I have a table called Quotes in linq-to-sql that contains 2 columns: author and quote. How do you select both columns of a random row?
Random rand = new Random();
int toSkip = rand.Next(0, context.Quotes.Count);
context.Quotes.Skip(toSkip).Take(1).First();
If you're doing Linq-to-Objects and don't need this to work on SQL, you can use ElementAt() instead of the more verbose Skip(toSkip).Take(1).First() :
var rndGen = new Random(); // do this only once in your app/class/IoC container
int random = rndGen.Next(0, context.Quotes.Count);
context.Quotes.ElementAt(random);
I did it something like this:
list.ElementAt(rand.Next(list.Count());
I stuck a bunch of random operations, including select and shuffle, as extension methods. This makes them available just like all the other collection extension methods.
You can see my code in the article Extending LINQ with Random Operations.
Here is one way to achieve what you want to do:
var quotes = from q in dataContext.Quotes select q;
int count = quotes.Count();
int index = new Random().Next(count);
var randomQuote = quotes.Skip(index).FirstOrDefault();
try it:
list.OrderBy(x => Guid.NewGuid()).Take(1).first();
1 First create a class with rend property
public class tbl_EmpJobDetailsEntity
{
public int JpId { get; set; }
public int rend
{
get
{
Random rnd = new Random();
return rnd.Next(1, 100);
}
}
}
2 Linq query
var rendomise = (from v in db.tbl_EmpJobDetails
select new tbl_EmpJobDetailsEntity
{
JpId=v.JpId
}).OrderBy(o=>o.rend);
Related
I have an MVC application with a dynamic table on one of the pages, which the users defines how many columns the table has, the columns order and where to get the data from for each field.
I have written some very bad code in order to keep it dynamic and now I would like it to be more efficient.
My problem is that I don't know how to define the columns I should get back into my IEnumerable on runtime. My main issue is that I don't know how many columns I might have.
I have a reference to a class which gets the field's text. I also have a dictionary of each field's order with the exact property It should get the data from.
My code should look something like that:
var docsRes3 = from d in docs
select new[]
{
for (int i=0; i<numOfCols; i++)
{
gen.getFieldText(d, res.FieldSourceDic[i]);
}
};
where:
docs = List from which I would like to get only specific fields
res.FieldSourceDic = Dictionary in which the key is the order of the column and the value is the property
gen.getFieldText = The function which gets the entity and the property and returns the value
Obviously, it doesn't work.
I also tried
StringBuilder fieldsSB = new StringBuilder();
for (int i = 0; i < numOfCols; i++)
{
string field = "d." + res.FieldSourceDic[i] + ".ToString()";
if (!string.IsNullOrEmpty(fieldsSB.ToString()))
{
fieldsSB.Append(",");
}
fieldsSB.Append(field);
}
var docsRes2 = from d in docs
select new[] { fieldsSB.ToString() };
It also didn't work.
The only thing that worked for me so far was:
List<string[]> docsRes = new List<string[]>();
foreach (NewOriginDocumentManagment d in docs)
{
string[] row = new string[numOfCols];
for (int i = 0; i < numOfCols; i++)
{
row[i] = gen.getFieldText(d, res.FieldSourceDic[i]);
}
docsRes.Add(row);
}
Any idea how can I pass the linq the list of fields and it'll cut the needed data out of it efficiently?
Thanks, Hoe I was clear about what I need....
Try following:
var docsRes3 = from d in docs
select (
from k in res.FieldSourceDic.Keys.Take(numOfCols)
select gen.getFieldText(d, res.FieldSourceDic[k]));
I got my answer with some help from the following link:
http://www.codeproject.com/Questions/141367/Dynamic-Columns-from-List-using-LINQ
First I created a string array of all properties:
//Creats a string of all properties as defined in the XML
//Columns order must be started at 0. No skips are allowed
StringBuilder fieldsSB = new StringBuilder();
for (int i = 0; i < numOfCols; i++)
{
string field = res.FieldSourceDic[i];
if (!string.IsNullOrEmpty(fieldsSB.ToString()))
{
fieldsSB.Append(",");
}
fieldsSB.Append(field);
}
var cols = fieldsSB.ToString().Split(',');
//Gets the data for each row dynamically
var docsRes = docs.Select(d => GetProps(d, cols));
than I created the GetProps function, which is using my own function as described in the question:
private static dynamic GetProps(object d, IEnumerable<string> props)
{
if (d == null)
{
return null;
}
DynamicGridGenerator gen = new DynamicGridGenerator();
List<string> res = new List<string>();
foreach (var p in props)
{
res.Add(gen.getFieldText(d, p));
}
return res;
}
I have a array of string say:
String[] Fields=new String[]{RowField,RowField1}
In which I can use the below query to get the values by specifying the values is query i.e RowField and RowField1:
var Result = (
from x in _dataTable.AsEnumerable()
select new
{
Name = x.Field<object>(RowField),
Name1 = x.Field<object>(RowField1)
})
.Distinct();
But if suppose I have many values in the Array like:
String[] Fields= new String[]
{
RowField,
RowField1,
RowField2,
.......
RowField1000
};
How can I use the query here without specifying each of the rowfield in the query?
How can i iterate through the array items inside the LINQ?
According to some suggestions in LINQ query and Array of string I am trying to get the result using the code below.
var result = (from row in _dataTable.AsEnumerable()
let projection = from fieldName in fields
select new {Name = fieldName, Value = row[fieldName]}
select projection.ToDictionary(p=>p.Name,p=>p.Value))
.Distinct();
But the problem is it does not return the distinct values.Any ideas?
Start with distinct DataRows by using this overload of Distinct():
_dataTable.AsEnumerable().Distinct(new DataRowEqualityComparer())
Where DataRowEqualityComparer is:
public class DataRowEqualityComparer : IEqualityComparer<DataRow>
{
public bool Equals(DataRow x, DataRow y)
{
return x.ItemArray.SequenceEqual(y.ItemArray);
}
public int GetHashCode(DataRow obj)
{
return string.Join("", obj.ItemArray).GetHashCode();
}
}
I have an array-list that contains some UserID.
I need a query like this:
vat tmp= users.select(a=> a.UserID in (arraylist));
what can I do?
If it's actually in an ArrayList, you should create a List<T> or array first. Then you can use Contains:
// Use the appropriate type, of course.
var ids = arraylist.Cast<string>().ToList();
var tmp = users.Select(a => ids.Contains(a.UserID));
While using Contains on the plain ArrayList may well compile, I would expect it to fail at execution time, assuming users is an IQueryable<>.
List<long> list =new List<long>();
var selected = from n in users where list.Contains(n.ID) select n ;
OR
var selected = users.Where(a=> list.Contains(a.ID)).ToList();
This is the solution I used.
public static IEnumerable<SettingModel> GetSettingBySettingKeys(params string[] settingKey)
{
using (var db = new BoxCoreModelEntities())
{
foreach (var key in settingKey)
{
var key1 = key;
yield return Map(db.Settings.Where(s => s.SettingKey == key1).First());
}
}
}
I am working on a web based application which takes care of online orders placed by customers .
we are using watin for sanity.This is what my code reads
mybrowser.TextField(Find.ByName("searchBox")).Value = "milk";
mybrowser.Image(Find.ByName("search")).Click();
In the input field i want to add any string value(e.g meat/bakery) of X length
Please help
As I read your question you want to be able to generate and input a string of a specific, given length X. Here is some code I wrote a while ago for that.
public static string GetRandomString(int length)
{
StringBuilder randomString = new StringBuilder();
Random randomNumber = new Random();
for (int i = 0; i < length; i++)
{
randomString.Append(Convert.ToChar(Convert.ToInt32(Math.Floor(26 * randomNumber.NextDouble() + 65))));
}
return randomString.ToString();
}
If you want to pick from a specific list of items I would use code like this
public static string GenerateRandomFood()
{
string[] foods = {"Bread", "Cheese", "Milk", };
// There are 3 food names
return foods[GetRandomInt(0, 2)];
}
Hope that is what you are after.
I have got a collection. The coll has strings:
Location="Theater=1, Name=regal, Area=Area1"
Location="Theater=34, Name=Karm, Area=Area4445"
and so on. I have to extract just the Name bit from the string. For example, here I have to extract the text 'regal' and group the query. Then display the result as
Name=regal Count 33
Name=Karm Count 22
I am struggling with the query:
Collection.Location.GroupBy(????);(what to add here)
Which is the most short and precise way to do it?
Yet another Linq + Regex approach:
string[] Location = {
"Theater=2, Name=regal, Area=Area1",
"Theater=2, Name=regal, Area=Area1",
"Theater=34, Name=Karm, Area=Area4445"
};
var test = Location.Select(
x => Regex.Match(x, "^.*Name=(.*),.*$")
.Groups[1].Value)
.GroupBy(x => x)
.Select(x=> new {Name = x.Key, Count = x.Count()});
Query result for tested strings
Once you've extracted the string, just group by it and count the results:
var query = from location in locations
let name = ExtractNameFromLocation(location)
group 1 by name in grouped
select new { Name=grouped.Key, Count=grouped.Count() };
That's not particularly efficient, however. It has to do all the grouping before it does any counting. Have a look at this VJ article for an extension method for LINQ to Objects,
and this one about Push LINQ which a somewhat different way of looking at LINQ.
EDIT: ExtractNameFromLocation would be the code taken from answers to your other question, e.g.
public static string ExtractNameFromLocation(string location)
{
var name = (from part in location.Split(',')
let pair = part.Split('=')
where pair[0].Trim() == "Name"
select pair[1].Trim()).FirstOrDefault();
return name;
}
Here is another LINQ alternative solution with a working example.
static void Main(string[] args)
{
System.Collections.Generic.List<string> l = new List<string>();
l.Add("Theater=1, Name=regal, Area=Area"); l.Add("Theater=34, Name=Karm, Area=Area4445");
foreach (IGrouping<string, string> g in l.GroupBy(r => extractName(r)))
{
Console.WriteLine( string.Format("Name= {0} Count {1}", g.Key, g.Count()) );
}
}
private static string extractName(string dirty)
{
System.Text.RegularExpressions.Match m =
System.Text.RegularExpressions.Regex.Match(
dirty, #"(?<=Name=)[a-zA-Z0-9_ ]+(?=,)");
return m.Success ? m.Value : "";
}