I need to search on multiple columns (LearningModuleDesc and LearningModuleContent which works using the || statements below) but I also need to search on multiple keywords. .Net Core 2.2 and EF Core does not support the string array with Contains (like the example below) but some guidance of how I would go about this would be great.
string[] stringarray = new string[] { "mill", "smith" };
var results = _context.LearningModules
.Where(x => EF.Functions.Contains(x.LearningModuleDesc, stringarray)
|| EF.Functions.Contains(x.LearningModuleContent, stringarray)
);
If I understand correctly, you are looking for something like this
var results = _context.LearningModules.Where(
x => stringarray.Any(t => x.LearningModuleDesc.Contains(t)) ||
stringarray.Any(t => x.LearningModuleContent.Contains(t)))
Related
I have a list of strings like this
"Users": [
"usrName|Fullname|False|0|False|False",
"usrName|Fullname|False|0|False|False",
"usrName|Fullname|False|0|False|False",
"usrName|Fullname|False|0|False|False",
"usrName|Fullname|False|0|False|False",
]
In my episerver/optimizely code I want to match items. I have written this line of code
searchResult.Filter(x => x.Users.MatchContained(k=> k.Split('|')[3], "0"));
I am trying to get all Users where after splitiing on 'pipe' I get 0 at index 3. I am not getting the result, infact I get an exception.
What am I doing wrong here?
Since you left out A LOT of details these are my assumptions
Users is an IList<string> Users
You are trying to get all Users within that list/array where index 3 equals 0
What we don't know is, among others
Is there more than one page instance that have the Users instance filled?
Anyway, this cannot be solved using any Find API with the current system design. Instead you need to rely on linq to parse the result, but then the Find implementation may not be necessary.
var searchClient = SearchClient.Instance;
var search = searchClient.Search<BlogPage>();
var result = search.GetContentResult();
var usersResult = result
.SelectMany(x => x.Users)
.Where(x => x.Split('|')[3].Equals("0"));
This would create and return an object similar to this, since I'm using SelectMany the array would contain all users throughout the systems where there are matched pages from the search result.
If you for whatever reason would like to keep or see some page properties there are alternative approaches where you construct a new object within a select and remove any object where there where not matched users
var searchClient = SearchClient.Instance;
var search = searchClient.Search<BlogPage>();
var result = search.GetContentResult();
var usersResult = result
.Select(p => new
{
PageName = p.Name,
ContentLink = p.ContentLink.ToString(),
Users = p.Users.Where(x => x.Split('|')[3].Equals("0"))
})
.Where(x => x.Users.Any());
If you like to keep using Find for this kind of implementations you must store the data in a better way than strings with delimiters.
am a newbie in linq.. am stuck with one scenario. ie,
i have to sort the search results based on user input.
user inputs are Last Name, First Name and Title. for input 3 drop downs are there and i have to sort result based on the values selected.
i tried
order = Request["orders"].Split(',');
var param = order[0];
var p1 = typeof(Test).GetProperty(param);
param = order[1];
var p2 = typeof(Test).GetProperty(param);
param = order[2];
var p3 = typeof(Test).GetProperty(param);
model.Test = (from tests in model.Test
select tests).
OrderBy(x => p1.GetValue(x, null)).
ThenBy(x => p2.GetValue(x, null)).
ThenBy(x => p3.GetValue(x, null));
but it doesn't works.
i want qry like this
from tests in model.Test
select tests).OrderBy(x => x.lastname).
ThenBy(x => x.firstname).ThenBy(x => x.Title);
order[0]== lastname but how can i use it in the place of OrderBy(x => x.order[0])..?
Thanks in advance.
i solved my case as follows
// list of columns to be used for sorting
List<string>order = Request["orders"].Split(',').ToList();
//map the column string to property
var mapp = new Dictionary<string, Func<Test, string>>
{
{"FirstName", x => x.FirstName},
{"LastName", x => x.LastName},
{"SimpleTitle", x => x.SimpleTitle}
};
//user inputted order
var paras = new List<Func<Test, string>>();
foreach (var para in order)
{
if(!string.IsNullOrEmpty(para))
paras.Add(mapp[para]);
}
//sorting
model.Test= model.Test.OrderBy(paras[0]).ThenBy(paras[1]).ThenBy(paras[2]);
Thanks all,
Actually you are looking for dynamic linq query than you can try out Dynamic LINQ (Part 1: Using the LINQ Dynamic Query Library)
which allow to do like this
it means you can dynamically pass string propertyname to short you collection in orderby function
You can also read about : Dynamic query with Linq
You can compose the expression (any Expression) manually from pieces and then append it to the previous part of query. You can find more info, with example in "Sorting in IQueryable using string as column name".
I have a listbox that I am trying to populate with the result of a SQL Server query via a Entity Framework linq/lambda query. I am feeding the query with a value from a combobox. I keep getting lot of errors like the following: Unable to create a constant value of type 'System.Object'. Only primitive types ('such as Int32, String, and Guid') are supported in this context.
Any suggestions on how to fix this? I just want two fields to populate in a grid
var pAt = ent.Patterns.Where(p => p.Case_Id == (cbCase.SelectedItem as Case).Case_Id).Select(x => new Pattern{ PatternID = x.PatternID, Pattern1 = x.Pattern1 });
listBox1.DataSource = pAt;
listBox1.ValueMember = "PatternID";
listBox1.DisplayMember = "Pattern1";
Try this instead :
var pAt = ent.Patterns.AsEnumerable()
.Where(p => p.Case_Id == ((Case)cbCase.SelectedItem).Case_Id)
.Select(x => new Pattern{ PatternID = x.PatternID, Pattern1 = x.Pattern1 });
Hope this will fix your issue.
Separate the code parts from the SQL parts. Entity Framework can't necessarily construct an SQL query using code objects, but you can usually work around it. Eg:
var caseId = (cbCase.SelectedItem as Case).Case_Id;
var pAt = ent.Patterns.Where(p => p.Case_Id == caseId)
.ToArray()
.Select(x => new Pattern { PatternID = x.PatternID, Pattern1 = x.Pattern1 });
I have a LINQ query where I want to select and read the p.Api value.
var api = DataAccessNew.Instance.dcServers.Where(p => p.Ip == IpAddress).Select(p => p.Api);
How do I read the p.Api value?
I have tried api.ToString() but I get SQL instead of actual column value.
You are getting an IEnumerable<> back (and your ToString call is showing you the value of that expression).
If you are expecting a single value, do this:
var api = DataAccessNew.Instance.dcServers
.Where(p => p.Ip == IpAddress)
.Select(p => p.Api)
.Single();
You might be interested to read about the other methods like Single(): SingleOrDefault, First, FirstOrDefault. Which one you used depends on whether you are expecting a single or multiple values returned (Single vs. First) and what you want to happen if there are no values (the *Default methods will return the type default instead of throwing an exception).
Or if you want to look at all the returned values:
var api = DataAccessNew.Instance.dcServers
.Where(p => p.Ip == IpAddress)
.Select(p => p.Api);
foreach (var apiValue in api)
{
// apiValue will have the value you're looking for.
}
Try this snippet of code:
string apiValue = api.FirstOrDefault().ToString();
your syntex seems ok..
By the way try this
string api =DataAccessNew.Instance.dcServers.Where(p => p.Ip == IpAddress).Select(p => p.Api).FirstOrDefault();
if p.Ip is a unique key in your table you could try to add .FirstOrDefault() after your Linq query.
public string getselectedvalue(ListBox l)
{
string vtext="",vval="";
var selectedQueryText = l.Items.Cast<ListItem>().Where(item => item.Selected);
var selectedQueryVal = l.Items.Cast<ListItem>().Where(item => item.Selected).Select(item => item.Value);
vtext= String.Join("','", selectedQueryText ).TrimEnd();
vval= String.Join("','", selectedQueryVal ).TrimEnd();
return v;
}
I'm having a list of string like
var target = new List<string>() { "C", "C-sharp", "java" };
I'm having a string request = "C is a programming language"
This list should match with the string and should return
C,C-sharp
How can i do this?
here is the solution with linq
var m = from t in target
where t[0] == 'C'
select t;
Using Linq and String.Contains:
var filtered = target.Where(str => str.Contains("C"));
Another option, without Linq, is to change the existing list using List<T>.RemoveAll:
target.RemoveAll(str => !str.Contains("C"));
If you really need a regex (for something more complex), you may also use:
Regex validate = new Regex(".a.", RegexOptions.IgnoreCase);
var filtered = target.Where(str => validate.Match(str).Success);