How to use Dynamic LINQ (System.Linq.Dynamic) for LIKE operation?

问题

Can any body tell me how can I use a LIKE operator using System.Linq.Dynamic?

I need to add more than one LIKE expression in my dynamic where query

/*
var query =
db.Customers.
Where("CityName Like @0 or CityName Like @1", "London", "USA")
*/
var query =
db.Customers.
Where("CityName Like @0 or CityName Like @1%", "London", "USA")

thanks heaps

回答1:

Try using simply "CityName.Contains(@1)" this will convert to the proper lambda since its a method invocation on an accessible type.

something like:

var query =
db.Customers.
Where("CityName.Contains(@0) or CityName.Contains(@1)", "London", "USA")

Just tested it with the sample app that comes with the dynamic library and it generates the LIKE operator

回答2:

This will allow the LIKE operator on integer fields:

.Where(searchField + ".ToString().Contains(@0)", searchString);

回答3:

You can use .StartsWith(), .EndsWith() and .Contains() which will generate LIKE SQL with trailing, leading and surrounding wildcards respectively. Don't know of a way to generate a statement with an embedded wildcard tho.

回答4:

Just add more where clauses

var query = db.Customers.Where(c=>c.CityName.contains("London"));
query = query.Where(c=>c.CityName.contains("USA"));
query = query.Where(c=>c.CityName.contains("Johannesburg"));

but the above query will create it :

select * from Customer where CityName like "london" and CityName like "USA" etc...

you want

select * from Customer where CityName like "london" or CityName like "USA" etc...

To use Dynamic Created or statements you can use predicatebuilder there's really alot of functionality there that you can use...

http://www.albahari.com/nutshell/predicatebuilder.aspx

var predicate = PredicateBuilder.False<Customer>();
predicate = predicate.Or(c=>c.CityName.Contains("London"));
predicate = predicate.Or(c=>c.CityName.Contains("USA"));
predicate = predicate.Or(c=>c.CityName.Contains("Johannesburg"));

回答5:

@Jaime that is what i need, thanks.

var query = db.Customers. Where("CityName.Contains(@0) or CityName.Contains(@1)", "London", "USA")

回答6:

you can try this.

IList<string> keyword = new List<string>() { "London", "USA", "Johannesburg" };
            var query = db.Customers.Where(c => keyword.Contains(c.CityName));

来源：https://stackoverflow.com/questions/4599989/how-to-use-dynamic-linq-system-linq-dynamic-for-like-operation

标签

ASP.NET

linq

dynamic-linq