c# selecting from list with lambda expression

Question

I have a list of my entities and I'm using Select to get some properties from my entity. My entity has a PrimaryContact property and this has a LastNameproperty. So If I use like this it's working fine

var b = items.Select(s => s[PropertyName]); //Property name is "PrimaryContact" it's fine.

but If I use "PrimaryContact.LastName" this is not working

var x = items.Select(s => s[PropertyName]); //Property name is "PrimaryContact.LastName" it's not working

PropertyName might be evrything: "PrimaryContact.LastName", "PrimaryContact.FirstName", "PrimaryContact.Address.City"

Could someone help me on that please.

so what do you expect all the property like FirstName, City etc ? — Mostafiz
– Mostafiz, Commented Aug 13, 2016 at 10:35
@AhrorKayumov Accessing a property by name using indexer is not a standard "entity" operation. You'd better post the implementation of the indexer. — Ivan Stoev
– Ivan Stoev, Commented Aug 13, 2016 at 10:44

Mostafiz · Accepted Answer · 2016-08-13 10:38:53Z

1

If you want only one items LastName then

var x = items.Select(s => s["PrimaryContact"]).FirstOrDefault().LastName;

And if you want all items Lastname as collection then

var x = items.Select(s => s["PrimaryContact"].LastName);

if you want all the property then first select with all the property then iterate over it

ar x = items.Select(s => s["PrimaryContact"]);

foreach(var p in x)
 {
    // P.FirstName
    // p.LastName
    // p.Address.City
 }

edited Aug 13, 2016 at 10:38

answered Aug 13, 2016 at 10:15

Mostafiz

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3 Comments

Ahror Kayumov Over a year ago

why I cant use var x = items.Select(s => s["PrimaryContact.LastName"]);

Mostafiz Over a year ago

because seems PrimaryContact.LastName not collection of last name its a single entity but PrimaryContact is collection so you can select them using linq, but why do you this my solution is not best way ?

Ahror Kayumov Over a year ago

because PropertyName might be anything in my case not only PrimaryContact. PrimaryContact, PrimaryContact.LastName (FirstName ...). Category, Category.Name...

Gilad Green · Accepted Answer · 2016-08-13 10:24:31Z

0

Try this,

var x = items.Select(s => s["PrimaryContact"].LastName);

edited Aug 13, 2016 at 10:24

Gilad Green

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answered Aug 13, 2016 at 10:13

Sajeetharan

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2 Comments

Gilad Green Over a year ago

Unfortunately this will not compile because Select will return IEnumerable<HisEntity> and not a single one - so you cant]'t .LastName

Sajeetharan Over a year ago

@GiladGreen agreed

Sebastian Brosch · Accepted Answer · 2017-09-29 16:41:16Z

0

Select returns IEnumerable so if you want all the LastNames in items then:

var b = items.Select(s => s["PrimaryContact"].LastName);

Otherwise if you want only of one of them then after the Select use FirstOrDefault:

var b = items.Select(s => s["PrimaryContact"]).FirstOrDefault().LastName;

edited Sep 29, 2017 at 16:41

Sebastian Brosch

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answered Aug 13, 2016 at 10:15

Gilad Green

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