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.
Related
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));
In C# 6.0, string interpolations are added.
string myString = $"Value is {someValue}";
How are null values handled in the above example? (if someValue is null)
EDIT:
Just to clarify, I have tested and am aware that it didn't fail, the question was opened to identify whether there are any cases to be aware of, where I'd have to check for nulls before using string interpolation.
That's just the same as string.Format("Value is {0}", someValue) which will check for a null reference and replace it with an empty string. It will however throw an exception if you actually pass null like this string.Format("Value is {0}", null). However in the case of $"Value is {null}" that null is set to an argument first and will not throw.
From TryRoslyn, it's decompiled as;
string arg = null;
string.Format("Value is {0}", arg);
and String.Format will use empty string for null values. In The Format method in brief section;
If the value of the argument is null, the format item is replaced with
String.Empty.
It seems that the behavior depends on which underlying formatting methods are called, and the implementation of these can change over time. If you get a null formated into the string such as "(null)", it is not sure this will stay the same over several years. In some newer version of .NET it can start throwing an exception.
So I think the most safe approach is to make some condition to avoid using the null. Write a simple ternary operation like:
int? someValue = 5;
var valueStr = (someValue is not null) ? someValue.ToString() : string.Empty;
var myString = $"Value is {valueStr}";
It is an extra line of code, but at least the behavior is controlled.
In my table of MySQL Db I have the field Check.
The value memorized on the field Check it could be : null or -1.
When the value memorized on the field Check is null or -1 I need in return the xxx value. and I have tried :
string Check = sdr["Check"] == DBNull.Value || sdr["Check"] == "-1,00" ? "xxx" : sdr["Check"].ToString();
Without success because the output is always -1,00.
How to do resolve this?
Please help me, thank you so much in advance.
The problem is that you are comparing the wrong objects. The values returned from System.Data result sets are wrappers around the actual value. What you want are the typed versions. Basically, the check should look like this:
int checkIndex = sdr.GetOrdinal("Check");
string Check = sdr.IsDBNull(checkIndex) || (sdr.GetString(checkIndex) == "-1,00") ? "xxx" : sdr.GetString(checkIndex);
If you "Check" is actually a number, you may want to use the IntValue("Check") call, just to deal with globalization issues if your app is ever deployed where they use a "." instead of a "," for your decimal point.
See https://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqldatareader(v=vs.110).aspx for the full API.
If your MySQL database is not set to use the same locale formatting as your C# application, your assumptions about number formats could be incorrect. To make a more robust version of your check, I would recommend something like this:
int checkIndex = sdr.GetOrdinal("Check");
string Check = "xxx";
double checkValue = sdr.IsDBNull(checkIndex) ? -1 : Convert.ToDouble(sdr[checkIndex]);
if (checkValue != -1)
{
Check = checkValue.ToString(CultureInfo.CurrentCulture);
}
If the data type is decimal 10,2 you need Convert.ToDecimal the value :
string Check = (sdr["Check"] == DBNull.Value || Convert.ToDecimal(sdr["Check"]) == -1) ? "xxx" : sdr["Check"].ToString();
You can compare a string empty or null by below code
string str = Your string
if(String.IsNullOrEmpty(str))
{
if yes, it comes here
}
else
{
if not, it comes here
}
The String.IsNullOrEmpty() is a bool type.
I am having trouble converting a value in a string array to int since the value could possibly be null.
StreamReader reader = File.OpenText(filePath);
string currentLine = reader.ReadLine();
string[] splitLine = currentLine.Split(new char[] { '|' });
object.intValue = Convert.ToInt32(splitLine[10]);
This works great except for when splitLine[10] is null.
An error is thrown: `System.FormatException: Input string was not in a correct format.
Can someone provide me with some advice as to what the best approach in handling this would be?
Don't use convert, it is better to use
int.TryParse()
e.g.
int val = 0;
if (int.TryParse(splitLine[10], out val))
obj.intValue = val;
You can use a TryParse method:
int value;
if(Int32.TryParse(splitLine[10], out value))
{
object.intValue = value;
}
else
{
// Do something with incorrect parse value
}
if (splitLine[10] != null)
object.intValue = Convert.ToInt32(splitLine[10]);
else
//do something else, if you want
You might also want to check that splitLine.Length > 10 before getting splitLine[10].
If you're reading something like a CSV file, and there's a chance it could be somewhat complicated, such as reading multiple values, it probably will make sense for you to use a connection string or other library-sorta-thing to read your file. Get example connection strings from http://www.connectionstrings.com/textfile, using Delimited(|) to specify your delimiter, and then use them like using (var conn = new OleDbConnection(connectionString)). See the section in http://www.codeproject.com/Articles/27802/Using-OleDb-to-Import-Text-Files-tab-CSV-custom about using the Jet engine.
I would go with
object.intValue = int.Parse(splitLine[10] ?? "<int value you want>");
if you're looking for the least code to write, try
object.intValue = Convert.ToInt32(splitLine[10] ?? "0");
If you want to preserve the meaning of the null in splitLine[10], then you will need to change the type of intValue to be of type Nullable<Int32>, and then you can assign null to it. That's going to represent a lot more work, but that is the best way to use null values with value types like integers, regardless of how you get them.
I'm saving a numeric value into a datatable cell (no datatype for the cell has been explicitly declared), then later retrieving that data and trying to format it into a string. Problem is that nothing I've tried will properly format the string.
50000 --> 50,000
I've tried (where r is the row in a loop):
String.Format("{0:0,0}", r["columnName"])
r["columnName"].ToString("n0")
And several variations without any luck. Most of the time I just get the number without the comma.
String.Format("{0:0,0}",int.Parse(r["columnName"].ToString()))
Probably not the most elegant solution, but you could just iterate backwards from the tail-end of the string (or from the decimal point) adding a comma every three characters until you run out.
It might be helpful to have more context for what you're trying to do, but here is an example of getting a value out of a DataTable and then formatting it as desired.
DataTable dt = new DataTable();
dt.Columns.Add( "cellName", typeof( double ) );
dt.Rows.Add( 123.45 );
string val = ( (double)dt.Rows[0]["cellName"] ).ToString( "N" ); // val = "123.45"
I'm explicitly casting the value back to a double before calling ToString. You could also call string.Format on that value instead of ToString and it should work just as well.
EDIT: If you're storing the value as a string and then want to format it, use this:
string val = ( double.Parse( dt.Rows[0]["cellName"] ) ).ToString( "N" );
This does assume that the value is parsable though (i.e. isn't null).
The problem with these methods is that depending on the structure of the underlying table that field may be null. If you try to cast a null value held as an object (in the DataTable) to string,integer, decimal, or what have you... your app will blow up 100% of the time. Unless your DataSet is a strongly typed data set you will always want to do this error checking. As a matter of fact, writing a small data reading class to read string, decimals, date times, integers, whatever... is a must in any Data access operations having to do with Database....
So here is more error proof approach which idealy should be wrapped in a helper method as shown here:
public static string GetFormatedDecimalString(DataRow row, string columnName, string format)
{
string ColumnNameStringValue = String.Empty;
decimal ColumnNameValue = Decimal.Zero;
if( row[columnName) == DBNull.Value )
{
ColumnNameValue = Decimal.Zero;
}
else
{
ColumnNameStringValue = row[columnName].ToString();
if( ! Decimal.TryParse(ColumnNameStringValue, out ColumnNameValue )
{
ColumnNameValue = Decimal.Zero;
}
// if the if statement evaluated to false the ColumnNameValue will have the right
// number you are looking for.
}
return ColumnNameValue.ToString(format);
}
passing "N" or "{0:0,0}" as the format string will work just fine.