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Null value causing issue saving to the database

I am trying to convert a text box into a decimal when I try this method it says that inpurt string was not in correct format what is the best way around this.
_record.houseHoldArrearsAmount = Convert.ToDecimal(txtArrearsAmount.Text)
I persume it is because text is "" null and and 0.00 hence it falls over
The compiler run time is causing an exception
The input is blank if the user has not entered a value as of yet

If you know that the text is always going to be a number you can still use Convert but check that the string isn't empty first:
if (!string.IsNullOrWhitespace(txtArrearsAmount.Text))
{
_record.houseHoldArrearsAmount = Convert.ToDecimal(txtArrearsAmount.Text);
}
Obviously this won't update the houseHoldArrearsAmount if it's not a numeric value. What you do in this case depends on your business model. You might want to set it to 0 or you might want to leave it with the old value and report and error.
Alternatively, if the input could be any string, you can use Decimal.TryParse to convert the string to a number.
decimal result;
if (decimal.TryParse(txtArrearsAmount.Text, out result))
{
_record.houseHoldArrearsAmount = result;
}

You can use "TryParse" funtion.
decimal householdArrearsAmount = decimal.Zero;
decimal.TryParse(txtArrearsAmount.Text, out householdArrearsAmount);
_record.householdArrearsAmount = householdArrearsAmount;

You can't use the null coalescing operator (as your suggested in comments), as the string value of the textbox won't be null, it will be an empty string.
You could do the following:
_record.householdArrearsAmount =
(string.IsNullOrWhiteSpace(txtArrearsAmount.Text) ? 0 :
Convert.ToDecimal(txtArrearsAmount.Text));

Replace string value with '0' when string is empty

I'm taking a value from a textbox and converting it to decimal. But, the textbox value could be empty. So, how could I handle empty strings from the textbox?
Unfortunately I have around 50 textboxes to deal with, so answers like 'check for null with IF condition' won't help me. My code will look ugly if I use all those IF conditions.
I have this
Convert.ToDecimal(txtSample.Text)
To handle nulls, I did this
Convert.ToDecimal(txtSample.Text = string.IsNullOrEmpty(txtSample.Text) ? "0" : txtSample.Text)
But, the above code is displaying '0' in the textbox. User does not want to see '0'. Another solution is to take text box value into a variable and convert the variable like below.
string variable = txtSample.Text;
Convert.ToDecimal(variable = string.IsNullOrEmpty(variable) ? "0" : variable)
But again, I do not want to define around 50 variables. I am looking for some piece of code that handles null values during conversion without adding the extra line of code.

But, the above code is displaying '0' in the textbox. User does not want to see '0'.
This is because your statement is assigning the new value to txtSample.Text (when you do txtSample.Text = ...). Just remove the assignment:
Convert.ToDecimal(string.IsNullOrEmpty(txtSample.Text) ? "0" : txtSample.Text)
To make things easier if you have many text fields to handle, you can define an extension method :
public static string ZeroIfEmpty(this string s)
{
return string.IsNullOrEmpty(s) ? "0" : s;
}
And use it like this:
Convert.ToDecimal(txtSample.Text.ZeroIfEmpty())

You could make a function to keep from copying the code all over the place.
decimal GetTextboxValue(string textboxText)
{
return Convert.ToDecimal(string.IsNullOrEmpty(textboxText) ? "0" : textboxText);
}
and then use it like this:
GetTextboxValue(txtSample.Text);

You can create an extension method for the string as below
public static decimal ToDecimal(this string strValue)
{
decimal d;
if (decimal.TryParse(strValue, out d))
return d;
return 0;
}
Then you can just txtSample.Text.ToDecimal() in every place.

converting string to datetime in C# on null value exception

I use the below code
extensionRequest[i].EndDate = DateTime.Parse(dsResult.Tables[0].Rows[i]["ActualEndDate"].ToString());
extensionRequest[i].ExtendedEndDate = DateTime.Parse(dsResult.Tables[0].Rows[i]["ExtendedEndDate"].ToString());
extensionRequest[i].ReceivedDate =Convert.ToDateTime(dsResult.Tables[0].Rows[i]["dReceivedOn"].ToString());
this works fine when values are coming from the DB
but when NULL values are returned it throws an exception!!
Should i check values for all three values like the code below
if (dsResult.Tables[0].Rows[i]["dReceivedOn"].ToString()==null){
extensionRequest[i].ReceivedDate="";
}
else{
extensionRequest[i].ReceivedDate =Convert.ToDateTime(dsResult.Tables[0].Rows[i]["dReceivedOn"].ToString());
}
or i should assign all dates to null on exception?!
is there any other way to do in single line? like tryparse or something?

I'll try being creative. You can create a Nullable TryParse as an Extension Method edition:
public static DateTime? TryParseNullable(this DateTime dateTime, string val)
{
DateTime outValue;
return DateTime.TryParse(val, out outValue) ? (DateTime?) outValue : null;
}
and then use:
extensionRequest[i].EndDate = DateTime.TryParseNullable(dsResult.Tables[0].Rows[i]["ActualEndDate"].ToString());
and that can be your one liner.

You can use DateTime.TryParse() method which returns true on successfull conversion otherwise returns false.
Note: calling ToString() on null throw NullReferenceException hence you need to check for null value before conversion.
Try This:
if(dsResult.Tables[0].Rows[i]["ActualEndDate"] != null)
DateTime.TryParse(dsResult.Tables[0].Rows[i]["ActualEndDate"].ToString(),
out extensionRequest[i].EndDate);

You can check if value is null like this
extensionRequest[i].EndDate = Convert.IsDbNull(dsResult.Tables[0].Rows[i]["ActualEndDate"]) ? null : Convert.ToDateTime(dsResult.Tables[0].Rows[i]["ActualEndDate"]);
I'm sure .ToString() is not required.
It will be more readable if you cache a row to the local variable:
var row = dsResult.Tables[0].Rows[i];
...
extensionRequest[i].EndDate = Convert.IsDbNull(row["ActualEndDate"]) ? null : Convert.ToDateTime(row["ActualEndDate"]);
Be sure .EndDate and others allow null values. In other words, that is DateTime?

asp.net master property string, how to check in content page if string is empty

if i have a master property string for example:
public String SharedInfo
{
get { return (String)Session["SharedInfo"]; }
set { Session["SharedInfo"] = value; }
}
and a label in an content page, i check if the string is empty by doing:
if(Master.SharedInfo == null)
now my question is: why does if(Master.SharedInfo == "") not work, because the SharedInfo is a string right?

There is a handy method that "catches" both
if (String.IsNullOrEmpty(Master.SharedInfo)) {
...
}
null and "" are not equal. null means no string at all. "" is a string of length 0.
string s = null;
int i = s.Length; // <-- Throws null reference exception
But
string s = "";
int i = s.Length; // OK, i => 0
"" and String.Empty are equivalent. Some people state that you should always use String.Empty instead of "", but it makes really no difference.
UPDATE
Equal string constants are interned by the compiler, i.e. the compiler stores equal constants only once. You can make a simple test (in response to #BobTodd's comment),
string s = "";
Console.WriteLine(Object.ReferenceEquals(s, "")); // --> true
Console.WriteLine(Object.ReferenceEquals(s, String.Empty)); // --> true
For the sake of completeness (according to #JoelEtherton's comment). Starting from .NET Framework 4.0 you can test
if (String.IsNullOrWhitespace(Master.SharedInfo)) {
...
}
This will catch strings like " " or "\t" as well.

In c#, an empty string "" is not null. It's an actual string, with length equals to zero.
You can use string.IsNullOrEmpty(string stringToTest) to check both null and empty strings.

String.Empty ("") and null are quite different
It depends wholly on what has been written to Session["SharedInfo"].
If nothing has, then it will be null, otherwise its the value written, which could be an empty string or null.
To be sure use String.IsNullOrEmpty(string #string)

Getting "" value of Location in Lotus Notes Calendar

I am trying to read Location of Calendar item in Lotus Notes.
When i check in Document Properties manually.I am able to view the value,
But when i read it via using Domino.dll in am getting "" value.
I am using:
String Location = ((object[])CalendarDoc.GetItemValue("Location"))[0] as String;
Also tried :
String tmpLocation = ((object[])CalendarDoc.GetItemValue("tmpLocation"))[0] as String;
is there any other way to get 'Location' value ? using Domino.dll in C#.
Thanx

Here's a wild guess... I'm wondering if it's the as string that's causing your issues. I think it depends on the object type being returned by GetItemValue. I'm guessing at runtime it will try to cast your object to a string which might not be what you want. You might just want the text that the object represents (assuming that the ToString gives that).
string location = GetLocationFromDocument();
private string GetLocationFromDocument()
{
object[] values = CalendarDoc.GetItemValue("Location");
if( values != null && values.Length > 0 && values[0] != null )
{
return values[0].ToString();
}
return string.Empty;
}
Sorry, I don't have the required assemblies to test this. If this doesn't work I can delete my answer because I don't wan't bad information floating around.