I am trying to replicate something that would be simple with a stored procedure.
I have a set of tables like so:
acem__main
acem__child
beta__main
beta_child
xyz__main
xyz__child
In my edmx, I have the acem_main and acem_child linked via a primary/secondary key.
However depending on who logs in I would like to utilise the data of either acem, beta or xyz.
I cannot imagine how to fit this into linq - can anyone help please?
Create a method that returns an IEnumerable and take a user as arguments. In the method, create three Linq queries for acem, beta or xyz and return the result from the query that correspond to the given user.
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I use Entity Framework in combination with an Oracle database. If I create a query like
myLinqStatement.ToListAsync()
I get wrong data returned as a result. If I change the statement to
myLinqStatement.AsNoTracking.ToListAsync()
I get the correct data.
I also checked the native SQL query, which is generated by myLinqStatement.ToListAsync(). The generated SQL query is correct, because I get the correct data.
So is there a problem in the mapping? And why is it working with AsNoTracking?
Thanks!
What AsNoTracking does is to retrieve the data without attaching it to the context, hence any changes you apply over the data do not take effect unless you attach it again so that EF knows it should track its changes.
The code snippets you've provided do not show the whole picture, from the moment a context is created, but is it possible that other parts of your code mutate data before you call myLinqStatement.ToListAsync()?
As you mention that myLinqStatement.AsNoTracking.ToListAsync() returns expected data, makes me assume that there are some side effects in your code that AsNoTracking simply is not aware so just returns whatever it finds in your db
I came across this question because I had a similar issue with Entity Framework Core querying a DB view, the issue was cause because view didn't have a key defined, after defining a key for the entity that map to that DB view, the query returned the same result in both cases (using AsNoTracking or without using it).
In T-SQL a key for a DB view can be defined this way:
CREATE UNIQUE CLUSTERED INDEX UQ_MyDBViewName_ColumnKey
ON dbo.MyDBViewName (ColumnKey);
And in code, you can map the key using the [Key] attribute in the corresponding property of the entity or using the EF fluent API. It will depend of what the project is using.
Either way, using AsNoTracking on a query that goes directly to a DB view makes a lot of sense. Also, if for some reason the query of the view does not allow us to define a key for that view, then the option is to use AsNoTracking.
Hope it helps anyone else having the same issue.
As far as I know, all QuickBase API calls are called using the following syntax: http://<quickbase>/db/<dbid>?
Is there a way to get the dbid field without navigating to that database table within QuickBase?
If the above is not possible, would anyone recommend anything other than creating another table that stores the IDs of the tables you want?
With the latter method, I believe I would only need to store one dbid and could pull down the rest (which I believe would still need to be user entered, but would be better than requiring them to change the code).
Thanks for the help!
API_GetSchema will return the list of dbids.
https://www.quickbase.com/db/<yourApplicationId>?act=API_GetSchema&apptoken=<yourApplicationTokenId>&fmt=flat
I was looking to a Code Road Map feature that Toad provides which shows dependencies of Objects.
Can anyone tell me on what basis the Toad Generate the Dependencies? I am assuming that there is a data dictionary view exists dba_dependencies which work at the backend for getting this relation.
So can we write a script to which we pass object name like package name, table_name amongst others that will show the dependency of the object passed by me.
In code Road Map there is an option to generate data for a table ...how does this work?
What is the algorithm behind it? If there is foreign key on the child table and the parent table is empty, how does this work? How it will populate the depending table first and then the child table.
Looking at user_depencies/ dba_dependencies view structure, querying the view with column REFERENCED_NAME equal to the object that you want to query with should provide you with a list of objects where the object you're searching for is referenced.
Second question is too broad & probably only the Toad developers know how they've implemented it. The data dictionaries provide information about the various constraints on a table. My guess would be the algorithm looks at data dictionary & has different code paths for handling constraints / master child relations. Another assumption would use of handled exceptions to ensure the data is generated cleanly.
I am running a simple LINQ query that connects to a view and returns all of the data with the id that I send in.
My simple query is:
var data = db.ViewDataAlls.Where(x => x.guidRequirementId == guidRequirementId);
if I run this query in the database:
select * from viewDataAll where guidrequiremendid = '{Guid Id Sent In Here}'
I get 2 rows back, however the LINQ query is returning 2 rows, but the rows are a duplicate of the first row, not 2 unique rows.
Any ideas?
EDIT: if I run this LINQ Query:
List<string> nums = db.ViewDataAlls
.Where(x => x.guidRequirementId == guidRequirementId)
.Select(x=>x.strNumber).ToList();
I get the individual row numbers, but if I just try to pull the entire row I get a duplicate of the first row multiple times...
I had the same problem. I was ready to conclude that this was a bug in Linq-to-SQL. Direct SQL queries against the view worked, Linqpad queries worked, etc... but for some reason querying against a view sometimes (and not even very often mind you, but when I'd find a particular value that failed, it appeared to always do so) failed. I verified that the query being passed by Linq to the SQL Server was correct (from the SQLServer logs), so it appeared the results were being mangled when they were received by Linq. Querying directly against the view or accessing the contents of the view via a defined association gave the same bad results.
Realizing that the problem lay on the receiving side of the query (after the results were passed back to Linq), I finally tracked it down to the way I had added the view to the dbml. Originally I had dragged the view onto the dbml designer surface, and added an association to the table I wanted to link it to, a basic one-to-many association (using an basic fkid == id relationship). However I couldn't access the view from the table in code. I discovered that I needed to add a primary key to the child (view), so I set the id property as the PK. This seemed to work until I got an unexpected exception when doing a .SingleOrDefault() against the view through the association. Knowing that it should be impossible for my data to have more that one hit for the property I was filtering with, I ran it through the debugger, and sure enough I was getting the right number of results (2 in my case), but the second result was just a copy of the first. The same thing the OP saw.
The solution it turns out is to set all the fields of the view as part of the primary key (in the dbml; I only had 3). Somehow, having the id field as the lone PK was not sufficient for Linq. Once I did this I had no further problems. (It may not be necessary to designate every field as part of the PK, so you may wish to experiment, but just the one id is insufficient apparently).
Note that I did have the view set as "not unique" in the dbml, which one would think would keep this from happening. Apparently not so.
Is ViewDataAlls a view or a table. If it's a view, maybe the sql statement generating that view produces duplicates.
Thanks JHurdlow, you save my day. Looks like LINQ does not use the groupby or order-by in the views. In my case, the SQL Statement in the view was correct and data was presented very well, but for any reason when use LINQ on my MVC3 is different and duplicates rows. In my case I had a view with 5 tables and I had to put all fields as PK on the view at ___DataModel.edmx. Now works fine.
This solution implies that all fields must be not-null, otherwise has to use CASE NULL-THEN END on the View schema.
I am in the process building myself a simple Linq to SQL repository pattern.
What I wanted to know is, is it possible to set a default sort column so I don't have to call orderby.
From what I have read I don't think it is and if this is the case what would recommend for a solution to this problem.
Would the best idea be to use an attribute on a partial class on my model?
the default order is the clustered index on the table you are pulling from.
What are you wanting to sort on (without sorting on) ?
If you needed something other than having it sorted by the primary key, you could look at supplying a select statement for the table instead of using the runtime generated statement. Look at the properties on the table in the designer -- you should be able to override the runtime generated select, delete, and update statements. I don't personally recommend this, though, since I'm not sure how it will interact with other orderings. I think the intent is more along the lines of allowing you to use stored procedures if you want.
Another alternative would be to create a table-valued function or stored procedure that does the ordering the way you want and has the same schema as the table. If, in the designer, you drag this onto the table, you get a strongly typed method on the data context that you can use to obtain those entities according to the definition of the function/procedure instead of the standard select. Personally I think this introduces fewer maintenance headaches because it makes it more visible, but you do have to remember to use the method instead of the Table property for that entity.