I'm using the EntityFramework and the library 'System.Linq.Dynamic.Core' for dynamically selecting records based upon an array of values.
It works fine for int[] but it returns funky SQL with string[].
var whereQuery = _context.Registrations.AsQueryable();
int[] intArray = new[] {1, 2, 3};
string[] array = new[] {"A001", "D444"};
whereQuery = whereQuery.Where($"#0.Contains(RegistrationId)", intArray);
whereQuery = whereQuery.Where($"#0.Contains(Code)", array);
When debugging I see it generated the following SQL statment
...
FROM [dbo].[Registrations] AS [Extent1]
WHERE ([Extent1].[RegistrationId] IN (1, 2, 3))
AND (( CAST(CHARINDEX([Extent1].[Code], N'A001') AS int)) > 0)
For the int[] it generates the correct / expected "IN-statement".
For the string[] it only checks for the first value from the array. I would expect:
AND ([Extent1].[Code] IN (N'A001', N'D444'))
Versions :
System.Linq.Dynamic.Core v1.0.14.0 (runtime v4.0.30319)
EntiftyFramework v6.0.0.0
What I am I missing?
using List<string> instead of an string[] solves the problem.
For more information also see :
https://github.com/StefH/System.Linq.Dynamic.Core/issues/61
This is not a bug.
The reason is that you test fails because you provide an array in the
Where clause as the params.. This actually means that if you provide
an array like { "A001", "D444" }, the code tries to replace #0 by "A001",
and tries to replace #1 by "D444" and so on. But you only have defined
#0.
Reply to "Not a bug" above.
Yes, my sample displays two times #0. This is just sample code that I copied. The error remains even when using only 1 parameter.
Related
The following code is giving the above error, and I cannot figure out why:
var x = _sqlConn.Connection().QueryResults<Results>("MyDb.dbo.get_records", new { id = theId });
int retVal = x.Outputs.Return_Value;
if (retVal == 0) // ...meaning result set was also returned...fine to this point.
{
var list = x.Outputs.Set1; // exception thrown here with above error
var temp = list.FirstOrDefault();
I have been using other features of Insight.Database for a number of years, but have not had to retrieve a SQL RETURN value at the same time as a recordset. The SQL itself works correctly in SSMS, returning a result set and the RETURN value of 0, as expected. This is happening in VS2019, .NET 4 and .NET 4.5.2; Insight.Database 5.2.7 and 5.2.8.
I got this code from the following page:
https://github.com/jonwagner/Insight.Database/wiki/Specifying-Result-Structures
where it shows this:
var results = connection.QueryResults<Beer, Glass>("GetAllBeersAndAllGlasses");
IList<Beer> beers = results.Set1;
which I combined with the following code from here:
https://github.com/jonwagner/Insight.Database/wiki/Output-Parameters
var results = connection.QueryResults<Results>("MyProc", inputParameters);
var p = results.Outputs.p;
That part works. It's accessing .Set1 that is failing, and I am not sure how to track down why.
I do not have experience with the FastExpando class, but Jon promised magic, and I want to believe. Thanks for any help.
I haven’t tried results+dynamic objects in a while…
I think it is because you are doing:
QueryResults<Results> and Results is an Insight type
You probably want:
QueryResults<MyType>
And then you get back a Results<MyType>
Which contains the return val and Set1
If not, post a ticket over on github and we will help you out.
My Linq Query keeps returning the null error on FirstOrDefault
The cast to value type 'System.Int32' failed because the materialized value is null
because it can't find any records to match on the ClinicalAssetID form the ClinicalReading Table, fair enough!
But I want the fields in my details page just to appear blank if the table does not have matching entry.
But how can I handle the null issue when using the order by function ?
Current Code:
var ClinicalASSPATINCVM = (from s in db.ClinicalAssets
join cp in db.ClinicalPATs on s.ClinicalAssetID equals cp.ClinicalAssetID into AP
from subASSPAT in AP.DefaultIfEmpty()
join ci in db.ClinicalINSs on s.ClinicalAssetID equals ci.ClinicalAssetID into AI
from subASSINC in AI.DefaultIfEmpty()
join co in db.ClinicalReadings on s.ClinicalAssetID equals co.ClinicalAssetID into AR
let subASSRED = AR.OrderByDescending(subASSRED => subASSRED.MeterReadingDone).FirstOrDefault()
select new ClinicalASSPATINCVM
{
ClinicalAssetID = s.ClinicalAssetID,
AssetTypeName = s.AssetTypeName,
ProductName = s.ProductName,
ModelName = s.ModelName,
SupplierName = s.SupplierName,
ManufacturerName = s.ManufacturerName,
SerialNo = s.SerialNo,
PurchaseDate = s.PurchaseDate,
PoNo = s.PoNo,
Costing = s.Costing,
TeamName = s.TeamName,
StaffName = s.StaffName,
WarrantyEndDate = subASSPAT.WarrantyEndDate,
InspectionDate = subASSPAT.InspectionDate,
InspectionOutcomeResult = subASSPAT.InspectionOutcomeResult,
InspectionDocumnets = subASSPAT.InspectionDocumnets,
LastTypeofInspection = subASSINC.LastTypeofInspection,
NextInspectionDate = subASSINC.NextInspectionDate,
NextInspectionType = subASSINC.NextInspectionType,
MeterReadingDone = subASSRED.MeterReadingDone,
MeterReadingDue = subASSRED.MeterReadingDue,
MeterReading = subASSRED.MeterReading,
MeterUnitsUsed = subASSRED.MeterUnitsUsed,
FilterReplaced = subASSRED.FilterReplaced
}).FirstOrDefault(x => x.ClinicalAssetID == id);
Tried this but doesn't work
.DefaultIfEmpty(new ClinicalASSPATINCVM())
.FirstOrDefault()
Error was:
CS1929 'IOrderedEnumerable<ClinicalReading>' does not contain a definition for 'DefaultIfEmpty' and the best extension method overload 'Queryable.DefaultIfEmpty<ClinicalASSPATINCVM>(IQueryable<ClinicalASSPATINCVM>, ClinicalASSPATINCVM)' requires a receiver of type 'IQueryable<ClinicalASSPATINCVM>'
Feel a little closer with this but still errors
let subASSRED = AR.OrderByDescending(subASSRED => (subASSRED.MeterReadingDone != null) ? subASSRED.MeterReadingDone : String.Empty).FirstOrDefault()
Error:
CS0173 Type of conditional expression cannot be determined because there is no implicit conversion between 'System.DateTime?' and 'string'
The original error means that some of the following properties of the ClinicalASSPATINCVM class - MeterReadingDone, MeterReadingDue, MeterReading, MeterUnitsUsed, or FilterReplaced is of type int.
Remember that subASSRED here
let subASSRED = AR.OrderByDescending(subASSRED => subASSRED.MeterReadingDone).FirstOrDefault()
might be null (no corresponding record).
Now look at this part of the projection:
MeterReadingDone = subASSRED.MeterReadingDone,
MeterReadingDue = subASSRED.MeterReadingDue,
MeterReading = subASSRED.MeterReading,
MeterUnitsUsed = subASSRED.MeterUnitsUsed,
FilterReplaced = subASSRED.FilterReplaced
If that was LINQ to Objects, all these would generate NRE (Null Reference Exception) at runtime. In LINQ to Entities this is converted and executed as SQL. SQL has no issues with expression like subASSRED.SomeProperty because SQL supports NULL naturally even if SomeProperty normally does not allow NULL. So the SQL query executes normally, but now EF must materialize the result into objects, and the C# object property is not nullable, hence the error in question.
To solve it, find the int property(es) and use the following pattern inside query:
SomeIntProperty = (int?)subASSRED.SomeIntProperty ?? 0 // or other meaningful default
or change receiving object property type to int? and leave the original query as is.
Do the same for any non nullable type property, e.g. DateTime, double, decimal, Guid etc.
You're problem is because your DefaultIfEmpty is executed AsQueryable. Perform it AsEnumerable and it will work:
// create the default element only once!
static readonly ClinicalAssPatInVcm defaultElement = new ClinicalAssPatInVcm ();
var result = <my big linq query>
.Where(x => x.ClinicalAssetID == id)
.AsEnumerable()
.DefaultIfEmpty(defaultElement)
.FirstOrDefault();
This won't lead to a performance penalty!
Database management systems are extremely optimized for selecting data. One of the slower parts of a database query is the transport of the selected data to your local process. Hence it is wise to let the DBMS do most of the selecting, and only after you know that you only have the data that you really plan to use, move the data to your local process.
In your case, you need at utmost one element from your DBMS, and if there is nothing, you want to use a default object instead.
AsQueryable will move the selected data to your local process in a smart way, probably per "page" of selected data.
The page size is a good compromise: not too small, so you don't have to ask for the next page too often; not too large, so that you don't transfer much more items than you actually use.
Besides, because of the Where statement you expect at utmost one element anyway. So that a full "page" is fetched is no problem, the page will contain only one element.
After the page is fetched, DefaultIfEmpty checks if the page is empty, and if so, returns a sequence containing the defaultElement. If not, it returns the complete page.
After the DefaultIfEmpty you only take the first element, which is what you want.
I am trying to get some random items from the database using the Sample() method. I updated to the latest version of the driver and copied the using statements from the linked example. However, something isn't working, and I am hoping it's some simple mistake on my part. All the relevant information is in the image below:
Edit:
Greg, I read the aggregation docs here and the raw db method doc here, but I still don't get it. Last two lines are my attempts, I have never used aggregation before:
var mongoCollection = GetMongoCollection<BsonDocument>(collectionName);
long[] locationIds = new long[] { 1, 2, 3, 4, 5 };
var locationsArray = new BsonArray();
foreach (long l in locationIds) { locationsArray.Add(l); };
FilterDefinition<BsonDocument> sampleFilter = Builders<BsonDocument>.Filter.In("LocationId", locationsArray);
var findSomething = mongoCollection.Find(sampleFilter); //this works, the two attempts below don't.
var aggregateSomething = mongoCollection.Aggregate(sampleFilter).Sample(25);
var aggregateSomething2 = mongoCollection.Aggregate().Match(sampleFilter).Sample(25);
Sample is only available from an aggregation. You need to start with Aggregate, not Find. I believe it's also available in Linq.
UPDATE:
Looks like we don't have a method for it specifically. However, you can use the AppendStage method.
mongoCollection.Aggregate(sampleFilter)
.AppendStage<BsonDocument>("{ $sample: { size: 3 } }");
I can't find how to do check with assertj the following (which is very common):
Suppose I have:
result1 = {"AAA", "BBB"}
result2 = {"DDD"}
I want to check the values in result is one of these:
String[] valid = String[]{"AAA", "BBB", "CCC"};
using assertj, whould be something as:
assertThat(result1).xxxx(valid);
assertThat(result2).xxxx(valid);
So that result1 would pass check, but result2 not.
contains() does not work (it checks that result contains all valid elements)
I don't want have to create a custom condition for this kind of checking
Any idea?
You can wtite it the other way around:
assertThat(valid).contains(result1);
assertThat(valid).contains(result2);
If you insist on having the result on the left and valid on the right side, you can use:
assertThat(result1).isSubsetOf(Arrays.asList(valid));
assertThat(result2).isSubsetOf(Arrays.asList(valid));
Or, why not to define the valid as a set, rather than an array?
Set<String> valid = Sets.newHashSet("AAA", "BBB", "CCC"); //Sets comes from google guava
assertThat(result1).isSubsetOf(valid);
assertThat(result2).isSubsetOf(valid);
I'm using Rails 4 in a web app, Postgresql database and squeel gem for queries.
I have this function in my model statistic.rb
def properties_mean_ppm(mode, rooms, type, output_currency_id)
sql_result = properties(mode, rooms, type).select{
avg(price_dolar / property_area).as(prom)
}
avg = sql_result[0].prom
final_avg = change_currency(avg, DOLAR_ID, output_currency_id)
return final_avg.to_f
end
price_dolar and property_area are columns in the properties table.
It works fine in Rails console and displays the result, but when I use it on the controller it gives an error:
ActiveModel::MissingAttributeError (missing attribute: id)
And indicates the line
avg = sql_result.to_a[0].prom
I also tried using sql_result[0].prom or sql_result.take or sql_result.first, they all have the same error.
The sql_result is this:
#<ActiveRecord::Relation [#<Property >]>
This is the action called in the controller
def properties_mean_ppm
#statistic = Statistic.find(params[:id])
mode = params[:mode] ? params[:mode] : ANY_MODE
type = params[:type] ? params[:type] : ANY_TYPE
one_room = #statistic.properties_mean_ppm(mode, 1, type, UF)
end
I know how to get the result using only SQL without activerecord but that would be very inefficient for me because I have lots of filters called before in the properties() function
Seems like calling that from the properties object made the controller to expect a Property with an id as a result. So I made it work without squeel.
sql_result = properties(mode, rooms, type).select(
"avg(precio_dolar / dimension_propiedad) as prom, 1 as id"
)
And giving a fixed id to the result