LINQ to SQL grouping and passing onto a view - asp.net

I am new to Asp.Net, MVC3, Linq, and everything else related to it. I'm very used to PHP and ColdFusion so pardon my ignorance! Essentially what I am trying to do is re-create the situation in ColdFusion where I can perform the equivalent of a cfoutput's group attribute. I'm so used to just calling a stored procedure and then doing
<cfoutput group="id">
and then another inner cfoutput for any columns that have non-distinct data. Works like a charm! Not so much in Asp.Net.
I would like to stay with using my stored procedure, which is returning a join from two tables with a one-to-many relationship. For example's sake let's say I have 3 columns: a full name, a title, and a graduation year. The graduation year is the column from the joined table, so my result from the stored procedure looks like this:
Jim Professor 2005
Jim Professor 2008
Jim Professor 2011
I am sending this to the View. I am assuming it's the View's job to then group the data based on one of the columns (probably the full name). I want to output an HTML table with 3 columns and in this situation I would have ONE row:
Jim Professor 2005, 2008, 2011
I have googled tons of examples that use this thing called a group key. This does not seem to help me because I'm not interested in just outputting one value "Jim" (or whatever the grouped value is), I need both "Jim" and "Professor" values to be output for each row. My thinking is I would need 2 foreach loops, the outer loop displaying the fullname and title and the inner loop going through all possible matches for the graduation years. I cannot seem to get the graduation years in a group, especially with this IGrouping syntax. The key can only store one value and I need every value on that row, I only really need one or two values to be iterated over. Should I try and create a custom view model after I perform a secondary linq grouping and then send that to a strongly typed view?
EDIT:
Ok, I have code that works but it seems very inefficient as I basically have to re-define all of the columns/values that I have from my stored procedure. It almost makes me want to forget stored procedures and just use LINQ for everything. It seems what I was asking for is a kind of "group on multiple columns" and link helped immensely.
var records = db.getRecords();
var groups = from r in records
group r by new
{
r.id
}
into row
select new ListVM()
{
id = row.Key.id,
fullname = row.Select(x => x.fullname).First(),
title = row.Select(x => x.title).First(),
degrees = row.Select(x => x.degree_name).ToList(),
majors = row.Select(x => x.major_name).ToList()
};
return View(groups);
I of course had to create a ViewModel for this to work. In my view then I can use for loops to iterate over the degrees and majors lists. Is this the best way to do this? I just generally need more than just the group key to display my entire row of information, and only want to iterate over lists once or twice in a 20 column row, as opposed to only displaying the group key once and iterating over everything in most examples I see.

I'm not that big specialist with Linq and MVC, but faced with your problem I would:
Deal with data preparation in controller/model, after being taught that view should be concerned with displaying things only.
I would use knowledge from these topics to solve your particular problem:
a) grouping by multiple columns:
Group By Multiple Columns
b) Concatenation as an aggregate function:
Using LINQ to concatenate strings
c) Using aggregates and grouping by multiple columns
How to write a LINQ query combining group by and aggregates?
Once you have data in your view model, just display it.

I believe I've finally found out how to solve what I was looking for. A "group join" seems to solve my problem with ease. The information I found on this page solved it: http://geekswithblogs.net/WillSmith/archive/2008/05/28/linq-joins-and-groupings.aspx

Related

SQLite sort for varchar alphanumeric list

I'm writing a music program with SQLite as a back-end and I'm trying to work out how to sort all the albums in the order I want them. In theory, this is pretty easy but there's just the odd one I'm having trouble with as below.
Take these three albums - how to I get them sorted in this order when using SELECT DISTINCT Album FROM Album ORDER BY Album COLLATE NOCASE:
Now That's What I Call Music! 10
Now That's What I Call Music! 99
Now That's What I Call Music! 100
As opposed to what they get sorted in which is:
Now That's What I Call Music! 10
Now That's What I Call Music! 100
Now That's What I Call Music! 99
I want 100 to follow 99, if that makes sense.
Shawn has given you an explanation of what you see, and a possibility of getting what you desire by writing a custom collation function.
But do you really have albums with names like "Now That's What I Call Music! 10"? My guess is the "10" is some sort of distinguishing code, in which case a better solution is to redesign your database schema to separate out the actual name from the distinguishing code, i.e., two separate columns. That way you can sort on both fields like ORDER BY Album_name, distinguishing code.
(When you create the table you will also probably want the combination of the two fields to be unique, like UNIQUE (Album_name, distinguishing_code))

Report with four tables for each account

I am struggling in the creation of a report including four tables.
Those tables should be the same for each account. I use just one dataset. When I run the report, the data is good, but tables listing appears wrong.
First all BALANCE DETAIL tables for all accounts selected are listed, then all DEBIT TRANSACTION tables for all accounts selected are listed etc.
For each account the page should show up just like this
Please give me an easy-to-understand answer since I am really a beginner in this sector.
It might be easier to this with 5 separate datasets, but I think you can do it with just on also.
Create on 'main' table on the dataset. use 4 detail rows, 1 column
Group it on accountnumber
In each detail of the main table, insert a new table with the same dataset.
Group those sub-tables also on accountnumber
Add a filter to the subtables. set the subtable accountnumber equal to the outer table account number (you can use the expression builder, but it should read something like this: row['ponum'] equals row._outer["ponum"] )
Good luck!

Crystal Report with Multiple Tables - Empty or Cartesian Product

I know this has been asked before..sort of. And that's why I'm posting. Basically I'm building a report in Crystal that relies, to keep this simple, at least 3 tables.
Table A is inner joined to table B by a unique ID. Table B has a child table that may or may not have data related to this unqiue ID.
As a general example table A is a customer table, table B is a product table and the child table is contains the product number. All customers have a product, but not all customers have product number in the child table. I hope I've explained that simply enough.
My issue is sort of between Crytal and Access and how to query this. When I'm writing behind something in VB it's easy enough to write and execute a query and display the result in the desired manner. However I can't seem to get my query straight... I either end up with a report with cartesian product as the resultset, which displays ok...except that even with the few records I have ends up being about 30k pages..or I end up with a blank dataset because the child table does not have corrisponding data to B.
Using outter joins I've managed to get my results within some amount of reason but not acceptable to a real world report. I'm sure this issue has come up but I can't seem to find any suitable answers and to be honest I'm not even sure what questions to ask being a Crystal n00b.
What I'm really after is the data from Table A, the data from Table B and children tables. While they are logically linked and can be linked with the ID field, it isn't necessary I don't think because I am taking a parameter value for the report of the ID field. And once the tables are filtered, no other action needs to be taken except to dump them back on the report.
So can anybody point me in the right direction? Can I set up individual datasoruces (unrelated) based perhaps in a seperate section? Should I build a tree of queries and logic in my DB to get what I need out? I've been racking my brain and can't seem to find the right solution, any and all advice is apreciated and if I can clarify anything or answer any questions I will.
Thanks in advance.
As per requested below:
Section1
ID fname lname
01 john smith
Section2
ID notifiedDate notifiedTime
01 10/10/2012 12:35PM
S2childAdmin
ID noteName
01 jane doe
This data is logically related and can be related in the DB. However it is not necessary as long as the ID parameter is passed to each table. Querying Section1 inner joined with Section2 works fine. But any other arrangements result in more rows than required and I end up with a report many times duplicated. What I really need is something like Section1 joined with Section2 and S2childAdmin as a freely availble table. Otherwise it multiplies my data or results in a null recordset (because it can return 0 rows)
I think this should help point you in the right direction, though it has been 5 years or so since I did heavy Crystal Reports work.
One option might be to join everything using Outer Joins like you stated you were, then use a Crystal Report 'group' on the Table A ID, with a group based upon Table B ID inside of that. So you would, in the actual 'Detail' area put your table C details if there were any, and then use the Group header/footer for Table A and Table B to show data specific to those objects.
Another possible solution that may fall short of your requirements but might get you thinking in another way, is to create your main report and in it, display the fields from table A. Then below those fields include a sub-report and pass in the unique ID from Table A. You will then have a query inside of the subreport that finds all of the Table B records with that Table A.ID value and displays their details.
At this point you run into a weakness of Crystal Reports (at least as of the last version I used) in that you cannot have a subreport inside of a subreport.

Using 'Filter by Column Value' and multi column filtering using a java vector - xPages

I have an xPage which I have built with 3 combo boxes and 1 view control. I would like to use the 'Filter by column value' option within the view control to provide the options to filter the values, allowing the user to display any combination of the combo boxes. e.g. Only comboBox1, or comboBox1 and comboBox2, or comboBox3 only, or comboBox1 and comboBox2 and comboBox3.
I used the example in the 'xPages Demonstration Application' (http://www-10.lotus.com/ldd/ddwiki.nsf/dx/xpagesdemoapp.htm or http://xpagesblog.com/XPagesHome.nsf/Entry.xsp?documentId=AAC8E26599256FDC852578CB0066CC13) to do the multi-column filtering using a vector of non-categorized columns.
So, I have come across what appears to be a fairly major issue whereby the data needs to be sorted by date. Date is not one of the filters, but it needs to be the first column in order for the data to be sorted correctly. So my first column is a string, YYYYMMDD, to ensure the data is sorted correctly. I tried to use the sort option within the view control and that does not appear to work with the column filtering implemented in this manner.
So, as Date one of the criteria I am filtering by, I have passed that as an empty string - using the thought process that an empty string will select all (as in the url examples above).
The code I have used to do the filtering is:
var vtr:java.util.Vector = new java.util.Vector();
var t1 = sessionScope.Email;
var t2 = sessionScope.Own;
var t3 = sessionScope.Module;
vtr.addElement("");
#If(sessionScope.Own=="My calls",vtr.addElement(t1),vtr.addElement(""));
#If(sessionScope.Own=="My calls",vtr.addElement(""),vtr.addElement(t2));
#If(sessionScope.Status=="Open",vtr.addElement("Open"),vtr.addElement(""));
#If(sessionScope.Module=="All",vtr.addElement(""),vtr.addElement(t3));
return vtr;
What I have found is that not all data is being returned. I thought this might be due to the date field. So I removed it (changing the view and removing the first add element), and yet I still find that not all data is being returned. I suspect that this might be due to the empty strings being passed, or, that this does not actually work the way I had hoped.
Does anyone know if I can get this working the way I want it to, and if not, do you have any suggestion on how I can go about this?
Date is not needed as the first sortable column in the view. The first column does need to be sorted for the lookup to work just like the Notes view needs to be sorted for #DbColumn and #DbLookup to work. XPages uses the same underlining architecture. This example - http://dev.openntf.org/demos/demoapp.nsf/viewFilteringVector.xsp - works without the data being sorted by Date.
My guess as to why your example isn't working is down to how your Notes view sorted. Try creating a new view with column 1 (email) ascending sort, column 2 (own) ascending sort, and column 3 (module) again ascending sort. You should be able to get vector filtering working in this situation.
If all that doesn't work for you, you might consider multi-layer category filtering (new to 853). This filtering type in XPages is related to how categoryFilter works but allow you to filter a view by the sub-category (or sub-categories) too. This technique might suit your scenario better. Hope this helps.

Allow users to create new categories and fields on ASP.NET website

We have a db driven asp.net /sql server website and would like to investigate how we can allow users to create a new database category and fields - is this crazy?. Is there any examples of such organic websites out there - the fact that I havent seen any maybe suggest i am?
Interested in the best approach which would allow some level of control by Admin.
I've implemented things along these lines with a dictionary table, rather than a more traditional table.
The dictionary table might look something like this:
create table tblDictionary
(id uniqueidentifier, --Surrogate Key (PK)
itemid uniqueidentifier, --Think PK in a traditional database
colmn uniqueidentifier, --Think "column name" in a traditional database
value nvarchar, --Can hold either string or number
sortby integer) --Sorting columns may or may not be needed.
So, then, what would have been one row in a traditional table would become multiple rows:
Traditional Way (of course I'm not making up GUIDs):
ID Type Make Model Year Color
1 Car Ford Festiva 2010 Lime
...would become multiple rows in the dictionary:
ID ITEMID COLUMN VALUE
0 1 Type Car
1 1 CarMake Ford
2 1 CarModel Festiva
3 1 CarYear 2010
4 1 CarColor Lime
Your GUI can search for all records where itemid=1 and get all of the columns it needs.
Or it can search for all records where itemid in (select itemid from tblDictionary where column='Type' and value='Car' to get all columns for all cars.
In theory, you can put the user-defined types into the same table (Type='Type') as well as the user-defined columns that that Type has (Type='Column', Column='ColumnName'). This is where the sortby column comes into it - to help build the the GUI in the correct order, if you don't want to rely on something else.
A number of times, though, I have felt that storing the user-defined dictionary elements in the dictionary was a bit too much drinking-the-kool-aid. Those can be separate tables because you already know what structure they need at design time. :)
This method will never have the speed or quality of reporting that a traditional table would have. Those generally require the developer to have pre-knowledge of the structures. But if the requirement is flexibility, this can do the job.
Often enough, what starts out as a user-defined area of my sites has had a later project to normalize the data for reporting, etc. But this allows users to get started in a limited way and work out their requirements before engaging the developers.
After all that, I just want to mention a few more options which may or may not work for you:
If you have SharePoint, users already have the ability to create
their own lists in this way.
Excel documents in a shared folder that are saved in such a way
to allow multiple simultaneous edits would also serve the purpose.
Excel documents, stored on the webserver and accessed via ODBC
would also serve as single-table databases like this.

Resources