c#

if Approved is a boolean, then it cannot be null. If it is a Nullable class, then it can be null, but needs a bit tweaking:

ddlApprovalStatus.SelectedValue =
!details.Approved.HasValue ? "Pending" :
(details.Approved == true ? "Approved" : "Denied");

In conjunction with what abel said, to define as nullable:

Nullable<bool> ddlApprovalStatus;

-or-

bool? ddlApprovalStatus;

@kaufmed: you probably mean the Approved field/property in the Details class?

private bool? _bool = null;public bool? Approved{ get { return _bool; }}

I probably screwed it up : P...

in any event, the name is arbitrary, the syntax is the main idea :)

ASKER

@abel

Approved field is actually a boolean....

details class has this :
private bool? _bool = null;
public bool? Approved
{
get
{
return _bool;
}
}

In the data layer where I am reading this field value from database do I need to add any line of code....below is the line in the datalayer....
datadetails.Approved = Convert.ToBoolean(reader["Approved"]);

now it is throwing an error.....
Object cannot be cast from DBNull to other types.

I appreciate if you can tell me a solution...

null and DBNull are not the same things. So you have to check for DBNull when reading from a reader:

datadetails.Approved = reader.IsDbNull(columnIndex_of_Approved_in_reader) ? null : Convert.ToBoolean(reader["Approved"]);

yeah, that's on the other end of the line... try this

if (DbNull.Value.Equals(reader["Approved"]) {
datadetails.Approved = null;
} else {
datadetails.Approved = Convert.ToBoolean(reader["Approved"]);
}

parenthesis missing, sorry (didn't test it):

if (DbNull.Value.Equals(reader["Approved"])) {
datadetails.Approved = null;
} else {
datadetails.Approved = Convert.ToBoolean(reader["Approved"]);
}

(i like kaufmeds solution better: more concise)

I don't know though, I don't like switching between column index and column name when working with readers (seems cluttered to me), so I might be inclined to incorporate you suggestion. (I've haven't really used the DBNull.Value approach before).

I never use the reader at all, anyway, lol. Whenever I do DB, I let it be done by the ORM so that I don't have to worry about these little things. It takes more time to setup, but it gives you more value in the end. Personally, I like NHibernate for that task.

ASKER

If I use kaufmed solution of : datadetails.Approved = reader.IsDbNull(columnIndex_of_Approved_in_reader) ? null : Convert.ToBoolean(reader["Approved"]);

Type of conditional expression cannot be determined because there is no implicit conversion between '<null>' and 'bool'

it is throwing an error...

But when I use abel's code as the code snippet attached it is not displaying the selected value in the drop down list....

in the ddlapprovalstatus.selectedvalue it is reading blank""...what should I do????

datalayer.cs:(here it is going through and reading through the clause correctly) 
   if (DBNull.Value.Equals(reader["Approved"]))
                            {
                                datadetails.Approved = null;
                            }
                            else
                            {
                                datadetails.Approved = Convert.ToBoolean(reader["Approved"]);
                            }
                            
 
Businessobjects:
 private bool? _approved=null;
    public bool? Approved
        {
            get { return _approved; }
            set { _approved = value; }
        }
 
.aspx.cs:
 
            ddlApprovalStatus.SelectedValue = !details.Approved.HasValue ? "Pending" :(details.Approved == true ? "Approved" : "Denied");

Open in new window

> there is no implicit conversion between '<null>' and 'bool'

that probably means the receiving boolean is not nullable. Or there's another error. You can split the statement in an if-statement (which is always a good idea if the "?:" ternary operator is not well readable).

> it is not displaying the selected value in the drop down list....
> in the ddlapprovalstatus.selectedvalue it is reading blank""...what should I do????

take a beer and some sunshine ;)

No, seriously. What you should do is check what's currently in the dropdownlist. Can it be that the dropdownlist does not contain a selectedvalue of type Pending|Approved|Denied? You can list the items by:

foreach (ListItem item in ddlApprovalStatus.Items)
Debug.WriteLine(item.value);

which should show all the options that are currently loaded in the output window.

-- Abel --

ASKER

dropdownlist does not contain a selectedvalue of type Pending|Approved|Denied?

Yeah the drop down list has another value.....these are all hard coded Not set|pending|Approved|Denied...the not set may not come in any criteria that happens when there is no record in that particular table........

ASKER CERTIFIED SOLUTION

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ASKER

Hmm....that's correct.....I didn't copy paste but I was typing..it's a typo mistake....I appreciate your help:)

Glad you found it. You know, it is often better to use the Index property instead of the Value property, because the index is less error prone to typo's... :)

glad it helped

-- Abel --

ASKER

abel

I have a similar simple question ....I appreciate if you can help me that.....posting a different question doesn't help at all......

I have a string which reads the data from the database correctly but it displays blank in the

ddlFileType.selectedvalue.....can you help me with this???

ddlFileType.SelectedValue = details.FileType.ToString();