PvWay.MultiPartVarChar.nc8 1.0.0

MultiPart VarChar for .Net Core 8

Persists (and retrieves) multi part text values IDictionary<string, string> into (and from) a single VARCHAR column into a database.

Usage

Constructor

From the business layer of your application use the Dictionary constructor

	
	var dic = new Dictionary<string, string>()
	{
		{"en", "bear"},
		{"fr", "ours"}
	};
	IPvWayMpVarChar myMpVarChar = new PvWayMpVarChar(dic);

Persisting into the Db

Now let's persist this value in one single NVARCHAR() column into the Db.

The following example prepares a simple SQL statement for a DAO implementation of the DAL but of course you may want to use this with the ORM of your choice (EF, NHibernate...)

	
    // convert myMpVarChar to a string for insertion into the Db.
    var mpText = myMpVarChar.ToString();
    
    // hum yes... in this case we should make sure we escape the single quotes if any
    mpText = mpText.Replace("'", "''");

    // now we can use this var into an insert statement
    var insertStatement = $"INSERT INTO [dbo].[MyTable] ([MpText]) VALUES ('{mpText}');";
    
    // The line above will generate the following text
    // INSERT INTO [dbo].[MyTable] ([MpText]) VALUES ('<en>bear</en><fr>ours</fr>');

    // for the simplicity I do not provide here the code executing this insert

The key value dictionary is serialized to a single string that can be saved into the db into a VARCHAR(xxx) (or NVARCHAR(xxx)) column.

Up to you to see if you need a MAX length or if a smaller column will do the job.

It takes the using XML tags '<key>value</key>.

Example: <en>Bear</en><fr>Ours</fr>

Retrieving the data from the Db

  // (not shown) here above the SELECT code that populates the reader object 
  var ord = reader.GetOrdinal("MpText");
  
  // let's retreive the raw text from the Db
  var retrievedMpText = reader.GetString(ord); 

  // time to deserialize
  // for this we will use the static method TryDeserialize 
  var deserializeResult = PvWayMpVarChar.TryDeserialize(
  	retrievedMpText, 
  	out var retrievedMpVarChar, 
  	out var errorMessageIfAny);

  if (!deserializeResult == PvWayDeserializationResult.Failed)
  {
  	Console.WriteLine("it failed");
  	Console.WriteLine(errorMessageIfAny);
  	// log and throw
  }
  else
  {
    // Deserialization succeeded
    
  	// three ways to get the data
  	
    // (1) using the Dicionnary
    var enVal = retrievedMpVarChar.MpDic["en"];
    Console.WriteLine(enVal);
	// ==> displays "bear"... or throws an error if there is no entry for "en"
    
    // using the GetPartForKey method
    var frVal = retrievedMpVarChar.GetPartForKey("fr");
    Console.WriteLine(frVal);
	// ==> displays "ours"... or null if there is not entry for "fr"             
    
    // using the FindPartForKey method
    var findResult = retrievedMpVarChar.FindPartForKey("de", out var deVal);
    Console.WriteLine(deVal);
	// ==> displays "bear" taking de first key in the dic as default value
	// the findResult equals PvWayFindPartResult.FirstValue              
  }

Thanks for reading so far 😃