I've seen question ReactiveUI: Using CanExecute with a ReactiveCommand, however my issue is that I have a string property, UniqueID, and I want it to only execute when it has a length equal to 7. I cannot seem to come up with an observer that doesn't crash the program. What is the correct simple way to do this?
public class MainViewModel : ReactiveValidatedObject
{
public MainViewModel()
{
RetrieveRecord = new ReactiveAsyncCommand(/* what goes here for CanExecute */);
RetrieveRecord.Subscriber(x => Record = new Record(UniqueId));
// or do we use the method RetrieveRecord.CanExecute()?
// the next line crashes the app
RetrieveRecord.CanExecute(UniqueId.Length == 7);
}
public ReactiveAsyncCommand RetrieveRecord { get; private set; }
string _uniqueId;
public string UniqueId
{
get { return _uniqueId; }
set
{
_clientId = value;
this.RaisePropertyChanged(x => x.UniqueId);
}
}
}
How about:
RetrieveRecord = new ReactiveAsyncCommand(
this.WhenAny(x => x.UniqueId, x => x.Value.Length == 7));
Related
I'm working on a Xamarin Forms project. I have a very simple page where a job seeker searches job posts by entering a location(ex. New York) and a radius(picker). I have the following code in my PageViewModel:
public class SearchPageViewModel : BaseViewModel
{
private readonly INavigation _navigation;
private readonly GooglePlacesApiService _api;
private IEnumerable<JobPost> Posts;
public int RadiusIndex {get;set;}
public SearchPageViewModel (INavigation navigation, IEnumerable<JobPost> posts)
{
_navigation = navigation;
var settings = GoogleApiSettings.Builder.WithApiKey("MY_API_KEY").Build();
_api = new GooglePlacesApiService(settings);
this.posts =posts;
}
public ICommand DoSearchCommand
=> new Command(async () => await DoSearchAsync().ConfigureAwait(false), () => CanSearch);
public ICommand SelectItemCommand
=> new Command<Prediction>(async (prediction) =>
{
//!!!Filter jobposts based on position and radius to be able to display it!!!
_api.ResetSessionToken();
});
private string _searchText;
public string SearchText
{
get => _searchText;
set
{
if (SetProperty(ref _searchText, value))
OnPropertyChanged("CanSearch");
}
}
private List<Prediction> _results;
public List<Prediction> Results
{
get => _results;
set => SetProperty(ref _results, value);
}
public bool CanSearch => !string.IsNullOrWhiteSpace(SearchText) && SearchText.Length > 2;
private async Task DoSearchAsync()
{
var results = await _api.GetPredictionsAsync(SearchText)
.ConfigureAwait(false);
if(results != null && results.Status.Equals("OK"))
{
ResultCount = results.Items.Count;
Results = results.Items;
OnPropertyChanged("HasResults");
}
}
}
public class JobPost
{
public Position Location {get;set;}
}
Ok, so far it works well. Once the search button is clicked the job seeker get a list of predictions and picks a place. But the problem is now, how do I get the positioning(longitude and latitude) of the picked prediction, so I can filter the job posts so I can dsiplay the result to the job seeker.
Thanks in advance.
use the Essentials GeoCoding plugin
var address = "New York";
var locations = await Geocoding.GetLocationsAsync(address);
locations will be a list of potential matches, each with a lat/long
var location = locations?.FirstOrDefault();
if (location != null)
{
Console.WriteLine($"Latitude: {location.Latitude}, Longitude: {location.Longitude}, Altitude: {location.Altitude}");
}
I tried this solution: Custom fields with FormBuilder in the Microsoft Bot Framework
But failed to get it working....The problem I encountered is that when I assign the base.Form = value, the _prompt in the _field gets a default recognizer, and it won't get overriden in the next line's SetRecognizer call, that only replaces the _field's recognizer.
However the matching process uses the _prompt's recognizer internally ( ? ).
Here is my code:
public class LuisIntentRecognizer<T> : RecognizePrimitive<T>
where T : class
{
public LuisIntentRecognizer(IField<T> field, string luisModelID, string luisSubscriptionKey)
: base(field)
{
_luisModelID = luisModelID;
_luisSubscriptionKey = luisSubscriptionKey;
}
public override DescribeAttribute ValueDescription(object value)
{
return new DescribeAttribute((string)value);
}
public override IEnumerable<string> ValidInputs(object value)
{
yield return (string)value;
}
public override TermMatch Parse(string input)
{
TermMatch result = null;
if (!string.IsNullOrWhiteSpace(input))
{
var luisModel = new LuisModelAttribute(_luisModelID, _luisSubscriptionKey);
var luisService = new LuisService(luisModel);
var luisResult = luisService.QueryAsync(input).Result; // TODO refactor somehow to async
var winner = luisResult.Intents.MaxBy(i => i.Score ?? 0d);
if (winner != null && !string.IsNullOrEmpty(winner.Intent))
{
result = new TermMatch(0, winner.Intent.Length, 0.0, winner.Intent);
}
else
{
result = new TermMatch(0, input.Length, 0.0, input);
}
}
return result;
}
public override string Help(T state, object defaultValue)
{
var prompt = new Prompter<T>(_field.Template(TemplateUsage.StringHelp), _field.Form, null);
var args = HelpArgs(state, defaultValue);
return prompt.Prompt(state, _field.Name, args.ToArray()).Prompt;
}
private string _luisModelID;
private string _luisSubscriptionKey;
}
public class LuisIntentField<T> : FieldReflector<T>
where T : class
{
public LuisIntentField(string name, string luisModelID, string luisSubscriptionKey, bool ignoreAnnotations = false)
: base(name, ignoreAnnotations)
{
_luisModelID = luisModelID;
_luisSubscriptionKey = luisSubscriptionKey;
}
public override IForm<T> Form
{
set
{
base.Form = value;
base.SetRecognizer(new LuisIntentRecognizer<T>(this, _luisModelID, _luisSubscriptionKey));
}
}
private string _luisModelID;
private string _luisSubscriptionKey;
}
Could anyone get it working?
Thanks
It seems to be a bug in the framework indeed: https://github.com/Microsoft/BotBuilder/issues/879
Background:
I have created a function import which is available in my context object as GetJournalViewItemsQuery()
The function import returns a complex type called JournalViewItem.
Now when I try to load the JournalViewItem into my application DTO called JournalEntry I come up with error:
Error 7 Cannot implicitly convert type 'MyApp.Infrastructure.Models.JournalEntry' to 'MyApp.SqlData.JournalViewItem'
This is the code:
var journalEntry = Context.GetJournalViewItemsQuery()
.Where(i => i.JournalItemId == _journalEntryId)
.Select(x => new JournalEntry(x.JournalItemId,
x.HeaderText,x.JournalText, x.LastUpdatedOn,
x.JournalItemTypeId)).Single();
The error happens at the "new JournalEntry" line.
My question: How can I cast the JournalViewItem complex type to my DTO ?
Thank you
After #JanR suggestion I still have the same problem. The modified code is:
var journalEntry = Context.GetJournalViewItemsQuery()
.Where(i => i.JournalItemId == _journalEntryId)
.Select(x => new JournalEntry
{
JournalEntryNumber = x.JournalItemId,
HeaderText = x.HeaderText,
BodyText = x.JournalText,
LastUpdatedOn = x.LastUpdatedOn,
JournalEntryType = x.JournalItemTypeId
}).Single();
I found out the reason for my problem. I failed to mention (my apologies) that I'm working off generated code from WCF RIA Domain Services for Silverlight application. As such the Context.GetJournalViewItemsQuery() needs to be executed and THEN I can query the results on my callback method using the LINQ expression that #Chuck.Net and JanR have suggested.
Here's the working code to those who might be interested:
public IList<JournalEntryHeader> GetJournalEntryHeaders()
{
PerformQuery<JournalViewItem>(Context.GetJournalViewItemsQuery(), GetJournalEntryHeadersFromDbComplete);
return _journalHeaders;
}
void PerformJournalEntryHeadersQuery(EntityQuery<JournalViewItem> qry,
EventHandler<EntityResultsArgs<JournalViewItem>> evt)
{
Context.Load<JournalViewItem>(qry, r =>
{
if (evt != null)
{
try
{
if (r.HasError)
{
evt(this, new EntityResultsArgs<JournalViewItem>(r.Error));
}
else if (r.Entities.Count() > 0)
{
evt(this, new EntityResultsArgs<JournalViewItem>(Context.JournalViewItems));
}
else if (r.Entities.Count() == 0 && _currentJournalItemsPage > 0)
{
GetPrevPageJournalEntryHeadersAsync();
}
}
catch (Exception ex)
{
evt(this, new EntityResultsArgs<JournalViewItem>(ex));
}
}
}, null);
}
void GetJournalEntryHeadersFromDbComplete(object sender, EntityResultsArgs<JournalViewItem> e)
{
if (e.Error != null)
{
string errMsg = e.Error.Message;
}
else
{
_journalHeaders = e.Results
.Select(
x => new JournalEntryHeader(x.JournalItemId,
x.ProjectName,
x.TopicName,
x.HeaderText,
x.EntryTypeName,
x.LastUpdatedOn)).ToList();
GetJournalEntryHeadersComplete(this, new JournalEntryHeaderItemsEventArgs(_journalHeaders));
}
}
What you need to do is the following, in the new JournalEntry() function you will need to set all the properties to the JournalViewItem object.
var journalEntry = Context.GetJournalViewItemsQuery()
.Where(i => i.JournalItemId == _journalEntryId)
.Select(x => new JournalEntry {
JournalEntryId = x.JournalItemId,
HeaderText = x.HeaderText,
JournalText = x.JournalText
//etc
}).Single();
I am just guessing the actual property names here as I am not familiar with what the JounralEntry object looks like.
EDIT: added {}
I created a ConsoleApp to test #JanR answer. It seems to be working correctly.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace StackOverFlowConsoleApplication
{
class Program
{
static void Main(string[] args)
{
List<JournalViewItem> JournalViewItems = new List<JournalViewItem>()
{
new JournalViewItem(){JournalItemId =1, HeaderText="HeaderText", JournalText="JournalText", LastUpdatedOn= DateTime.Today, JournalItemTypeId=1},
};
int _journalEntryId = 1;
var journalEntry = JournalViewItems
.Where(i => i.JournalItemId == _journalEntryId)
.Select(x => new JournalEntry
{
JournalEntryNumber = x.JournalItemId,
HeaderText = x.HeaderText,
BodyText = x.JournalText,
LastUpdatedOn = x.LastUpdatedOn,
JournalEntryType = x.JournalItemTypeId
}).Single();
}
class JournalViewItem
{
public int JournalItemId { get; set; }
public string HeaderText { get; set; }
public string JournalText { get; set; }
public DateTime LastUpdatedOn { get; set; }
public int JournalItemTypeId { get; set; }
}
class JournalEntry
{
public int JournalEntryNumber { get; set; }
public string HeaderText { get; set; }
public string BodyText { get; set; }
public DateTime LastUpdatedOn { get; set; }
public int JournalEntryType { get; set; }
}
}
}
I looked into complx type a little bit. I tried the following code in my own project and was able to reproduce the error you mentioned:
var result = (from y in CS.PSMBIPMTTXLOGs select new PSMBIPMTCONTROL(){MBI_PMT_TX_ID = y.MBI_PMT_TX_ID}).ToList();
But when I changed it to return anonymous type, it worked:
var result = (from y in CS.PSMBIPMTTXLOGs select new {MBI_PMT_TX_ID = y.MBI_PMT_TX_ID}).ToList();
You mentioned that you have even tried creating an anonymous type instead of newing it into my DTO, but it still complains. Can you post your code for returning an anonymous type and the error message it gives? Thank you.
I found out the reason for my problem. I failed to mention (my apologies) that I'm working off generated code from WCF RIA Domain Services for Silverlight application. As such the Context.GetJournalViewItemsQuery() needs to be executed and THEN I can query the results on my callback method using the LINQ expression that #Chuck.Net and JanR have suggested.
You'll find the answer in the original post where I entered the question.
Trying to save selections from a CheckBoxList as a comma-separated list (string) in DB (one or more choices selected). I am using a proxy in order to save as a string because otherwise I'd have to create separate tables in the DB for a relation - the work is not worth it for this simple scenario and I was hoping that I could just convert it to a string and avoid that.
The CheckBoxList uses an enum for it's choices:
public enum Selection
{
Selection1,
Selection2,
Selection3
}
Not to be convoluted, but I use [Display(Name="Choice 1")] and an extension class to display something friendly on the UI. Not sure if I can save that string instead of just the enum, although I think if I save as enum it's not a big deal for me to "display" the friendly string on UI on some confirmation page.
This is the "Record" class that saves a string in the DB:
public virtual string MyCheckBox { get; set; }
This is the "Proxy", which is some sample I found but not directly dealing with enum, and which uses IEnumerable<string> (or should it be IEnumerable<Selection>?):
public IEnumerable<string> MyCheckBox
{
get
{
if (String.IsNullOrWhiteSpace(Record.MyCheckBox)) return new string[] { };
return Record
.MyCheckBox
.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries)
.Select(r => r.Trim())
.Where(r => !String.IsNullOrEmpty(r));
}
set
{
Record.MyCheckBox = value == null ? null : String.Join(",", value);
}
}
To save in the DB, I am trying to do this in a create class:
proxy.MyCheckBox = record.MyCheckBox; //getting error here
but am getting the error:
Cannot implicitly convert 'string' to System.Collections.Generic.IEnumerable'
I don't know, if it's possible or better, to use Parse or ToString from the API for enum values.
I know that doing something like this will store whatever I put in the ("") into the DB, so it's just a matter of figuring out how to overcome the error (or, if there is an alternative):
proxy.MyCheckBox = new[] {"foo", "bar"};
I am not good with this stuff and have just been digging and digging to come up with a solution. Any help is much appreciated.
You can accomplish this using a custom user type. The example below uses an ISet<string> on the class and stores the values as a delimited string.
[Serializable]
public class CommaDelimitedSet : IUserType
{
const string delimiter = ",";
#region IUserType Members
public new bool Equals(object x, object y)
{
if (ReferenceEquals(x, y))
{
return true;
}
var xSet = x as ISet<string>;
var ySet = y as ISet<string>;
if (xSet == null || ySet == null)
{
return false;
}
// compare set contents
return xSet.Except(ySet).Count() == 0 && ySet.Except(xSet).Count() == 0;
}
public int GetHashCode(object x)
{
return x.GetHashCode();
}
public object NullSafeGet(IDataReader rs, string[] names, object owner)
{
var outValue = NHibernateUtil.String.NullSafeGet(rs, names[0]) as string;
if (string.IsNullOrEmpty(outValue))
{
return new HashSet<string>();
}
else
{
var splitArray = outValue.Split(new[] {Delimiter}, StringSplitOptions.RemoveEmptyEntries);
return new HashSet<string>(splitArray);
}
}
public void NullSafeSet(IDbCommand cmd, object value, int index)
{
var inValue = value as ISet<string>;
object setValue = inValue == null ? null : string.Join(Delimiter, inValue);
NHibernateUtil.String.NullSafeSet(cmd, setValue, index);
}
public object DeepCopy(object value)
{
// return new ISet so that Equals can work
// see http://www.mail-archive.com/nhusers#googlegroups.com/msg11054.html
var set = value as ISet<string>;
if (set == null)
{
return null;
}
return new HashSet<string>(set);
}
public object Replace(object original, object target, object owner)
{
return original;
}
public object Assemble(object cached, object owner)
{
return DeepCopy(cached);
}
public object Disassemble(object value)
{
return DeepCopy(value);
}
public SqlType[] SqlTypes
{
get { return new[] {new SqlType(DbType.String)}; }
}
public Type ReturnedType
{
get { return typeof(ISet<string>); }
}
public bool IsMutable
{
get { return false; }
}
#endregion
}
Usage in mapping file:
Map(x => x.CheckboxValues.CustomType<CommaDelimitedSet>();
For simplicity sake lets assume I have the following two classes:
public class ComplexClass
{
public List<SubClass> SubClasses { get; set; }
public string Name { get; set; }
}
public class SubClass
{
public string Name { get; set; }
}
I have a List<ComplexClass> and I need to build a query based on some parameters.
It's an easy task if all I need to do is use the Name property of ComplexClass. Here's an example:
static IQueryable<ComplexClass> GetQuery(string someParameter, string someOtherParameter)
{
var query = list.AsQueryable();
if (!String.IsNullOrEmpty(someParameter))
query = query.Where(c => c.Name.StartsWith(someParameter));
if (!String.IsNullOrEmpty(someOtherParameter))
query = query.Where(c => c.Name.EndsWith(someOtherParameter));
return query;
}
Based on the parameters I have I can add more query elements. Of course the above example is simple, but the actual problem contains more parameters, and that number can grow.
Things aren't as simple if I want to find those ComplexClass instances which have SubClass instances which meet criteria based on parameters:
static IQueryable<ComplexClass> GetSubQuery(string someParameter, string someOtherParameter)
{
var query = list.AsQueryable();
if (!String.IsNullOrEmpty(someParameter))
if (!String.IsNullOrEmpty(someOtherParameter))
return query.Where(c => c.SubClasses.Where(sc => sc.Name.StartsWith(someParameter) && sc.Name.EndsWith(someOtherParameter)).Any());
else
return query.Where(c => c.SubClasses.Where(sc => sc.Name.StartsWith(someParameter)).Any());
else
if (!String.IsNullOrEmpty(someOtherParameter))
return query.Where(c => c.SubClasses.Where(sc => sc.Name.EndsWith(someOtherParameter)).Any());
else
return null;
}
I can no longer just add bits of the query based on each parameter, I now need to write the whole query in one go, and this means I need to check every combination of parameters, which is hardly ideal.
I suspect the key is to build an Expression class and create a lambda expression from that, but I'm not sure how to tackle the problem.
Any suggestions? :)
EDIT:
My initial idea was this:
static IQueryable<ComplexClass> GetSubQuery(string someParameter, string someOtherParameter)
{
var query = list.AsQueryable();
query = query.Where(c =>
{
var subQuery = c.SubClasses.AsQueryable();
if (!String.IsNullOrEmpty(someParameter))
subQuery = subQuery.Where(sc => sc.Name.StartsWith(someParameter));
if (!String.IsNullOrEmpty(someOtherParameter))
subQuery = subQuery.Where(sc => sc.Name.EndsWith(someOtherParameter));
return subQuery.Any();
});
return query;
}
This works in my small console test application as it's using LINQ to Objects. Unfortunately, I need to use Entity Framework and LINQ to Entities, which causes an implementation similar to the one above to throw a A lambda expression with a statement body cannot be converted to an expression tree error message.
I'm assuming that in you real-life code the SubClasses property is IQueryable<SubClass> rather than List<SubClass>?
If so, then your query building becomes easy:
static IQueryable<ComplexClass> GetSubQuery(
string someParameter, string someOtherParameter)
{
var query = list.AsQueryable();
if (!String.IsNullOrEmpty(someParameter))
query = query.Where(c => c.SubClasses
.Where(sc => sc.Name.StartsWith(someParameter)).Any());
if (!String.IsNullOrEmpty(someOtherParameter))
query = query.Where(c => c.SubClasses
.Where(sc => sc.Name.StartsWith(someOtherParameter)).Any());
return query;
}
Mixing IEnumerable<T> and IQueryable<T> using AsQueryable() is never a good idea.
I implemented my solution in a simple Console Project:
internal class Program
{
#region Constants and Fields
private static readonly List<ComplexClass> list = new List<ComplexClass>
{
new ComplexClass
{
Name = "complex",
SubClasses = new List<SubClass>
{
new SubClass
{
SubName = "foobar"
}
}
},
new ComplexClass
{
Name = "complex",
SubClasses = new List<SubClass>
{
new SubClass
{
SubName = "notfoobar"
}
}
}
};
#endregion
#region Public Methods
public static void Main(string[] args)
{
Console.WriteLine("foo / bar :");
GetSubQuery("foo", "bar");
Console.WriteLine();
Console.WriteLine("foo / null :");
GetSubQuery("foo", null);
Console.WriteLine();
Console.WriteLine("string.Empty / bar :");
GetSubQuery(string.Empty, "bar");
Console.WriteLine();
Console.WriteLine("maeh / bar :");
GetSubQuery("maeh", "bar");
Console.ReadKey();
}
#endregion
#region Methods
private static void GetSubQuery(string startsWith,
string endsWith)
{
var query = from item in list
let StartIsNull = string.IsNullOrEmpty(startsWith)
let EndIsNull = string.IsNullOrEmpty(endsWith)
where
(StartIsNull || item.SubClasses.Any(sc => sc.SubName.StartsWith(startsWith)))
&& (EndIsNull || item.SubClasses.Any(sc => sc.SubName.EndsWith(endsWith)))
select item;
foreach (var complexClass in query)
{
Console.WriteLine(complexClass.SubClasses.First().SubName);
}
}
#endregion
public class ComplexClass
{
#region Public Properties
public string Name { get; set; }
public List<SubClass> SubClasses { get; set; }
#endregion
}
public class SubClass
{
#region Public Properties
public string SubName { get; set; }
#endregion
}
}
The Console Output is:
foo / bar :
foobar
foo / null :
foobar
string.Empty / bar :
foobar
notfoobar
maeh / bar :