Category: App Services

All about application services for example, Azure App Service. Angular application, Microsoft .NET Core and EF

Dataset and Data Tables (a refresher)

Dataset is an in-memory representation of a database relationship. Data Tables are individual tables that can be joined with Data relation objects.

Let’s go through an example of a tenant and his/her maintenance request;

Create a Dataset;

//create dataset
DataSet serviceRequest = new DataSet();

Create tenant table

//create tenant table
DataTable tenant = new DataTable();
tenant.Clear();
//add columns
tenant.TableName = "tenant";
tenant.Columns.Add("tenantID");
tenant.Columns.Add("Name");
tenant.Columns.Add("AptNumber");
//add rows
DataRow rowT = tenant.NewRow();
rowT["tenantID"] = "A1";
rowT["Name"] = "khan";
rowT["AptNumber"] = "1";
tenant.Rows.Add(rowT);

//Add this table to data set
serviceRequest.Tables.Add(tenant);

Create request table

//create request table
DataTable request = new DataTable();
request.Clear();
//add columns
request.TableName = "request";
request.Columns.Add("requestID");
request.Columns.Add("tenantID");
request.Columns.Add("description");
//add rows
DataRow rowR = request.NewRow();
rowR["requestID"] = "1";
rowR["tenantID"] = "A1";
rowR["description"] = "air conditioner does not work";
request.Rows.Add(rowR);
//add this table to data set
serviceRequest.Tables.Add(request);

Create relationship

//create relationship
DataRelation relation;
DataColumn tenantColumn = serviceRequest.Tables["tenant"].Columns["tenantID"];
DataColumn requestColumn = serviceRequest.Tables["request"].Columns["tenantID"];
relation = new DataRelation("relation", tenantColumn, requestColumn);
//assign relation
serviceRequest.Relations.Add(relation);

Create LINQ query to read data;

//simple LINQ query
var maintenanceData = (from x in serviceRequest.Tables["tenant"].AsEnumerable()
join y in serviceRequest.Tables["request"].AsEnumerable()
on x.Field<string>("tenantID") equals y.Field<string>("tenantID")
select new
   {
       TenantID = x.Field<string>("tenantID"),
       RequestID = y.Field<string>("requestID"),
       Description = y.Field<string>("description")
   }).ToList();

Here is the output of this LINQ query;

If we are going to add a new column in request table, for example AllowToEnterApt. We can use foreach loop to update the values in this column;

serviceRequest.Tables["request"].Columns.Add("AllowToEnterApt");
foreach (DataRow row in serviceRequest.Tables["request"].Rows)
{
     row["AllowToEnterApt"] = 1;
}

Remove single quote from strings

I would like to remove single quote from beginning and end of this string;

string tabName = "'i# milestones$'";
string outputTabName = tabName.Trim(new char[]{(char)39});

Where (char)39 represents ', and the .Trim() will remove the first and last ' from the string; You can try like this as well:

string outputTabName = tabName.Trim('\'');

Throw exceptions in SQL and C#

This is how we can throw an exception in C#;

static void CopyObject(SampleClass original)
{
    if (original == null)
    {
        throw new System.ArgumentException("Parameter cannot be null", "original");
    }
}

This is how we can throw an exception in SQL;

BEGIN TRY
	SET NOCOUNT ON;

	SELECT 1/0;

END TRY  
BEGIN CATCH  
    --SELECT   
    --    ERROR_NUMBER() AS ErrorNumber  
    --    ,ERROR_SEVERITY() AS ErrorSeverity  
    --    ,ERROR_STATE() AS ErrorState  
    --    ,ERROR_PROCEDURE() AS ErrorProcedure  
    --    ,ERROR_LINE() AS ErrorLine  
    --    ,ERROR_MESSAGE() AS ErrorMessage;  
    THROW;
END CATCH;

If you don’t want to throw exception, comment “THROW” keyword. This will stop propagating exception to calling method and “catch(SqlException ex)” block will never be able to see it.

Uncomment all other lines. You have to use data reader to get result back and handle exception manually.

Visual Studio Debugger Failed to launch debug adapter

All of sudden I started getting this error;

If I change launchBrowser to false in launchSetting.json file,  I can successfully start the project, and then open the browser and navigate to the url manually.

launchBrowser: false

If I run project “without debugging” by pressing CTRL+F5, it runs fine but I loose debugging feature.

The quick fix is to never use JavaScript debugging in Visual Studio. The Chrome JavaScript debugger is a much better alternative for debugging.

To turn off debugging and fix the problem follow this;

You can confirm this change;

The pain is gone.

Resourceshttps://stackoverflow.com/questions/58767169/visual-studio-2017-failed-to-launch-debug-adapter-chrome