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How to compare a list of integers in EF Core Interpolated Query

I am trying to convert my sql queries being run with EF Core's .FromSqlRaw() method into queries to be run with .FromSqlInterpolated() so they are less vulnerable to SQL injection attacks. I've gotten almost everything converted and working fine, but the one thing that is stumping me is how to filter by a list of integers in an or configuration on a single field.
The database is postgres, and the quotes are because I used code first EF Core which means that all of the tables are capitalized like the class. ProjectTypeId is an integer column in my table, and projectTypes is a List<int> type variable.
The code in my where clause I'm trying to replace is:
WHERE ""PartGroups"".""ProjectTypeId"" IN({string.Join(",", projectTypes)})
The closest I've been able to get to getting it working is with this:
""PartGroups"".""ProjectTypeId""::text IN({string.Join(",", projectType)})
or
""PartGroups"".""ProjectTypeId""::text LIKE ANY(ARRAY[{string.Join(",", projectTypes)}])
These will work when there is only one value in projectTypes, but any more than that and it fails. I don't know how to view the resulting query + parameter set, just the query, so I'm not sure what's it's doing to the parameter, so I've been struggling to figure out something that works. Also, the query has ~80 parameters total, so manually setting each one with a raw query isn't really feasible.

One way you could approach it, perhaps, is to leverage EF's ability to compose over the top of a raw
context.SomeTable
.FromSqlInterpolated($"SeLeCt t.* FrOm ...")
.Where(st => idList.Contains(st.id))
EF will put your SQL in as a sub query and write the IN for you in the outer. The DB query optimizer will (probably) then push the IN into the sub query if it can..
SELECT ...
FROM
(
SeLeCt t.* FrOm ...
) x
WHERE x.ID IN (.., ..)
If you want to have a look at the SQL EF made and you're on EF5+ the easiest thing to do is do everything apart from ToList/ToArray, and capture the queryable:
var q = context.Thing.Where(...)
Then pause in the debugger and look at the DebugView property of the q. You'll get the full SQL text and you can slot it into SSMS and inspect the execution plan, check it runs the same as a single level (non hierarchical) query..

The other thing you can do, is create your query in a FormattableString yourself. So long as FromSqlInterpolated receives a FormattableString it will pull it apart and parameterize
var args = new object[] { your, single, arguments, here}.Concat(yourListOfThingsHere.Cast<object>()).ToArray();
var fs = FormattableStringFactory.Create(#"SELECT
some,
columns/{0},
here
FROM
table t
WHERE
someColumn = {1} AND
otherColumn BETWEEN {2} and {3} AND
columnToBeINned IN({" + string.Join("},{", Enumerable.Range(4, yourListOfThingsHere.Count)) + #"})
GROUP BY some, columns/{0}", args);
var qq = context.Table.FromSqlInterpolated(fs).Where(m => ...);
It's, of course, possible to write a helper to do this for you...

So I found a way to actually see how EF Core is interpreting the parameters for the interpolated query and was able to play around with it to get what I wanted out of it. So just in case someone wants to or needs to stick to a pure interpolated query, you can use the following pattern for your needs:
WHERE MyTable.MyIntColumn::text LIKE ANY(Array[{string.Join(",", myIntList).Split(",", StringSplitOptions.None)}])
This also works with text values (just no need to cast to text) and you can use wildcards like this:
WHERE MyTable.MyStringColumn ILIKE ANY(ARRAY[{("%" + string.Join("%,%", myStringList) + "%").Split(",", StringSplitOptions.None)}])

Split a string in a linq select expression

The geoStartLoc holds the string in this format "54.5,44.5". I am trying to split and store the results in lat and longitude. I am getting the following error
LINQ to Entities does not recognize the method 'System.String[] Split(Char[])' method, and this method cannot be translated into a store expression. (select statement)
var data = from UberTrip in db.UberTrips
group UberTrip by new { UberTrip.startLoc, UberTrip.geoStartLoc }
into startLocGroup
select new LocationGroup() {
startLocation = startLocGroup.Key.startLoc,
latitude = startLocGroup.Key.geoStartLoc.Split(',').Count().ToString(),
//longitude= startLocGroup.Key.
countTrips = startLocGroup.Count()
};

This is a schema problem in your database. It's bad to ever store delimited values in a column. You should really have two columns: one for geoLatitude, and one for geoLongitude.
But since you probably can't make that change on your own, what you'll need to do is make sure the data is pulled down to your program's code and then split it there. Right now, linq is trying to take the expression tree created by this code and convert it to an SQL query, and it can't do it for the Split() call because not all supported database targets have an analogous Split method available. You need to save that part for after the data is loaded to memory in your program.
To accomplish this, just retrieve the full geoStartLoc string (into an anonymous type if you have to), use .ToList() to force the query compile and retrieve all the data, and then use a .Select() to convert to your LocationGroup objects.

Whenever you get this error message you are performing a query AsQueryable instead of AsEnumerable.
The main difference is that AsQueryable will usually be performed in another process like a database, while AsEnumerable will be performed in-memory in your process.
An IEnumerable object knows how to create an Enumerator. An Enumerator, knows how to do two things: "Give me the first element of your sequence", and "Give me the next element of your sequence (or null if there is no next element).
If your query is AsEnumerable it knows can use all classes and data from your process to create the enumerator. Therefore it can call functions like String.Split.
The AsQueryable does not hold all data to create the enumerator, it holds an Expression and a Provider. The Provider knows where the query needs to be performed on (usually a database, but it can also be a json string or a web service), and it knows how to translate the Expression into a format that the executor understands. In your case, the Provider knows how to translate the Expression into a SQL statement suitable for your database.
Of course SQL does not know your own defined functions. Although there are a lot of .NET functions that can be translated into SQL, not every function can. String.Split is one of them.
See: Supported and Unsupported LINQ Methods (LINQ to Entities)
To solve your problems you could bring the queried data to local memory. This is done using the extension function Enumerable.AsEnumerable(). After that you can use your sequence as if it is an IEnumerable.
The disadvantage of AsEnumerable is that it brings the queried data to local memory. This would be a waste if you remove a lot of this data to create your end result. Therefore make sure that you do your AsEnumerable with not too much data.
Luckily you need the Split in your final Select, so all data you need as input of your final select is thrown away, unless you will do a Skip / Take / FirstOrDefault / etc. In that case it is better to limit your Select by doing your Skip / Take etc before AsEnumerable().
I'm more familiar with MethodSyntax.
Your query divided into smaller steps (if desired make one LINQ):
// still AsQueryable:
var startLocGroups = db.UberTrips
.GroupBy(uberTrip => new {uberTip.startLoc, uberTrip.geoStartLoc)
// make asEnumerable
var localStartLocGroups = startLocGroups.AsEnumerable();
// now you can do your Select
var result = localStartLocGroups
.Select(group => new LocationGroup()
{
startLocation = startLocGroup.Key.startLoc,
latitude = group.Key.geoStartLoc.Split(',')
.Count()
.ToString(),
//longitude= sgroup.Key.
countTrips = group.Count(),
});

Since that isn't supported by the underlying Linq to Entities you'll have to do it after you get the data but before you return the results.
This way you do the query to get the data without invoking the string split function and then modify the results into the proper format.
var data = from UberTrip in db.UberTrips
group UberTrip by new { UberTrip.startLoc, UberTrip.geoStartLoc } into startLocGroup
select new {
startLocation = startLocGroup.Key.startLoc,
geoStartLoc = startLocGroup.Key.geoStartLoc,
countTrips = startLocGroup.Count()
};
return data.Select(trip => new LocationGroup() {
startLocation = trip.startLocation,
latitude = trip.geoStartLoc.Split(',')[0],
longitude= trip.geoStartLoc.Split(',')[1],
countTrips = trip.countTrips
}).ToList();

Linq Check if a string contains any query from a list

I have a list of strings that are search Queries.
I want to see if a string from the database contains anyone of those terms in the Query. I'd like to do this on one line of code, that doesn't make multiple calls to the database. This should work but I want it to be more optimized.
var queries = searchQuery.Trim().Split(' ', StringSplitOptions.RemoveEmptyEntries).Distinct();
var query = context.ReadContext.Divisions.AsQueryable();
queries.ForEach(q => {
query = query.Where(d => (d.Company.CompanyCode + "-" + d.Code).Contains(q));
});
Is there a function that can do this better or a more optimal way of writing that?

There are two issues with your proposed solution:
Most LINQ to SQL providers don't understand string.Contains("xyz") so the provider will either throw an exception or fetch all the data to your machine. The right thing to do is to use SqlMethods.Like as explained in Using contains() in LINQ to SQL
Also, the code you show will check whether the division contains all of the specified strings.
To implement the 'any' behavior you need to construct a custom expression, which will not be possible using plain C#. You would need to look at the System.Linq.Expressions namespace: https://msdn.microsoft.com/en-us/library/system.linq.expressions(v=vs.110).aspx
It is possible, but quite involved.

Expressions in Linq Query

I recently found out that i cannot call any methods from within a linq query. I am trying to write a query that, on the where clause compares two byte arrays. The value on the database is a GUID of type Raw(32) and it is returned as a byte array. This is the record ID for this table. I need to compare it to another byte array. the second byte array could be converted to a string but since i cannot call methods from within linq i was unable to compare.
I tied a custom "Compare" method, i also wrote an extension method. All received an error indicating "LINQ to Entities does not recognize the method"
Here is the code for what i am trying to do. The where clause causes this error:
LINQ to Entities does not recognize the method 'Boolean SequenceEqual[Byte] (System.Collections.Generic.IEnumerable1[System.Byte], System.Collections.Generic.IEnumerable1[System.Byte])' method, and this method cannot be translated into a store expression."
EPSGEntities dbContex = new EPSGEntities();
byte[] byteArray = ParseHex(ViewState["itemID"].ToString());
var q = (from d in dbContex.EPSG_VSOREJECTS
where d.SDSRECID.SequenceEqual(byteArray)
select d).First();

What version of EntityFramework are you using? On EF6 I am able to simply do the following against a SQL 2012 table with a varbinary column:
var q = dbContext.EPSG_VSOREJECTS.FirstOrDefault(e => e.SDSRECID == byteArray);
Is the SDSRECID property on EPSGEntities of type byte[]?
The alternative here would be to go to straight Sql to get your object. Something like:
dbContext.Database.SqlQuery<EPSG_VSOREJECT>("SELECT TOP 1 *" +
"FROM dbo.EPSGEntities" +
"WHERE SDSRECID = #byteString",
new SqlParameter
{
ParameterName = "byteString",
Value = ViewState["itemID"].ToString(),
}).FirstOrDefault();
Linq to Entities in EF is awesome for most queries, but I sometimes drop into sql when I need to do something unsupported, complex, or just fast. Hope this helps!

I'm not entirely sure this works, but I've found calling .AsEnumerable() on the IQueryable object set lets me apply pretty much any code I wish:
var q = dbContex.EPSG_VSOREJECTS.
.AsEnumerable()
.Where(d => d.SDSRECID.SequenceEqual(byteArray));
Doing so seems to prevent EF from trying to translate the Where() clause into SQL syntax, but I have no real idea what the performance hit would/will be.
This is also using method syntax, since I'm not real familiar with query syntax. HTH.
EDIT:
As some others have noted, you have to be careful with how you add any of the iterative methods (AsEnumerable(), ToList(), etc.) since past that point you are no longer building SQL against your data store. Once you start iterating, EF will execute whatever query has been built up to that point, and from then on you are filtering the result set from the LINQ query.
In this case, I don't know that this can be avoided, unless someone can build the same query as a sproc (which EF can execute on your behalf).

Advanced Linq sorting C#

I have an IQueryable that has a list of pages.
I want to do: Pages.OrderByDescending(o => CalculateSort(o.page));
the method calculate sort is similar to that here is a plain english version:
public int calculatesort(page p)
{
int rating = (from r in db.rating select r). sum();
int comments = //query database for comments;
float timedecayfactor = math.exp(-page.totalhoursago);
return sortscore = (rating +comments)* timedecayfactor;
}
when I run a code similar to the one above an error is thrown that the mothode calculatesort cannot be converted to sql.
How can I do a conver the function above to be understood by sql so that I can use it to sort the pages?
Is this not a good approach for large data? Is there another method used to sort sets of results other than dynamically at the database?
I havent slept for days trying to fix this one :(

your code is nowhere near compiling so I'm guessing a lot here but I hope this gives an idea none the less.
As several have posted you need to give Linq-2-Sql an expression tree. Using query syntax that's what happens (by compiler magic)
from p in pages
let rating = (from r in db.rating
where r.PageId == p.PageId
select r.Value).Sum()
let comments = (from c in db.Comments
where c.PageId == p.PageId
select 1).Count()
let timedecayfactor = Math.Exp(-(p.totalhoursago))
orderby (rating + comments)*timedecayfactor descending
select p;
I haven't actually tried this against a database, there's simply too many unknown based on your code, so there might still be stuff that can't be translated.

The error occurs because LINQ cannot convert custom code/methods into SQL. It can convert only Expression<Func<>> objects into SQL.
In your case, you have a complex logic to do while sorting, so it might make sense to do it using a Stored Procedure, if you want to do it in the DB Layer.
Or load all the objects into main memory, and run the calculate sort method on the objects in memory
EDIT :
I don't have the code, so Describing in english is the best I can do :
Have table with structure capable of temporarily storing all the current users data.
Have a calculated field in the Pages table that holds the value calculated from all the non-user specific fields
Write a stored procedure that uses values from these two sources (temp table and calc field) to actually do the sort.
Delete the temp table as the last part in the stored proc
You can read about stored procs here and here

var comments = db.comments.Where(...);
Pages.OrderByDescending(p=>(db.rating.Sum(r=>r.rate) + comments.Count()) * Math.Exp(-p.totalhoursago))

Linq is expecting Calculatesort to return a "queryable" expression in order to generate its own SQL.
In can embed your 'calculatesort' method in this lambda expression. (I replaced your variables with constants in order to compile in my environment)
public static void ComplexSort(IQueryable<string> Pages)
{
Pages.OrderByDescending(p =>
{
int rating = 99;//(from r in db.rating select r). sum();
int comments = 33;//query database for comments;
double timedecayfactor = Math.Exp(88);
return (rating + comments) * timedecayfactor;
});
}
Also, you can even try to run that in parallel (since .net 4.0) replacing the first line with
Pages.AsParallel().OrderByDescending(p =>

Yes, counting previous answers: the LINQ to SQL doesn't know how to translate CalculateSort method. You should convert LINQ to SQL to ordinary LINQ to Object before using custom method.
Try to use this in the way you call the CalculateSort by adding AsEnumerable:
Pages.AsEnumerable().OrderByDescending(o => CalculateSort(o.page));
Then you're fine to use the OrderByDescending extension method.
UPDATE:
LINQ to SQL will always translate the query in the code into Expression tree. It's quite almost the same concept as AST of any programming language. These expression trees are further translated into SQL expression specific to SQL Server's SQL, because currently LINQ to SQL only supports SQL Server 2005 and 2008.