Entity Framework Filtering with a List of String

Question

I want to filter results According to List of strings, something like this:

List<string> filters = {"a", "b", "c", "d"};
var results = (from R in db.Entries 
               where R.word.StartsWith(filters[0])
               ||R.word.StartsWith(filters[1])
               ||R.word.StartsWith(filters[2])
               ||...

I don't know the Length of my filters List so how to Query it dynamically in LINQ?

Thanks in advance.

yup, they are single letters.

Aboud Zakaria
– Aboud Zakaria

2015-03-28 11:46:19 +00:00
Commented Mar 28, 2015 at 11:46 — Aboud Zakaria
– Aboud Zakaria, Commented Mar 28, 2015 at 11:46

Sergey Kalinichenko · Accepted Answer · 2015-03-28 11:24:42Z

6

You should be able to do it like this:

var results = db.Entries 
    .Where(r => filters.Any(f => r.word.StartsWith(f)));

Extension method Any is a way to "fold" a chain of ORs || applied to a list into a single call.

answered Mar 28, 2015 at 11:24

Sergey Kalinichenko

729k85 gold badges1.2k silver badges1.6k bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Philippe Over a year ago

You could also replace Any with All. Any behave like OR and All more like AND.

Pleun · Accepted Answer · 2015-03-28 11:21:38Z

5

This works a little bit different in Linq, kind of the other way around

Use the .Contains()

Something like this:

from r in db.entries
where filters.contains (r.word.substring(0,1))

answered Mar 28, 2015 at 11:21

Pleun

8,9102 gold badges32 silver badges51 bronze badges

2 Comments

Aboud Zakaria Over a year ago

this works great!, but I'm wondering does calling substring(0,1) for every word in database costs much time? I think I will have a performance issue (Entries table contains more than 100k words)

Pleun Over a year ago

You can check the gernerated SQL in Linq to sql

Collectives™ on Stack Overflow

Entity Framework Filtering with a List of String

2 Answers 2

1 Comment

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related