LINQ is it possible to add where clauses dynamically

c# entity-framework linq where-clause

Question

I want to search my db with different keys. According to the input, there may be 1 key to 10 keys. Is there a way to add OR/AND clauses to my Linq query dynamically?

 keys[k] // I have my keys in this array 
 var feedList = (from feed in ctx.Feed
                 where feed.content.contains(keys[0]) 
                       && feed.content.contains(keys[1])
                       && ... // continues with the keys.length
                 select new {
                    FeedId = feed.DuyuruId,
                    FeedTitle = feed.FeedTitle,
                    FeedContent = feed.FeedContents,
                    FeedAuthor = user.UserName + " " +User.UserSurname
 }
1
8
1/14/2013 2:18:42 PM

Fastest Entity Framework Extensions

Bulk Insert
Bulk Delete
Bulk Update
Bulk Merge

Accepted Answer

You could try an .All clause to check all the keys:

where keys.All(key => feed.content.contains(key))
13
1/14/2013 2:17:44 PM

Popular Answer

For AND clauses it is simple:

var feedList = from feed in ctx.Feed;
foreach(var key in keys){
    feedList = feedList.Where(x=> content.contains(key));
}
var resultQuery = feedList.Select(x=> new {....});

For OR you will need to use Expressions or try LinqKit and its predicates :

var predicate = PredicateBuilder.False<TypeOfYourEntity>();
foreach(var key in keys){
    predicate = predicate.Or(x=> content.contains(key));
}
var resultQuery = ctx.Feed.Where(predicate).Select(x=> new {....});
mipe34

Related Questions

Building where clauses to evaluate collections inside a many to many connection using LINQ to entities

After reading about the ...PredicateBuilder..., reading all of the wonderful posts that people sent to me, posting on other sites, and then reading more on ...Combining Predicates... and ...Canonical Function Mapping..... oh and I picked up a bit from ...Calling functions in LINQ queries... (some of these classes were taken from these pages). ...I ...
c# entity-framework lambda linq many-to-many
asked by Phobis

In LinQ-to-Entities, adding to the Where clause of an Update

Does the CustomerId help uniquely identify the row past @Id? I didn't really follow the "triggers" bit, since the predicate used for the update is not known by the trigger. Or you do want to re-update the CustomerId each time (detectable from ...UPDATE(...)... in the trigger)...The easiest option is to do it as object updates:...var qry = from prod...
entity-framework linq linq-to-entities sql
asked by Marc Gravell

Using the 'Contains' Clause in Entity Framework instead of the 'IN' SQL Clause

Probably ...this Stackoverflow thread... can help you, at least I think you are looking for this......Excerpt from the thread:...you could implement your own WhereIn method :...public static IQueryable<TEntity> WhereIn<TEntity, TValue> ( this ObjectQuery<TEntity> query, Expression<Func<TEntity, TValue>> selector, IEnumerable<TValu...
asp.net c# contains entity-framework ienumerable
asked by Stephane

Linq: adding conditions to the where clause conditionally

I usually use method chaining but have the same problem. And here is extension I use...public static IQueryable<T> ConditionalWhere<T>( this IQueryable<T> source, Func<bool> condition, Expression<Func<T, bool>> predicate) { if (condition()) { return source.Where(predicate); } ...
entity-framework linq linq-to-sql
asked by Yuriy Granovskiy

What is equivalent to clause between, for comparasion strings in LINQ or lambda expression of?

perpetrators >= and <= are not for strings. they will throw compile time error to you. you can use CompareTo for this as shown below...x.Name.CompareTo(Start) >= 0 && x.Name.CompareTo(End) <= 0
asp.net-mvc-3 c# entity-framework linq razor
asked by Aqdas

Error on Cout but i am not using Count in my LINQ exrpression,

Now with EF6 you can have lambda expressions in your Skip and Take parameters, and in fact its better to do so as the SQL Query is cached and re-used on subsequent pages: ...see this article...But you still need to have evaluated the parameter to pass as @Grant does. So the difference being....Skip(() => skipAmount .Take(() => rows)
asp.net-mvc-5 c# entity-framework-6 linq-to-entities
asked by Peter Kerr

Add object to Entity Framework dynamically using Reflection

You simply need to make a generic method, with a type parameter that represents the type of your entity and use the corresponding DbSet....public int Update<TEntity>(TEntity domainObject) { int id = domainObject.Id; // Needs interface !! using (var context = new MyDbContext()) { var objectInDb = ctx.DbSet<TEntity>.Single(e => e.Id...
c# entity-framework system.reflection
asked by JotaBe

Possible to implement a conditional join clause - JOIN ON condition1 OR condition2?

try giving this a shot:...var isDbTableQuery = dbContext.FirmFeatures.Where(f => f.FeatureId == featureId && f.IsDbTable); var parameters = dbContext.FirmParameters.Where(p => isDbTableQuery.Any() ? p.FeatureId == null : p.FeatureId == featureId); var list = parameters.ToList();
c# entity-framework entity-framework-6 linq sql-server
asked by John

Entity Framework database-first - dynamically adding table to model

I solved this problem adding a column for code prefix and triggers on my base table company for insert update and delete.
c# ef-database-first entity-framework-6
asked by Nurlan

How to add a where clause to Entity Framework query

context.OrderHeaders .Where(o => o.OrderStatus == "NEW") .Join(...
asp.net asp.net-core c# entity-framework-6
asked by Johnathan Barclay

Fastest Entity Framework Extensions

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

Prime Library

Performance

Expression Evaluator

More Projects...

Related

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