Dynamic Linq placeholders don't work properly

c# dynamic-linq linq

Question

I've got the following query:

query.Where("@0 != null && @1.ToString().Contains(@2)", 
            searchedColumnName, searchedColumnName, searchedValue);

And it doesn't work (There are multiple records that should be retreived).

For example, let searchedColumnName == "MY_COLUMN", and searchedValue == "8". When I debug into Dynamic Linq methods, the resulting LambdaExpression expression is:

{Param_0 => ((Convert("MY_COLUMN") != null) AndAlso "MY_COLUMN".ToString().Contains("8"))}

Now, If I don't use placeholders, like:

query.Where(searchedColumnName + " != null && " +
            searchedColumnName + ".ToString().Contains(\"" + searchedValue +"\")");

the LambdaExpression is:

{Param_0 => ((Param_0.MY_COLUMN != null) AndAlso Param_0.MY_COLUMN.ToString().Contains("8"))}

and it works.

I guess it means I use the placeholders incorrectly?

1
0
12/20/2017 8:18:32 AM

Fastest Entity Framework Extensions

Bulk Insert
Bulk Delete
Bulk Update
Bulk Merge

Accepted Answer

Yes, there is a problem with the way you write the placeholder.

Your column name "MY_COLUMN" is considered as the string, not as a column.

So I think, you can not use the placeholder for the column name here. You can use below code:

.Where(searchedColumnName+ " = @0", searchedValue);

For C#6 .Where($"{searchedColumnName} = @0", searchedValue);

Refer this link. It explains the dynamic INQ filter very well:

https://q-a-assistant.info/computer-internet-technology/dynamic-linq-filter-never-retrieves-correct-results-uwp-xaml/676258

1
12/20/2017 8:53:26 AM

Related Questions

Using the System.Linq.Dynamic namespace, how to perform the following in Dynamic Linq

I just want to know how to do the following in Dynamic Linq using System.Linq.Dynamic namespace...var query2 = db.Customers.Select( cust => new Customer { FirstName = cust.FirstName, LastName = cust.LastName Tags="sampleTag,Tag" ...
dynamic-linq linq
asked by emem

Does dynamic GroupBy in dynamic LINQ work with dynamic Where?

I use this ...dynamic LINQ library... together with Linq-to-Entities.... I build query and after that iterate it with ...foreach(object e in query){}...query=db.Table1.Where("it.FieldA>10").Select("it.FieldB");... works....query=db.Table1.Where(e=>e.FieldA>10).GroupBy("it.FieldB", "it").Select("key")... works.... But ...query=db.Table1.Where("it.Fi...
.net dynamic dynamic-linq linq linq-to-entities
asked by alpav

LINQ-to-SQL dynamic table name LINQ-to-SQL

I want to construct my query dynamically based on the contents user has selected, and I want to do this in LINQ-t0-SQL. I have seen ...this..., but I don't want to use SQL statements with datacontext....On Googling a bit I have a feeling that this can be done using dynamic LINQ. Would someone provide an example of similar scenario with dynamic LINQ...
dynamic-linq linq-to-sql
asked by Muhammad Adeel Zahid

Sortable JqGrid with Dynamic LINQ and LINQ to MySQL (DbLinq) - Orderby doesn't work

Try with the following...public ActionResult All(string sidx, string sord, int page, int rows) { IQueryable<Ticket> repository = ZTRepository.GetAllTickets(); int totalRecords = repository.Count(); // first sorting the data as IQueryable<Ticket> without converting ToList() IQueryable<Ticket> orderdData = repository; System.Refl...
c# dblinq dynamic-linq jqgrid linq-to-mysql
asked by Oleg

How can I utilize System.Linq.Dynamic for the LIKE operation?

This will allow the ...LIKE... operator on integer fields:....Where(searchField + ".ToString().Contains(@0)", searchString);
asp.net c# dynamic-linq linq
asked by Dino

Linq to Entities does not function with Dynamic Linq.

I am working on small project which Linq To entities. There is a requirement to filter the data based on the search criteria/filter which is set by the user. Since the filter/search criteria can be for any of the fields which are displayed in the view, I decided to use Dynamic Linq....I downloaded the library from ...Scotgu's blog.... Referenced th...
dynamic-linq linq-to-entities
asked by Madhusudhanan Padmanabhan

OrderBy inside a GroupBy using dynamic LINQ?

I had the following query using normal linq and it was working great (using anonymous type),... var result = from s in Items group s by s.StartTime into groupedItems select new {groupedItems.Key, Items= groupedItems.OrderBy(x => x.Name) }; ...But using Dynamic Linq I cannot get it to order by within the groupby.... r...
dynamic-linq linq linq-to-objects
asked by Martin

Linq to NHibernate and Dynamic LINQ - query caching not working

I have problem with the NHibernate's second level cache. When I use query:... var items1 = Session.Query<Row>() .Cacheable(); .Fetch(x => x.Field) .OrderBy(x => x.Field.Value) .ToList(); ...Everything is fine - the query is cached. But when I want to use Dynamic Linq (...a link...):... va...
dynamic-linq linq linq-to-nhibernate nhibernate
asked by cryss

System.Linq.Dynamic.Core vs System.Linq.Dynamic

What is the difference between System.Linq.Dynamic.Core and System.Linq.Dynamic? I am currently using System.Linq.Dynamic and it does not contain support for ...Select... and ...SelectMany... (among other extension methods). Does System.Linq.Dynamic.Core support these methods?
dynamic-linq
asked by jjf1978

Dynamic Linq 'contains' clause without using placeholder

try code:...int[] ids= {1,2,3,4}; dataContext.Table.Where(c=>c.ids.Contains(t.id)).ToList(); ...Or ...var result= (from p in dataContext.Table.AsEnumerable() join q in ids on p.id equals q select p).Distinct() .ToList();
asp.net asp.net-core-mvc c# dynamic-linq linq
asked by kari kalan

Fastest Entity Framework Extensions

Bulk Insert
Bulk Delete
Bulk Update
Bulk Merge
View more on Stack Overflow

Prime Library

Performance

Expression Evaluator

More Projects...
Licensed under: CC-BY-SA with attribution
Not affiliated with Stack Overflow
Licensed under: CC-BY-SA with attribution
Not affiliated with Stack Overflow