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Accepted
gbianchi
Asked: 2020-08-17 10:38:40 +0800 CST 2020-08-17 10:38:40 +0800 CST

How to transform a string into a list of objects?

  • 772

Problem:

I am parsing an XML , all that part works perfectly. One of the items is a string of names, separated by commas. What I want is a control that can bind to a class to set and unset the string, based on user selections.

Tests

The serialization and deserialization is automatic and works perfectly, but it obviously leaves me the result in a string. The class that serializes the XML has the interface INotifyPropertyChanged, working for all properties.

I create another class, which is supposed to be the one I'm going to bind to my control:

public class ListaMarcas: System.ComponentModel.INotifyPropertyChanged
{
    private bool bMarcado;
    private string sTexto;
    public event System.ComponentModel.PropertyChangedEventHandler PropertyChanged;
    public virtual void OnPropertyChanged(string propertyName)
    {
        System.ComponentModel.PropertyChangedEventHandler handler = this.PropertyChanged;
        if ((handler != null))
        {
            handler(this, new System.ComponentModel.PropertyChangedEventArgs(propertyName));
        }
    }
    public bool Marcado
    {
        get
        {
            return bMarcado;
        }
        set
        {
            if ((bMarcado.Equals(value) != true))
            {
                bMarcado = value;
                this.OnPropertyChanged("Marcado");
            }
        }
    }

    public string texto
    {
        get
        {
            return sTexto;
        }
        set
        {
            if ((sTexto.Equals(value) != true))
            {
                sTexto = value;
                this.OnPropertyChanged("texto");
            }

        }
    }
}

This class should fill an object ObservableCollectionfor the roundtrip to work. I do that on the class that serializes:

private ObservableCollection<ListaMarcas> pListaSistemas;

[XmlIgnore]
public ObservableCollection<ListaMarcas> ListaMarcas
{
    get
    {
        return pListaSistemas;
    }
    set
    {
        if ((pListaSistemas != null))
        {
            if ((pListaSistemas.Equals(value) != true))
            {
                pListaSistemas = value;
                this.OnPropertyChanged("select");
            }
        }
        else
        {
            pListaSistemas = value;
            this.OnPropertyChanged("select");
        }
    }
}

How do I make the string property fill itself, and be transformed into a valid list?

public consultaRestriccion restriccion
{
    get
    {
        return this.restriccionField;
    }
    set
    {
        if ((this.restriccionField != null))
        {
            if ((restriccionField.Equals(value) != true))
            {
                this.restriccionField = value;
                this.OnPropertyChanged("restriccion");
            }
        }
        else
        {
            this.restriccionField = value;
            this.OnPropertyChanged("restriccion");
        }
    }
}

Note that the code is automatically written from XSD2Code , so it is in a partial class.

The string comes in the format: "dato1,dato2,dato3", which makes it easy to transform it into a list by doing split. Where should I put that splitso that all objects are automatically kept up to date?

Edition

The view displays that string, as a list of checkboxes that the user can select or not, and the selected ones have to be the comma-separated string that is sent back to the XML.

c#

2 Answers

  1. Best Answer

    To solve this, what I did was create an event in the class ListaMarcasthat is executed every time a mark changes.

    ...
public event Action CambioUnCheck;
...
public bool Marcado
{
    get
    {
        return bMarcado;
    }
    set
    {
        if ((bMarcado.Equals(value) != true))
        {
            bMarcado = value;
            this.OnPropertyChanged("Marcado");
            CambioUnCheck?.Invoke();
        }
    }
}

    The call CambioUnCheck?.Invoke();is a simplification to check that CambioUnCheckit is not null before doing the invoke.

    The object pListaSistemasstays the same, but when I fill it with objects of type ListaMarcas, I also declare a function that is going to be the receiver of the event:

    public void HacerCambioDeCheck()
{
....
}

    And when filling the list I do something like this:

    ObjetoTemporal = new ListaMarcas { Chequeado = false, Texto = "1" };
ObjetoTemporal.CambioUnCheck += HacerCambioDeCheck;
ListaSistema.Add(ObjetoTemporal);

    The only problem is that on the first load, the event is executed every time I load the list for the first time. To avoid problems with that, add a variable in the class:

    private bool EvitarEvento = true;

    and in the event receiver add:

    public void HacerCambioDeCheck()
{
    if (EvitarEvento)
        return;
    ...
}

    In this way, in the first load I leave AvoidEvent to true, and then I leave it to false so the event is executed on each change.

    What the function HacerCambioDeCheckdoes is reload the string in the model, with each change of a checkbox.

    • 4

  2. It might help to add a new attribute in the MarkList class with a method that transforms the string stext attribute into a list.

    private List<String> ldatos;

public List<String> lista
{
    get
    {
        return ldatos;
    }
    set
    {
        ldatos = split(stexto)
    }
}
    • 0