C# linq to SQL todictionary

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I'm trying to query several tables using linq to sql but can't get the code right - keep getting casting or anonymous type errors. Please can anyone suggest a good sample code, book or tutorial to increase my knowledge?

What I have tried:

C#

public class linqtosql
{
    public Dictionary<int,> dctMC = new Dictionary<int,>();

    public class MC_VARIABLES
    {
        public int ID { get; set; }
        public int UDLY_LAST { get; set; }
        public int STRIKE { get; set; }
        public decimal SKEW_A { get; set; }
        public decimal SKEW_B { get; set; }
        public double SKEW_C { get; set; }
    }

    public void GET_DATA()
    {

        var qryBOOK = from B in Globals.DATA.BOOKs
                      from O in Globals.DATA.OPTIONs
                      from U in Globals.DATA.UDLies
                      from S in Globals.DATA.SKEWs
                      where B.CONTRACT == O.CONTRACT
                      where O.UDLY_SYMBOL == U.UDLY_SYMBOL
                      where O.CONTRACT == S.CONTRACT
                      select new MC_VARIABLES
                      { ID = B.ID, STRIKE = (int)B.STRIKE, SKEW_A = (decimal)S.SKEW_A };

        dctMC = qryBOOK.ToDictionary(x => x.ID, x => x);

        //MC_VARIABLES myThing = dctMC[3];
        //var last = myThing.STRIKE;

        foreach (var item in dctMC)
        {
            MC_VARIABLES myThing = dctMC[item];   !problem here
            var last = myThing.STRIKE;
        }
    }
}

Posted 14-Mar-16 11:18am

Trader999

Updated 15-Mar-16 6:44am

Matt T Heffron

v7

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Comments

Wonde Tadesse 14-Mar-16 22:32pm

The error is not related to toDictonary method. That is perfect. The issue is that there is a cast error around (int)B.STRIKE, SKEW_A = (decimal)S.SKEW_A. Make sure these two variables (B.STRIKE and S.SKEW_A) are cast-able to int and decimal respectively.

3 solutions

Solution 2

First of all, you need to fix your declaration:

C#

public Dictionary<int, MC_VARIABLES> dctMC = new Dictionary<int, MC_VARIABLES>();

Then, you don't need to initialize it here if it always will be initialized in GET_DATA before being referenced. The empty Dictionary created here will be "dropped on the floor" by the assignment in GET_DATA

Posted 14-Mar-16 11:43am

Matt T Heffron

Comments

Sascha Lefèvre 14-Mar-16 18:02pm

+5Additional suggestion for Trader999:
I have a hunch it would make sense making the class linqtosql static, the method GET_DATA static, removing the class-member dctMC and returning qryBOOK.ToDictionary(x => x.ID) from GET_DATA (so changing it from being void to Dictionary<int, MC_VARIABLES>). But as I don't know your intention you have to judge this suggestion.

Matt T Heffron 14-Mar-16 19:09pm

Thanks.
I think I'd opt for making the data a parameter to GET_DATA instead of directly referencing Globals.DATA! (yeech!)

Sascha Lefèvre 14-Mar-16 19:18pm

Yep :)

Solution 1

Just google "c# todictionary" and you'll find usage examples. You need to supply two params, one that lets you know what the key is and one for the value;

http://www.dotnetperls.com/todictionary[^]

Posted 14-Mar-16 11:41am

F-ES Sitecore

Comments

Sascha Lefèvre 14-Mar-16 17:57pm

Not correct, there's a .ToDictionary(..) overload that takes just a KeySelector. The problem here is the missing generic type declaration for the dictionary.

Trader999 14-Mar-16 19:27pm

Thanks for all the input. Matt I have fixed the dictionary declaration, but get funny data in the dictionary (see below) and not the values. I think it has to do with the second parameter in the todictionary line, but I'm not sure how to fix it.

[0] = {[3, nmMONTECARLO.linqtosql+MC_VARIABLES]}

I've tried
dctMC = qryBOOK.ToDictionary(x => x.ID,x=>MC_VARIABLES);
but I'm just hacking and hoping something sticks.

The idea is to query a bunch of tables, save the query in a global dictionary (or class property) and then use the values in the dictionary further in the code.

I've had a look at many many examples on Google, but nothing seems to fit my needs.

Matt I could put the datacontext (Globals.DATA) in the fn GET_DATA, but I will use the datacontext elsewhere in the program and opted for a global datacontext since there will only be on user and getting and saving data will be done sequentially so there shouldn't be a conflict (assuming I understand this correctly!)

Sascha I think you are right to return the query dictionary, this was the next step once I get this working. What is best, return the dictionary as a global variable or save it as a class property?

Matt T Heffron 14-Mar-16 20:56pm

Normally, I would only ~~see~~ be notified of a reply to MY Solution.
I saw this only by "wandering by..."
If you repost some of these comments to my Solution, I can answer them "in context"...

Trader999 14-Mar-16 22:09pm

got the code to work with some other help, but how can I loop through the dictionary? (see edit)

Matt T Heffron 15-Mar-16 12:42pm

Just another suggestion about using Code Project:
Please don't replace a comment with a new one. (minor tweaks are OK...)
Just add a new comment.
That way the whole history of the discussion remains for everything to be read in context.

Trader999 14-Mar-16 23:36pm

Matt I got the code to work, but I'm still interested to know why I shouldn't directly reference Globals.Data.

Matt T Heffron 15-Mar-16 12:39pm

The argument against Globals.DATA is against using any global data in general, and specifically against having a global connection to a database kept open.
See @OriginalGriff's comments here

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Trader999 · Accepted Answer · 2016-03-14T17:35:00

here is a final solution.

C#

public class linqtosql
   {
       public Dictionary<int, MC_VARIABLES> dctMC = new Dictionary<int, MC_VARIABLES>();

       public class MC_VARIABLES
       {
           public int ID { get; set; }
           public int UDLY_LAST { get; set; }
           public int STRIKE { get; set; }
           public decimal SKEW_A { get; set; }
           public decimal SKEW_B { get; set; }
           public double SKEW_C { get; set; }
       }

       public void GET_DATA()
       {

           var qryBOOK = from B in Globals.DATA.BOOKs
                         from O in Globals.DATA.OPTIONs
                         from U in Globals.DATA.UDLies
                         from S in Globals.DATA.SKEWs
                         where B.CONTRACT == O.CONTRACT
                         where O.UDLY_SYMBOL == U.UDLY_SYMBOL
                         where O.CONTRACT == S.CONTRACT
                         select new MC_VARIABLES
                         { ID = B.ID, STRIKE = (int)B.STRIKE, SKEW_A = (decimal)S.SKEW_A };

           dctMC = qryBOOK.ToDictionary(x => x.ID, x => x);

           foreach (KeyValuePair<int, MC_VARIABLES> KVP in dctMC)
           {
               var key = KVP.Key;
               var item = KVP.Value.SKEW_A;
           }
       }
   }

C# linq to SQL todictionary

3 solutions

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