[dba-VB] C# serialization

Hi John

Oh, I don't regard myself as a master in C# and you will probably learn something that is new to me. However, coming from Access, I went straight ahead for the database (dataset) stuff as I can see people are wasting endless hours writing primitive SqlCommand code as if nothing has happened since classic ASP or VB4.

For very simple applications you may not need much more than your current task: write your values to an ini .. sorry xml file and read it back at the next launch. For this, no database engine is needed, not even Access/JET, but XML files fit nicely this purpose (and more).

/gustav


>>> jwcolby at colbyconsulting.com 13-10-2009 18:13 >>>
 > Of course, I can see an educational purpose by handcrafting a kind of database, but ...

LOL.  Well, this is after a CLASS in C# the purpose of which is to LEARN C#.  You do not start at 
typed data sets, you start with "this is a variable" and "this is a for loop".  I am very much at 
that level.

I am quite sure that in a year I will be throwing out typed datasets with the best of them but right 
now I am still forgetting to put a ; at the end of the line.

Have patience Master #2.

John W. Colby
www.ColbyConsulting.com 


Gustav Brock wrote:
> Hi John
> 
> Sounds like a quite normal database app to me ...
> 
> If so, all the typed dataset stuff is ready at your hands.
> To persist (to an XML file without the overhead you claim about) use method WriteXml.
> To read it at load, use method ReadXml. Can't be simpler.
> 
> Of course, I can see an educational purpose by handcrafting a kind of database, but ...
> 
> /gustav
> 
> 
>>>> jwcolby at colbyconsulting.com 13-10-2009 17:37 >>>
>  >Do these classes inherit typed datasets?
> 
> Nope, no connection to a database.
> 
> The original assignment was to build a grade calculator where you simply input a list of grades. 
> There are three types of grades, each with a different weight (Tests - 40% of grade, Labs - 50% of 
> grade and DL 10% of grade).
> 
> There is no requirement to do anything more than the above, calculating a total count of each grade 
> type, sum of each type, average of each type and weighted average of each type, and then the same 
> calculations for the totals.
> 
> In order not to be bored to death, and with the approval of the instructor, I expanded the 
> assignment to include using classes and collections.  I store each grade in an instance of clsGrade. 
>   I store all of each TYPE of grade in an instance of clsGrades (plural) which contains a generic 
> collection into which the instances of clsGrade are inserted.  This collection is strongly typed so 
> that it can only accept clsGrade objects.
> 
> Each instance of clsGrades (plural) is inserted into a sorted list in clsCalculator, keyed on 
> GradeType (keyed on the string "Test", "Lab" or "DL").  In the main form there is a combo with three 
> grade type strings ("Test", "Lab" and "DL") which when selected is passed in to clsCalculator which 
> indexes into the collection to access the correct instance of clsGrades.  Adding new grades, 
> deleting grades and updating existing grades is all done on the selected instance of clsGrades.
> 
> So...
> 
> clsCalculator - interfaces to the form and has a sorted collection holding three instances of...
> clsGrades - contains a strongly typed generic collection holding multiple instances of ...
> clsGrade - contains each grade.
> 
> clsGrades performs the calculations to count (collection.count), sum, average and weighted average 
> all of the grades contained within.
> 
> clsCalculator requests the various computed values from the three instances of clsGrades and 
> performs the calculations to create an overall Count (sum of clsGrades.Count), Sum (sum of 
> clsGrades.Sum), Average, weighted sum etc.
> 
> Now...
> 
> I want to write the grades in each clsGrades instance to a single file, then read it back in again. 
>   Persist the grades to disk.  I have no requirement to persist the data to disk, I simply want to 
> do so.
> 
> Please please please do not suggest a "better way" for doing the assignment, it is all written and 
> functions exactly as you would expect it to work.  You may of course enlighten me on different 
> options, but I will not be rewriting the core assignment at this point.
> 
> This was just a homework assignment and it is in fact finished.  If I can persist it great, if not 
> that's OK too.  I have learned a lot and thought I might learn how to do the persist thing, streams, 
> serialization (if that is used) etc.  Even classes and collections are a "next semester" thing so I 
> am ahead of the curve at this point.
> 
> John W. Colby
> www.ColbyConsulting.com 
> 
> 
> Charlotte Foust wrote:
>> John,
>>
>> I'm not sure I understand what you're doing.  Do these classes inherit
>> typed datasets?  If so, the parent class can easily return a child class
>> that already contains a typed dataset of child records.  You don't
>> actually need collections for that.  In that case, grade wouldn't need
>> to be a class (although it could be, I just don't see any need).  The 
>>
>> Charlotte Foust