I need a searching process on linq like this. For example, I will make searching on Name column,and user enters "Ca?an" word to textbox. Question mark will e used for sprecial search character for this sitution.
It will search by Name column and, find Canan,Calan,Cazan etc.
I hope I can explain my problem correctly.
Can anyone give me an idea about this linq query. Thank in advance...
You can use this regular expression (if you are using C#) to check for the "Ca?an".
string d = "DDDDDDDDDDCasanDDDDDDDDDD";
Regex r = new Regex(#"Ca([a-zA-Z]{1})an");
string t = r.Match(d).Value;
Output will be:
"Casan"
You have all your colum stored in a database, then do something like:
List<Person> list = new List<Person>(); //Filled
var res = list.Select(x => r.Match(x.Name));
Output will be a IEnumerable with all the "Persons" who contains in the Name "Ca?an", being ? no matter which letter
You need to convert your search-syntax into an existing search-engine - I'd suggest Regex. So the steps will be:
Safely convert the entered search-string into Regex-pattern
Perform the search in Linq on name-property
Solution:
1: Safely convert search string by replacing '?' with Regex-version of wildchar:
var userInput = "Ca?an";
var regexPattern = Regex.Escape(userInput).Replace(#"\?", ".");
2: Perform search in Linq (assuming itemList implements IEnumerable):
var results = itemList.Where(item => Regex.IsMatch(item.Name, regexPattern));
Hope this helps!
Related
I have an array of string
var searchString = new string[] {"1:PS", "2:PS"};
and a large result string eg;
var largeString = "D9876646|10|1:PS^CD9876647100|11|2:PS"
how do I check if any of the options in searchString exist in the largeString?
I know it can be done via loop quite easily but I am looking for an other way around since I need to append the following as search clause in linq query.
You can use LINQ for it with a simple Any() call, like this:
var hasAny = searchString.Any(sub => largeString.Contains(sub));
However, this is as slow as a foreach loop. You can find the answer faster with a regex constructed from searchString:
var regex = string.Join("|", searchString.Select(Regex.Escape));
var hasAny = Regex.IsMatch(largeString, regex);
Depending on the nature of your LINQ provider (assuming it isn't LINQ to Objects), you may want to add individual tests for each member of searchString. The best way to do this is probably using PredicateBuilder
var sq = PredicateBuilder.New<dbType>();
foreach (var s in searchString)
sq = sq.Or(r => r.largeString.Contains(s));
q = q.Where(sq);
Basically all I'm looking to do is something like the following:
string EntityFrameworkType = "Product";
string searchField = "ProductName";
string searchValue = "My Product";
using( var context = new entitycontext())
{
var result = (from x in context.EntityFrameworkType.Where(l=>l.searchField == searchValue) select x).FirstOrDefault();
}
of course this syntax won't work because context does not contain an entity called "EntityFrameworkType"...
Is it possible to do this another way??? What I'm looking to do in generalize my database duplicate check. In this example, I'm searching for any Product with the Name "My Product". But I'd like to be able to pass in these string for say, ProductCategory with ProductCategoryId = 1.... etc...
you can have a look here to get the idea of how it is done.
You'll need to learn about Expression
I have a search page where a user can enter multiple cities seperated by a comma and we need to get all the real estate properties where the city is one that is entered in the search criteria. For instance the user will enter something like this
cities = Dallas, Austin
The query I have works fine if the user enters a full city name
var cityList = new List{"Dallas", "Austin"};
var properties = Reporsitory.AsQueryable
.Where(x=> cityList.Contains(x.City))
.ToList();
However if I just enter Dal, Aus it does not work. How can I make these partial searches work. Is Dynamic LINQ the only answer? Thanks!
try this
var cityList = new List{"Dallas", "Austin"};
var properties = Reporsitory.AsQueryable
.Where(x=> cityList.Contains(y => x.City.Contains(y)).ToList();
try to search inside the string, i hope it works
I don't know specifically for nHibernate, but Linq to SQL does support this:
.Where(x=> x.StartsWith("Dal"))
var properties = Reporsitory.AsQueryable().Where(x => cityList.Count(c => x.StartsWith(c)) != 0);
Or replace StartWith to Contains...
How I can use Like query in LINQ ....
in sql for eg..
name like='apple';
thanks..
Use normal .NET methods. For example:
var query = from person in people
where person.Name.StartsWith("apple") // equivalent to LIKE 'apple%'
select person;
(Or EndsWith, or Contains.) LINQ to SQL will translate these into the appropriate SQL.
This will work in dot notation as well - there's nothing magic about query expressions:
// Will find New York
var query = cities.Where(city => city.Name.EndsWith("York"));
You need to use StartsWith, Contains or EndsWith depending on where your string can appear. For example:
var query = from c in ctx.Customers
where c.City.StartsWith("Lo")
select c;
will find all cities that start with "Lo" (e.g. London).
var query = from c in ctx.Customers
where c.City.Contains("York")
select c;
will find all cities that contain "York" (e.g. New York, Yorktown)
Source
name.contains("apple");
I use item.Contains("criteria"), but, it works efficiently only if you convert to lower both, criteria and item like this:
string criteria = txtSearchItemCriteria.Text.ToLower();
IEnumerable<Item> result = items.Where(x => x.Name.ToLower().Contains(criteria));
I have a need to replace multiple strings with others in a query
from p in dx.Table
where p.Field.Replace("A", "a").Replace("B", "b").ToLower() = SomeVar
select p
Which provides a nice single SQL statement with the relevant REPLACE() sql commands.
All good :)
I need to do this in a few queries around the application... So i'm looking for some help in this regard; that will work as above as a single SQL hit/command on the server
It seems from looking around i can't use RegEx as there is no SQL eq
Being a LINQ newbie is there a nice way for me to do this?
eg is it possible to get it as a IQueryable "var result" say and pass that to a function to add needed .Replace()'s and pass back? Can i get a quick example of how if so?
EDIT: This seems to work! does it look like it would be a problem?
var data = from p in dx.Videos select p;
data = AddReplacements(data, checkMediaItem);
theitem = data.FirstOrDefault();
...
public IQueryable<Video> AddReplacements(IQueryable<Video> DataSet, string checkMediaItem)
{
return DataSet.Where(p =>
p.Title.Replace(" ", "-").Replace("&", "-").Replace("?", "-") == checkMediaItem);
}
Wouldn't it be more performant to reverse what you are trying to do here, ie reformat the string you are checking against rather than reformatting the data in the database?
public IQueryable<Video> AddReplacements(IQueryable<Video> DataSet, string checkMediaItem)
{
var str = checkMediaItem.Replace("-", "?").Replace("&", "-").Replace("-", " "));
return DataSet.Where(p => p.Title == str);
}
Thus you are now comparing the field in the database with a set value, rather than scanning the table and transforming the data in each row and comparing that.