CODEWITHSUNDEEP
c#linq
legendjr
legendjr

Reputation: 276

How do you query several tables at once given a list of table names as strings?

So I work at a company where there are several tables with different names, but the exact same structure (date, time, value). What I would like to be able to do is have my program (C# or LINQ/LINQPad) run through these tables and query out a specific row so I can make sure they have all been updated properly. Is this doable?

So far my train of thought has been this. Knowing that each table name will give it a different class, I'm trying to generically get the values out of the table. I am able to get the table by using the code here

DataContext dc = new DataContext();
var myTable = (ITable)dc.GetType().GetProperty("Table").GetValue(dc, null);

My problem is I'm trying to get the columns out of this table using a similar method. However, the below is throwing an error:

foreach(var e in myTable)
{
    double myValue = (double)e.GetType().GetProperty("Value").GetValue(e, null);
}

So when I took a look all the properties of e.GetType(), I noticed it had 2, one of which was Context, so I went exploring there. However, the next layer down seems to be a dead end of metadata with no actual data coming out of my loop. Am I even heading in the right direction? Once I get this hurdle, it would be easy enough for me to make a list and get my results out that way. Any help would be appreciated. Thanks.

Upvotes: 6

Views: 87

Answers (1)

Yuriy Tseretyan
Yuriy Tseretyan

Reputation: 1716

If you need to query many tables by primary key (EntityKey in db context), then ObjectContext has a method called GetObjectByKey that allows you to get object by EntityKey So, you need to construct just a EntityKey. According to the MSDN article, it is pretty simple,

DataContext dc = new DataContext();
EntityKey key = new EntityKey("DataContext.Table","Id", 123);
dynamic entity = dc.GetObjectByKey(key);

You can create an interface that is common for all tables (entites) that have the same structure and cast your object to the interface, or just use dynamic.

Upvotes: 1

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