Linq Converting String to List

Question

Hi I am getting the following error with my Linq query.

Cannot implicitly convert type 'System.Collections.Generic.List<string>'
to 'System.Collections.Generic.List<CTS.Domain.OCASPhoneCalls>'

I know what it means, but I'm unsure how to fix it. Can someone help me with my query? I'm really new to linq.

public List<OCASPhoneCalls> getPhoneLogs2()
{
    using (var repo = new OCASPhoneCallsRepository(new UnitOfWorkCTS()))
    {
        List<OCASPhoneCalls> phone = repo.AllIncluding(p => p.OCASStaff)
            .Where(y => y.intNIOSHClaimID == null)
            .Select(w => w.vcharDiscussion.Substring(0, 100) + "...")
            .ToList();                  
        return phone;
    }
}

You are selecting a List<string> but you are declaring a List<OCASPhoneCalls> — Tim Schmelter
– Tim Schmelter, Commented Mar 7, 2014 at 15:32

Habib · Accepted Answer · 2014-03-07 15:31:42Z

6

You are selecting a single property with

.Select(w => w.vcharDiscussion.Substring(0, 100) + "...")

This would return you IEnumerable<string> and calling ToList would return you List<string> NOT List<OCASPhoneCalls>.

If you are returning formatted strings then your method return type should be List<string> like:

public List<string> getPhoneLogs2()
{
    using (var repo = new OCASPhoneCallsRepository(new UnitOfWorkCTS()))
    {
        List<string> phone = repo.AllIncluding(p => p.OCASStaff)
            .Where(y => y.intNIOSHClaimID == null)
            .Select(w => w.vcharDiscussion.Substring(0, 100) + "...")
            .ToList();                  
        return phone;
    }
}

answered Mar 7, 2014 at 15:31

Habib

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5 Comments

Tim Schmelter Over a year ago

I'm fairly sure that he wants to return the objects but shorten the text property if necessary.

Habib Over a year ago

@TimSchmelter, hmm in that case OP has to iterate first and then modify the field like in your answer. +1

hollyquinn Over a year ago

@TimSchmelter I'm using this data to populate a GridView, it's now saying that other columns in the GridView do not exist. The error message is DataBinding: 'System.String' does not contain a property with the name 'dtmDateCalled'. Do I have to select those in my query? Can you tell me how to fix that? Thank you.

hollyquinn Over a year ago

@Habib your way is working for me, except that my GridView can't find my other columns. Do I have to select all columns in the linq query? Can you tell me how to do that?

Habib Over a year ago

@hollyquinn, I guess your GridView is expecting a List<OCASPhoneCalls>, If that is the case, then use Tim's Answer. Do not change your method return type, Just use the query he has in his answer.

Tim Schmelter · Accepted Answer · 2014-03-07 16:48:31Z

3

You are selecting a List<string> but you are declaring a List<OCASPhoneCalls>, i assume you want to shorten the vcharDiscussion:

List<OCASPhoneCalls> phones = = repo.AllIncluding(p => p.OCASStaff)
    .Where(p =>  p.intNIOSHClaimID == null)
    .ToList();
phones.ForEach(p => p.vcharDiscussion = p.vcharDiscussion.Length > 100 ?
         p.vcharDiscussion.Substring(0, 100) + "..." :
         p.vcharDiscussion);
return phones;

Edit: "I'm getting a null error. vcharDiscussion is coming up null"

Then you need to check that:

phones.ForEach(p => p.vcharDiscussion = 
    p.vcharDiscussion != null && p.vcharDiscussion.Length > 100 ?
    p.vcharDiscussion.Substring(0, 100) + "..." :
    p.vcharDiscussion ?? "");

edited Mar 7, 2014 at 16:48

answered Mar 7, 2014 at 15:36

Tim Schmelter

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8 Comments

hollyquinn Over a year ago

I do want to shorten vcharDiscussion and add ... to the end of it.

Tim Schmelter Over a year ago

@hollyquinn: then this should work. You need to iterate them to modify the property.

hollyquinn Over a year ago

I'm getting the following error message on return phones on this. Cannot implicitly convert type 'System.Collections.Generic.List<CTS.Domain.OCASPhoneCalls>' to 'System.Collections.Generic.List<string>'

Tim Schmelter Over a year ago

@hollyquinn: why have you changed the return type of the method, i thought that you want to return a List<CTS.Domain.OCASPhoneCalls>? I guess you have tested Habib's approach ;-)

hollyquinn Over a year ago

@Time Schmelter you have return phones?? I didn't change it.

|

BRAHIM Kamel · Accepted Answer · 2014-03-07 15:32:40Z

0

`.Select(w => w.vcharDiscussion.Substring(0, 100) + "...")`

because select it's projection and it will return a list of string and your method expect to return

List<OCASPhoneCalls>

answered Mar 7, 2014 at 15:32

BRAHIM Kamel

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