Xamarin Binding from List, query List in c#

Question

If´ve got a xaml-view, which gets some values from a list (from a DB throw a rest-service). so there are some parameters like "id", "phone number" or "adress". Evrybody has an ID, sometimes a phoneNo, sometimes Address or both. now i want to view a list, with the ID, but only with "people" which has got an phone number. that for, i´ve got a listview, in which i´m binding the phone number f.e.:

 ...<viewcell x:Name="people">
                                    <Label Text="ID: "/>
                                    <Label Text="{Binding ID}"/>                                        
                                    <Label Text="PhoneNo: "/>
                                    <Label Text="{Binding PhoneNr}"/>
  </viewcell>...

this is where i set the itemsource:

        people.ItemsSource = retList;

so, as you can see, i will get a list, where all people are listed, sometimes there are phonenumbers, sometimes this field is empty. but i wonly want the peoble with an phonenumber in my list. is this possible? thanks a lot

Miamy · Accepted Answer · 2018-12-12 15:05:26Z

1

Use this:

var phonesList = retList.Where(p => !string.IsNullOrEmpty(p.PhoneNr)).ToList();

answered Dec 12, 2018 at 15:05

Miamy

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5 Comments

S Kirchner Over a year ago

ah damn i ha´ve to ask it in a other way: everybody has got a phonenr, but some are german numbers(+49) and some are swiss numbers (+41) for example. so i´ve got an other value which says "pre-number". so i want only the people, where the pre-no is a swiss one

Miamy Over a year ago

But the answer will be almost the same except used condition: var phonesList = retList.Where(p => (p.PhoneNr!= null && p.PhoneNr.StartsWith("(+49)"))).ToList();. In every case you will obtain a new list based on existing one under some condition. Am I right this is your goal?

S Kirchner Over a year ago

okay thanks a lot. there´s still a little error: in my case, the "phoneNr" is a type of a enum. so it says, there is not the posibility of "StartsWith(...)"

Miamy Over a year ago

Yes, StartsWith is intended for strings. So you should use something like ...&& p.PhoneNr == YourDesiredValue.

S Kirchner Over a year ago

as a string doesnt work.. it´s called Pre_number in my case. so it should be something like: where peoble.pre_number == +49

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