# Getting column values from a datatable

Is there a way I can make the code compact and with fewer ifs?

theData = GetData();
if (theData.Rows.Count > 0)
{
MyModel = new CustomModel();
dataSetRow = theData.Rows[0];
if (theData.Columns.Contains("Column1"))
{
if ((!object.ReferenceEquals(dataSetRow["Column1"], DBNull.Value)))
{
MyModel.Column1 = Convert.ToString(dataSetRow["Column1"]);
}
}
if (theData.Columns.Contains("Column2"))
{
if ((!object.ReferenceEquals(dataSetRow["Column2"], DBNull.Value)))
{
MyModel.Column2 = Convert.ToString(dataSetRow["Column2"]);
}
}
if (theData.Columns.Contains("Column3"))
{
if ((!object.ReferenceEquals(dataSetRow["Column3"], DBNull.Value)))
{
MyModel.Column3 = Convert.ToString(dataSetRow["Column3"]);
}
}
if (theData.Columns.Contains("Column4"))
{
if ((!object.ReferenceEquals(dataSetRow["Column4"], DBNull.Value)))
{
MyModel.Column4 = Convert.ToString(dataSetRow["Column4"]);
}
}

• I see 4 very similar blocks. Reduce them to one by using a loop over the constants "Column1", "Column2", "Column3", "Column4" – MrSmith42 Jan 28 '15 at 12:15
• Is this real code ? – Heslacher Jan 28 '15 at 12:33
• @MrSmith42 MyModel.Column3 would not be replacable by MyModel["Column3"] or something similar as it is a property of a class. – Abbas Jan 28 '15 at 12:45
• @Abbas You are right but you can still use a loop and use the loop index to select 'MyModel.Column1' to 'MyModel.Column4' which you stored in an array. – MrSmith42 Jan 28 '15 at 15:27
• How are you going to select the property with an indexer without using reflection? – Abbas Jan 28 '15 at 15:33

Useful property names:

I find using names as theData bad practice. It doesn't give any info on the instance. Give it a useful name you, and others, easily understand.

Casing of property names:

Don't use PascalCase for local fields, use camelCase instead. Your MyModel will become myModel. You had already done this correctly for dataSetRow.

Redundant parentheses:

Following:

if ((!object.ReferenceEquals(dataSetRow["Column1"], DBNull.Value)))


can be replaced by:

if (!object.ReferenceEquals(dataSetRow["Column1"], DBNull.Value))


There's no need to encapsulate the whole expression again in parantheses.

Simplifying the code:

Finally, the important part! :) There's only one way I can think of to achieve this: reflection. I created following extension method to get the PropertyInfo of your instance (note that it doesn't have to be placed in an extension method, I only think it looks cleaner and is good for reusability elsewhere if needed):

public static class Extensions
{
public static PropertyInfo GetProperty<T>(this T obj, string propertyName) where T : class
{
return typeof(T).GetProperty(propertyName);
}
}


The above allows you to do following (get a property by it's name-value):

public class User
{
public int ID { get; set; }
public string Name { get; set; }
}

var user = new User { ID = 1, Name = "Simsons" };
var nameProp = user.GetProperty("Name");


And now you can get and/or set the value of that property using the GetValue() or SetValue() methods:

nameProp.SetValue(user, "Abbas", null);


• place all your column names in an array over which you will loop
• simplify your code using the reflection part

Here's your code with the above applied:

theData = GetData();

if (theData.Rows.Count > 0)
{
myModel = new CustomModel();
dataSetRow = theData.Rows[0];
var columnNames = new [] { "Column1", "Column2", "Column3", "Column4" };

foreach(var columName in columnNames)
{
if(theData.Columns.Contains(columName))
{
if (!object.ReferenceEquals(dataSetRow[columName], DBNull.Value))
{
var columnProperty = myModel.GetProperty(columName);
columnProperty.SetValue(myModel, Convert.ToString(dataSetRow[columnName], null);
}
}
}
}


Update:

As RobH stated in the comments, you can use LinQ to avoid nested if statements. Here's how your code would look like:

var columnNames = new [] { "Column1", "Column2", "Column3", "Column4" };

foreach(var existingColumn in columnNames.Where(x => theData.Columns.Contains(x)))
{
if (!object.ReferenceEquals(dataSetRow[existingColumn], DBNull.Value))
{
var columnProperty = myModel.GetProperty(existingColumn);
columnProperty.SetValue(myModel, Convert.ToString(dataSetRow[existingColumn], null);
}
}


You can even take it a final step further to avoid any if statement:

var validColumns = columnNames.Where(x => theData.Columns.Contains(x) &&
!object.ReferenceEquals(dataSetRow[x], DBNull.Value)))

foreach(var column in validColumns)
{
var columnProperty = myModel.GetProperty(existingColumn);
columnProperty.SetValue(myModel, Convert.ToString(dataSetRow[existingColumn], null);
}

• +1. You could convert most of that foreach to LINQ though, might look a bit nicer than the nested ifs. – RobH Jan 28 '15 at 14:34
• @RobH Thanks for the tip, updated my answer. ;) – Abbas Jan 28 '15 at 15:32

If you can refactor your model class so that the column names and values are in a dictionary instead of separate properties everything an be simplified to one LINQ statement:

class CustomModel
{
public Dictionary<string, string> ColumnValues = new Dictionary<string, string>
{
{ "Column1", "" },
{ "Column2", "" },
{ "Column3", "" },
{ "Column4", "" }
};
}

var dataSetRow = theData.Rows[0];
CustomModel MyModel = new CustomModel();
MyModel.ColumnValues = (from DataColumn c in theData.Columns
where MyModel.ColumnValues.ContainsKey(c.ColumnName) && dataSetRow[c] != DBNull.Value
select new KeyValuePair<string, string>(c.ColumnName, dataSetRow[c].ToString())).ToDictionary(x => x.Key, x => x.Value);