navigation properties. So in my strongly typed details view of Foo which has a property of type Bar I could do the following:
<%: Foo.Bar.Name %>
However, sometimes Bar is Null, so I end up with something like:
<%: Foo.Bar == null ? String.Empty : Foo.Bar.Name %>
In other cases, because the convenience of the navigation properties I could do even more chaining. The downside, however, is the introduction of more null checking in my View.
As an alternative, I could do all the null checking in a ViewModel so that I've passed off something "clean" to the View. I'm looking for some ideas or common sense guidelines for avoiding excessive null checking in my views.
P.S. I'm using ASP.NET MVC, but I think this question may be relevant to other MVC frameworks.
You already answered it yourself:
As an alternative, I could do all the null checking in a ViewModel so that I've passed off something "clean" to the View.
That's it, use a ViewModel.
Not sure whether it really makes sense in your context, but when you are bothered by an excess of null-checks, you should contemplate the Null Object pattern.
Create a helper that checks for null and returns an appropriate default.
For example if you have a phone number field, you pass it the field and a constant PHONE. the helper checks if null and displays "No phone number Available" if it is null.
This way you keep all your null checking in one place.
One option is using a helper, as described here.
You could provide lazy initialization for your navigation properties in you model. That way you could minimize the risk of encountering null values.
public class Foo
{
private Bar _bar;
public Bar Bar
{
get
{
if (_bar == null)
{
_bar = new Bar();
}
return _bar;
}
}
}
public class Bar
{
public string Name { get; set; }
}
First consider whether in your model an instance of Foo is valid if Bar is null. If no then you should put a guard clause in the constructor and\or the setter of the Bar property.
public class Foo{
public BarClass _bar;
public BarClass Bar{
get{return _bar; }
set{
if(value == null)
throw new ArgumentNullException();
_bar = value; }
}
public Foo(BarClass bar){
if(bar == null) throw new ArgumentNullException();
_bar = bar;
}
}
Secondly, too many and duplicated null checks is a code smell. You should use the refactoring Replace Conditional with Polymorphism. You can create a Null object according to the Null Object Pattern. Then make sure that the Bar property is always initialized with NullBar.
public class Foo{
public BarClass _bar;
public BarClass Bar{
get{return _bar ?? new NullBar(); }
set{ _bar = value ?? new NullBar(); }
}
public Foo(){
Bar = new NullBar(); // initialization
}
}
Then Bar will never be null.