I need a Linq statement that will select all from a table where a field contains all elements in a list<String> while searching other fields for the entire string regardless of words.
It's basically just a inclusive word search on a field where all words need to be in the record and string search on other fields.
Ie I have a lookup screen that allows the user to search AccountID or Detail for the entire search string, or search clientID for words inclusive words, I'll expand this to the detail field if I can figure out the ClientId component.
The complexity is that the AccountId and Detail are being searched as well which Basically stops me from doing the foreach in the second example due to the "ors".
Example 1, this gives me an the following error when I do query.Count() afterwards:
query.Count(); 'query.Count()' threw an exception of type 'System.NotSupportedException' int {System.NotSupportedException}
+base {"Local sequence cannot be used in LINQ to SQL implementations of query operators except the Contains operator."} System.SystemException {System.NotSupportedException}
var StrList = searchStr.Split(' ').ToList();
query = query.Where(p => p.AccountID.Contains(searchStr) || StrList.All(x => p.clientID.Contains(x)) || p.Detail.Contains(searchStr));
Example 2, this gives me an any search word type result:
var StrList = searchStr.Split(' ').ToList();
foreach (var item in StrList)
query = query.Where(p => p.AccountID.Contains(searchStr) || p.clientID.Contains(item) || p.Detail.Contains(searchStr));
Update
I have a table with 3 fields, AccountID, ClientId, Details
Records
Id, AccountID, CLientId, Details
1, "123223", "bobo and co", "this client suxs"
2, "654355", "Jesses hair", "we like this client and stuff"
3, "456455", "Microsoft", "We love Mircosoft"
Search examples
searchStr = "232"
Returns Record 1;
searchStr = "bobo hair"
Returns no records
searchStr = "bobo and"
Returns Record 1
searchStr = "123 bobo and"
Returns returns nothing
The idea here is:
if the client enters a partial AccountId it returns stuff,
if the client wants to search for a ClientId they can type and cancel down clients by search terms, ie word list. due to the large number of clients the ClientID Will need to contain all words (in any order)
I know this seems strange but it's just a simple interface to find accounts in a powerful way.
I think there are 2 solutions to your problem.
One is to count the results in memory like this:
int count = query.ToList().Count();
The other one is to not use All in your query:
var query2 = query;
foreach (var item in StrList)
{
query2 = query2.Where(p => p.clientID.Contains(item));
}
var result = query2.Union(query.Where(p => p.AccountID.Contains(searchStr) || p.Detail.Contains(searchStr)));
The Union at the end acts like an OR between the 2 queries.
Related
Suppose I have a user table with columns id, name, age
With a normal get query User::get(), I get all results with those column's value.
But instead of just getting the id, name, age columns, is it possible if I add another column, perhaps a column with an alias of future_age with a value of age + 1.
The above result could be achieved in SQL like so:
SELECT res.*, (SELECT sum(res.age+1) from users where id = res.id) as future_age from users as res
I've thought about looping through the result and creating new key. but I think this would make the query execution time slow when the data is lengthy.
Is it possible to create the future_age key/column (I don't know the term hehe) directly on the query?
Currently, this is my query:
$user = User::get();
$new_res = []
if($user->count() > 0) {
foreach ($user as $u) {
$u['future_age'] = $u->age + 1
$new_res[] = $u;
}
}
The query works tho, but I don't think this is good if I have a large set of data.
I have some errors using Linq on DataTable and I couldn't figure it out how to solve it. I have to admit that i am pretty new to Linq and I searched the forum and Internet and couldn't figure it out. hope you can help.
I have a DataTable called campaign with three columns: ID (int), Product (string), Channel (string). The DataTable is already filled with data. I am trying to select a subset of the campaign records which satisfied the conditions selected by the end user. For example, the user want to list only if the Product is either 'EWH' or 'HEC'. The selection criteria is dynaically determined by the end user.
I have the following C# code:
private void btnClick()
{
IEnumerable<DataRow> query =
from zz in campaign.AsEnumerable()
orderby zz.Field<string>("ID")
select zz;
string whereClause = "zz.Field<string>(\"Product\") in ('EWH','HEC')";
query = query.Where(whereClause);
DataTable sublist = query.CopyToDataTable<DataRow>();
}
But it gives me an error on line: query = query.Where(whereClause), saying
No property or field 'zz' exists in type 'DataRow'".
If I changed to:
string whereClause = "Product in ('EWH','HEC')"; it will say:
No property or field 'Product' exists in type 'DataRow'
Can anyone help me on how to solve this problem? I feel it could be a pretty simple syntax change, but I just don't know at this time.
First, this line has an error
orderby zz.Field<string>("ID")
because as you said, your ID column is of type int.
Second, you need to learn LINQ query syntax. Forget about strings, the same way you used from, orderby, select in the query, you can also use where and many other operators. Also you'll need to learn the equivalent LINQ constructs for SQL-ish things, like for instance IN (...) is mapped to Enumerable.Contains etc.
With all that being said, here is your query
var productFilter = new[] { "EWH", "HEC" };
var query =
from zz in campaign.AsEnumerable()
where productFilter.Contains(zz.Field<string>("Product"))
orderby zz.Field<int>("ID")
select zz;
Update As per your comment, if you want to make this dynamic, then you need to switch to lambda syntax. Multiple and criteria can be composed by chaining multiple Where clauses like this
List<string> productFilter = ...; // coming from outside
List<string> channelFilter = ...; // coming from outside
var query = campaign.AsEnumerable();
// Apply filters if needed
if (productFilter != null && productFilter.Count > 0)
query = query.Where(zz => productFilter.Contains(zz.Field<string>("Product")));
if (channelFilter != null && channelFilter.Count > 0)
query = query.Where(zz => channelFilter.Contains(zz.Field<string>("Channel")));
// Once finished with filtering, do the ordering
query = query.OrderBy(zz => zz.Field<int>("ID"));
I am trying to select some records using LINQ for Entities (EF4 Code First).
I have a table called Monitoring with a field called AnimalType which has values such as
"Lion,Tiger,Goat"
"Snake,Lion,Horse"
"Rattlesnake"
"Mountain Lion"
I want to pass in some values in a string array (animalValues) and have the rows returned from the Monitorings table where one or more values in the field AnimalType match the one or more values from the animalValues. The following code ALMOST works as I wanted but I've discovered a major flaw with the approach I've taken.
public IQueryable<Monitoring> GetMonitoringList(string[] animalValues)
{
var result = from m in db.Monitorings
where animalValues.Any(c => m.AnimalType.Contains(c))
select m;
return result;
}
To explain the problem, if I pass in animalValues = { "Lion", "Tiger" } I find that three rows are selected due to the fact that the 4th record "Mountain Lion" contains the word "Lion" which it regards as a match.
This isn't what I wanted to happen. I need "Lion" to only match "Lion" and not "Mountain Lion".
Another example is if I pass in "Snake" I get rows which include "Rattlesnake". I'm hoping somebody has a better bit of LINQ code that will allow for matches that match the exact comma delimited value and not just a part of it as in "Snake" matching "Rattlesnake".
This is a kind of hack that will do the work:
public IQueryable<Monitoring> GetMonitoringList(string[] animalValues)
{
var values = animalValues.Select(x => "," + x + ",");
var result = from m in db.Monitorings
where values.Any(c => ("," + m.AnimalType + ",").Contains(c))
select m;
return result;
}
This way, you will have
",Lion,Tiger,Goat,"
",Snake,Lion,Horse,"
",Rattlesnake,"
",Mountain Lion,"
And check for ",Lion," and "Mountain Lion" won't match.
It's dirty, I know.
Because the data in your field is comma delimited you really need to break those entries up individually. Since SQL doesn't really support a way to split strings, the option that I've come up with is to execute two queries.
The first query uses the code you started with to at least get you in the ballpark and minimize the amount of data you're retrieving. It converts it to a List<> to actually execute the query and bring the results into memory which will allow access to more extension methods like Split().
The second query uses the subset of data in memory and joins it with your database table to then pull out the exact matches:
public IQueryable<Monitoring> GetMonitoringList(string[] animalValues)
{
// execute a query that is greedy in its matches, but at least
// it's still only a subset of data. The ToList()
// brings the data into memory, so to speak
var subsetData = (from m in db.Monitorings
where animalValues.Any(c => m.AnimalType.Contains(c))
select m).ToList();
// given that subset of data in the List<>, join it against the DB again
// and get the exact matches this time
var result = from data in subsetData
join m in db.Monitorings on data.ID equals m.ID
where data.AnimalType.Split(',').Intersect(animalValues).Any ()
select m;
return result;
}
How do I search on two combined fields. The search should happen on the SQL end if possible.
So say I have a customer table with first name and last name. I would like users to be able to search on both of those columns using a single search box.
My query currently looks like this:
var query = DbContext.Customers
.Where(c => c.FirstName.Contains(search) || c.LastName.Contains(search));
but it should be something like
var query = DbContext.Customers
.Where(c => c.FullName.Contains(search));
It is not possible unless you have FullName column also mapped. The way around this problem can be String.Concat which is allowed in Linq-to-entities:
var query = DbContext.Customers
.Where(p => String.Concat(p.FirstName, " ", p.LastName)
.Contains(search));
You could use a computed column in the database and map that
e.g.
alter table Customer add FullName AS FirstName + ' ' + LastName
(Not pretty I know)
I am using Linq to Entity Framework 4, what I'm trying to do is build a query that finds all supplier entities that do not start with a letter, typically these are numbers, e.g. "1st Choice" I thought this would be trivial and wrote this:
var letters = Enumerable.Range('A', 26).Select(x => (char)x);
var results = from supplier in All()
where !letters.Contains(supplier.Name[0])
select supplier;
return results.ToList();
Unfortunately this fails with the error:
System.NotSupportedException`
"Unable to create a constant value of type 'System.Char'.
Only primitive types ('such as Int32, String, and Guid') are supported in this context."
Irritatingly this same query works fine in LinqPad as a Linq To Sql query. How can I get around this?
var letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
var results = from supplier in All()
where !letters.Contains(supplier.Name.Substring(0, 1))
select supplier;
Change
var letters = Enumerable.Range('A', 26).Select(x => (char)x);
To
var letters = Enumerable.Range('A', 26).Select(x => ((char)x).ToString());
And
where !letters.Contains(supplier.Name[0])
To
where !letters.Contains(supplier.Name.Substring(0, 1))