public static IQueryable<SearchProfile> FilterData(string Filter, Repository<SearchProfileContext> dc)
{
IQueryable<SearchProfile> data = null;
var predicate = PredicateBuilder.True<SearchProfile>();
Filter = ExcludedParam(Filter);
if (!string.IsNullOrEmpty(Filter))`enter code here`
{
var stringToSplit = Filter;`enter code here`
List<string[]> arrays = new List<string[]>();
var primeArray = stringToSplit.Split('|');
for (int i = 0; i < primeArray.Length; i++)
{
string first = primeArray[i];
if (first.Contains("chkOrientation") == true)
{
string[] Array = first.Replace("chkOrientation=", "").Split(',');
predicate = predicate.And(a => Array.Contains(a.OrientaionID.ToString()));
}
if (first.Contains("chkProfession") == true)
{
string[] Array = first.Replace("chkProfession=", "").Split(',');
**predicate = predicate.And(a => Array.Contains(SqlFunctions.StringConvert((Double)a.ProfessionID)));**
}
}
data = dc.Select<SearchProfile>().Where(predicate).Distinct();
return data;
}
data = (from a in dc.Select<SearchProfile>().Where(a => a.PersonID > 0) select a).Distinct();
return data;
}
When I ran my program, I got this nasty error below:
LINQ to Entities does not recognize the method Int32 ToInteger(System.Object) method, and this method cannot be translated into a store expression.
then,I used SqlFunctions.StringConvert to make it work but the SQL LINQ generated was not evaluating. This is the sample output (it is comparing '1' and '2' instead of 1 and 2)**
Why are you casting a.ProfessionID to double? What type is a.ProfessionID of?
I think there is implicit conversion to integer, which causes calling the ToInteger method.
And why don't you convert items in Array to integer in the first place, and then use Array of ints in the query?
Related
Currently using:
ASP.NET Core 3.1 / EF Core
C#
Code-first approach
Postgres database
I'm building a method to support column searching on a table. I need to feed the column name to be searched by string value and build a query / lambda that can search the right column. I suspect I need to build some sort of expression and search on the expression but am having trouble with the syntax.
Here's the base code:
string search = "Search Value";
string givenColumn = "search_column";
IQueryable<MyModel> data = _dbContext.table;
data = data.Where(data => data.givenColumn.Contains(search));
I'd like to feed the column name in givenColumn and be able to build a query that searches the right column. At first I thought I wanted reflection but I'm looking to build a SQL query based off of a string, so I think I want to build an expression?
TIA!
Here is some sample code for a runtime WhereContains that operates on string columns:
public static class IQueryableExt {
// String.Contains(string)
static MethodInfo containsMI = typeof(string).GetMethod("Contains", 0, new[] { typeof(string) });
// generate r => r.{columnname}.Contains(value)
static Expression<Func<T, bool>> WhereContainsExpr<T>(string columnname, string value) {
// (T r)
var rParm = Expression.Parameter(typeof(T), "r");
// r.{columnname}
var rColExpr = Expression.Property(rParm, columnname);
// r.{columnname}.Contains(value)
var bodyExpr = Expression.Call(rColExpr, containsMI, Expression.Constant(value));
return Expression.Lambda<Func<T,bool>>(bodyExpr, rParm);
}
public static IQueryable<T> WhereContains<T>(this IQueryable<T> src, string columname, string value) => src.Where(WhereContainsExpr<T>(columname, value));
}
Just pass HTML Table id as a parameter onkeyup method of input field. HTML Code:
<input type="text" id="myInput" class="form-control search-input" onkeyup="searchData('myTable')" placeholder="Search...">
Javascript Code for exact match of any column:
function searchData(tableId) {
// Declare variables
var input, filter, table, tr, i, j, column_length, count_td;
column_length = document.getElementById(tableId).rows[0].cells.length;
input = document.getElementById("myInput");
filter = input.value.toUpperCase();
table = document.getElementById(tableId);
tr = table.getElementsByTagName("tr");
if (filter != "") {
for (i = 1; i < tr.length; i++) { // except first(heading) row
count_td = 0;
for (j = 1; j < column_length - 1; j++) { // except first column
td = tr[i].getElementsByTagName("td")[j];
/* ADD columns here that you want you to filter to be used on */
if (td) {
if (td.innerHTML.toUpperCase() === filter) {
count_td++;
}
}
}
if (count_td > 0) {
tr[i].style.display = "";
} else {
tr[i].style.display = "none";
}
}
}
else {
for (i = 1; i < tr.length; i++) {
tr[i].style.display = "";
}
}
}
***ctx.Load(listItemCollection,
eachItem => eachItem.Include(
item => item,
item => item["Column1"],
item => item["Column2"]
));***
i have list of fields in a array of string instead of column1 and column2, how can i pass it through in include linq, not able to create proper lambda on runtime. i tried following ways but couldn't get success. Static befor loops works but thw fields added in loop fails as it doesn't evaluate string value in loop
***Expression<Func<ListItem, object>>[] paramss = new
Expression<Func<ListItem, object>>[length];
paramss[0] = x => x.ContentType;
paramss[1] = x => x["Title"];
count = 2;
foreach (string item in solConnDefModel.Columns)
{ paramss[count] = x => x[item];
count++;
}***
Please take a reference of below code:
List dlist = context.Web.Lists.GetByTitle("listname");
context.Load(dlist);
context.ExecuteQuery();
string[] fieldNames = { "Id", "Title", "num", "mStartDate" };
// Create the expression used to define the fields to be included
List<Expression<Func<ListItemCollection, object>>> fieldsToBeIncluded = new List<Expression<Func<ListItemCollection, object>>>();
foreach (string s in fieldNames)
{
fieldsToBeIncluded.Add(items => items.Include(item => item[s]));
}
// Initialize the collection of list items
var listItems = dlist.GetItems(new CamlQuery());
context.Load(listItems, fieldsToBeIncluded.ToArray());
context.ExecuteQuery();
You can hover on load method to see what type parameter it requires, then generate a corresponding one and pass it.
i have to create lambda expression at runtime. following code i was able to get expected value
Expression<Func<ListItem, object>>[] paramss = new Expression<Func<ListItem, object>>[length];
foreach (string item in Columns)
{
if (item.ToLower() != "contenttype")
{
ParameterExpression parameter = Expression.Parameter(typeof(ListItem), "x");
var propertyInfo = typeof(ListItem).GetMethod("get_Item");
var arguments = new List<Expression> { Expression.Constant(item) };
var expression = Expression.Call(parameter, propertyInfo, arguments);
var lambda = Expression.Lambda<Func<ListItem, object>>(expression, parameter);
paramss[count] = lambda;
}
else
{
paramss[count] = x => x.ContentType;
}
count++;
}
In my C# application i am using linq. I need a help what is the syntax for if-elseif- using linq in single line. Data, RangeDate are the inputs. Here is the code:
var Date1 = RangeData.ToList();
int record =0;
foreach (var tr in Date1)
{
int id =0;
if (tr.Item1 != null && tr.Item1.port != null)
{
id = tr.Item1.port.id;
}
else if (tr.Item2 != null && tr.Item2.port != null)
{
id = tr.Item2.port.id;
}
if (id >0)
{
if(Data.Trygetvalue(id, out cdat)
{
// Do some operation. (var cdata = SumData(id, tr.item2.port.Date)
record ++;
}
}
}
I think your code example is false, your record variable is initialized to 0 on each loop so increment it is useless .
I suppose that you want to count records in your list which have an id, you can achieve this with one single Count() :
var record = Date1.Count(o => (o.Item1?.port?.id ?? o.Item2?.port?.id) > 0);
You can use following code:
var count = RangeData.Select(x => new { Id = x.Item1?.port?.id ?? x.Item2?.port?.id ?? 0, Item = x })
.Count(x =>
{
int? cdate = null; // change int to your desired type over here
if (x.Id > 0 && Data.Trygetvalue(x.Id, out cdat))
{
// Do some operation. (var cdata = SumData(x.Id, x.Item.Item2.port.Date)
return true;
}
return false;
});
Edit:
#D Stanley is completely right, LINQ is wrong tool over here. You can refactor few bits of your code though:
var Date1 = RangeData.ToList();
int record =0;
foreach (var tr in Date1)
{
int? cdat = null; // change int to your desired type over here
int id = tr.Item1?.port?.id ?? tr.Item2?.port?.id ?? 0;
if (id >0 && Data.Trygetvalue(id, out cdat))
{
// Do some operation. (var cdata = SumData(id, tr.Item2.port.Date)
record ++;
}
}
Linq is not the right tool here. Linq is for converting or querying a collection. You are looping over a collection and "doing some operation". Depending on what that operation is, trying to shoehorn it into a Linq statement will be harder to understand to an outside reader, difficult to debug, and hard to maintain.
There is absolutely nothing wrong with the loop that you have. As you can tell from the other answers, it's difficult to wedge all of the information you have into a "single-line" statement just to use Linq.
I was trying to implement the jQgrid using MvcjQgrid and i got this exception.
System.NotSupportedException was unhandled by user code
Message=The method 'Skip' is only supported for sorted input in LINQ to Entities. The method 'OrderBy' must be called before the method 'Skip'.
Though OrdeyBy is used before Skip method why it is generating the exception? How can it be solved?
I encountered the exception in the controller:
public ActionResult GridDataBasic(GridSettings gridSettings)
{
var jobdescription = sm.GetJobDescription(gridSettings);
var totalJobDescription = sm.CountJobDescription(gridSettings);
var jsonData = new
{
total = totalJobDescription / gridSettings.PageSize + 1,
page = gridSettings.PageIndex,
records = totalJobDescription,
rows = (
from j in jobdescription
select new
{
id = j.JobDescriptionID,
cell = new[]
{
j.JobDescriptionID.ToString(),
j.JobTitle,
j.JobType.JobTypeName,
j.JobPriority.JobPriorityName,
j.JobType.Rate.ToString(),
j.CreationDate.ToShortDateString(),
j.JobDeadline.ToShortDateString(),
}
}).ToArray()
};
return Json(jsonData, JsonRequestBehavior.AllowGet);
}
GetJobDescription Method and CountJobDescription Method
public int CountJobDescription(GridSettings gridSettings)
{
var jobdescription = _dataContext.JobDescriptions.AsQueryable();
if (gridSettings.IsSearch)
{
jobdescription = gridSettings.Where.rules.Aggregate(jobdescription, FilterJobDescription);
}
return jobdescription.Count();
}
public IQueryable<JobDescription> GetJobDescription(GridSettings gridSettings)
{
var jobdescription = orderJobDescription(_dataContext.JobDescriptions.AsQueryable(), gridSettings.SortColumn, gridSettings.SortOrder);
if (gridSettings.IsSearch)
{
jobdescription = gridSettings.Where.rules.Aggregate(jobdescription, FilterJobDescription);
}
return jobdescription.Skip((gridSettings.PageIndex - 1) * gridSettings.PageSize).Take(gridSettings.PageSize);
}
And Finally FilterJobDescription and OrderJobDescription
private static IQueryable<JobDescription> FilterJobDescription(IQueryable<JobDescription> jobdescriptions, Rule rule)
{
if (rule.field == "JobDescriptionID")
{
int result;
if (!int.TryParse(rule.data, out result))
return jobdescriptions;
return jobdescriptions.Where(j => j.JobDescriptionID == Convert.ToInt32(rule.data));
}
// Similar Statements
return jobdescriptions;
}
private IQueryable<JobDescription> orderJobDescription(IQueryable<JobDescription> jobdescriptions, string sortColumn, string sortOrder)
{
if (sortColumn == "JobDescriptionID")
return (sortOrder == "desc") ? jobdescriptions.OrderByDescending(j => j.JobDescriptionID) : jobdescriptions.OrderBy(j => j.JobDescriptionID);
return jobdescriptions;
}
The exception means that you always need a sorted input if you apply Skip, also in the case that the user doesn't click on a column to sort by. I could imagine that no sort column is specified when you open the grid view for the first time before the user can even click on a column header. To catch this case I would suggest to define some default sorting that you want when no other sorting criterion is given, for example:
switch (sortColumn)
{
case "JobDescriptionID":
return (sortOrder == "desc")
? jobdescriptions.OrderByDescending(j => j.JobDescriptionID)
: jobdescriptions.OrderBy(j => j.JobDescriptionID);
case "JobDescriptionTitle":
return (sortOrder == "desc")
? jobdescriptions.OrderByDescending(j => j.JobDescriptionTitle)
: jobdescriptions.OrderBy(j => j.JobDescriptionTitle);
// etc.
default:
return jobdescriptions.OrderBy(j => j.JobDescriptionID);
}
Edit
About your follow-up problems according to your comment: You cannot use ToString() in a LINQ to Entities query. And the next problem would be that you cannot create a string array in a query. I would suggest to load the data from the DB with their native types and then convert afterwards to strings (and to the string array) in memory:
rows = (from j in jobdescription
select new
{
JobDescriptionID = j.JobDescriptionID,
JobTitle = j.JobTitle,
JobTypeName = j.JobType.JobTypeName,
JobPriorityName = j.JobPriority.JobPriorityName,
Rate = j.JobType.Rate,
CreationDate = j.CreationDate,
JobDeadline = j.JobDeadline
})
.AsEnumerable() // DB query runs here, the rest is in memory
.Select(a => new
{
id = a.JobDescriptionID,
cell = new[]
{
a.JobDescriptionID.ToString(),
a.JobTitle,
a.JobTypeName,
a.JobPriorityName,
a.Rate.ToString(),
a.CreationDate.ToShortDateString(),
a.JobDeadline.ToShortDateString()
}
})
.ToArray()
I had the same type of problem after sorting using some code from Adam Anderson that accepted a generic sort string in OrderBy.
After getting this excpetion, i did lots of research and found that very clever fix:
var query = SelectOrders(companyNo, sortExpression);
return Queryable.Skip(query, iStartRow).Take(iPageSize).ToList();
Hope that helps !
SP
I want to do this:
var orderBy = "Nome, Cognome desc";
var timb = time.Timbratures.Include("Anagrafica_Dipendente")
.Where(p => p.CodDipendente == 1);
if(orderBy != "")
timb = timb.OrderBy(orderBy);
Is there an OrderBy overload available that accepts a string parameter?
If you are using plain LINQ-to-objects and don't want to take a dependency on an external library it is not hard to achieve what you want.
The OrderBy() clause accepts a Func<TSource, TKey> that gets a sort key from a source element. You can define the function outside the OrderBy() clause:
Func<Item, Object> orderByFunc = null;
You can then assign it to different values depending on the sort criteria:
if (sortOrder == SortOrder.SortByName)
orderByFunc = item => item.Name;
else if (sortOrder == SortOrder.SortByRank)
orderByFunc = item => item.Rank;
Then you can sort:
var sortedItems = items.OrderBy(orderByFunc);
This example assumes that the source type is Item that have properties Name and Rank.
Note that in this example TKey is Object to not constrain the property types that can be sorted on. If the func returns a value type (like Int32) it will get boxed when sorting and that is somewhat inefficient. If you can constrain TKey to a specific value type you can work around this problem.
Absolutely. You can use the LINQ Dynamic Query Library, found on Scott Guthrie's blog. There's also an updated version available on CodePlex.
It lets you create OrderBy clauses, Where clauses, and just about everything else by passing in string parameters. It works great for creating generic code for sorting/filtering grids, etc.
var result = data
.Where(/* ... */)
.Select(/* ... */)
.OrderBy("Foo asc");
var query = DbContext.Data
.Where(/* ... */)
.Select(/* ... */)
.OrderBy("Foo ascending");
Another solution from codeConcussion (https://stackoverflow.com/a/7265394/2793768)
var param = "Address";
var pi = typeof(Student).GetProperty(param);
var orderByAddress = items.OrderBy(x => pi.GetValue(x, null));
The simplest & the best solution:
mylist.OrderBy(s => s.GetType().GetProperty("PropertyName").GetValue(s));
You don't need an external library for this. The below code works for LINQ to SQL/entities.
/// <summary>
/// Sorts the elements of a sequence according to a key and the sort order.
/// </summary>
/// <typeparam name="TSource">The type of the elements of <paramref name="query" />.</typeparam>
/// <param name="query">A sequence of values to order.</param>
/// <param name="key">Name of the property of <see cref="TSource"/> by which to sort the elements.</param>
/// <param name="ascending">True for ascending order, false for descending order.</param>
/// <returns>An <see cref="T:System.Linq.IOrderedQueryable`1" /> whose elements are sorted according to a key and sort order.</returns>
public static IQueryable<TSource> OrderBy<TSource>(this IQueryable<TSource> query, string key, bool ascending = true)
{
if (string.IsNullOrWhiteSpace(key))
{
return query;
}
var lambda = (dynamic)CreateExpression(typeof(TSource), key);
return ascending
? Queryable.OrderBy(query, lambda)
: Queryable.OrderByDescending(query, lambda);
}
private static LambdaExpression CreateExpression(Type type, string propertyName)
{
var param = Expression.Parameter(type, "x");
Expression body = param;
foreach (var member in propertyName.Split('.'))
{
body = Expression.PropertyOrField(body, member);
}
return Expression.Lambda(body, param);
}
(CreateExpression copied from https://stackoverflow.com/a/16208620/111438)
I did so:
using System.Linq.Expressions;
namespace System.Linq
{
public static class LinqExtensions
{
public static IOrderedQueryable<TSource> OrderBy<TSource>(this IQueryable<TSource> source, string field, string dir = "asc")
{
// parametro => expressão
var parametro = Expression.Parameter(typeof(TSource), "r");
var expressao = Expression.Property(parametro, field);
var lambda = Expression.Lambda(expressao, parametro); // r => r.AlgumaCoisa
var tipo = typeof(TSource).GetProperty(field).PropertyType;
var nome = "OrderBy";
if (string.Equals(dir, "desc", StringComparison.InvariantCultureIgnoreCase))
{
nome = "OrderByDescending";
}
var metodo = typeof(Queryable).GetMethods().First(m => m.Name == nome && m.GetParameters().Length == 2);
var metodoGenerico = metodo.MakeGenericMethod(new[] { typeof(TSource), tipo });
return metodoGenerico.Invoke(source, new object[] { source, lambda }) as IOrderedQueryable<TSource>;
}
public static IOrderedQueryable<TSource> ThenBy<TSource>(this IOrderedQueryable<TSource> source, string field, string dir = "asc")
{
var parametro = Expression.Parameter(typeof(TSource), "r");
var expressao = Expression.Property(parametro, field);
var lambda = Expression.Lambda<Func<TSource, string>>(expressao, parametro); // r => r.AlgumaCoisa
var tipo = typeof(TSource).GetProperty(field).PropertyType;
var nome = "ThenBy";
if (string.Equals(dir, "desc", StringComparison.InvariantCultureIgnoreCase))
{
nome = "ThenByDescending";
}
var metodo = typeof(Queryable).GetMethods().First(m => m.Name == nome && m.GetParameters().Length == 2);
var metodoGenerico = metodo.MakeGenericMethod(new[] { typeof(TSource), tipo });
return metodoGenerico.Invoke(source, new object[] { source, lambda }) as IOrderedQueryable<TSource>;
}
}
}
Use :
example.OrderBy("Nome", "desc").ThenBy("other")
Work like:
example.OrderByDescending(r => r.Nome).ThenBy(r => r.other)
Look at this blog here. It describes a way to do this, by defining an EntitySorter<T>.
It allows you to pass in an IEntitySorter<T> into your service methods and use it like this:
public static Person[] GetAllPersons(IEntitySorter<Person> sorter)
{
using (var db = ContextFactory.CreateContext())
{
IOrderedQueryable<Person> sortedList = sorter.Sort(db.Persons);
return sortedList.ToArray();
}
}
And you can create an EntitiySorter like this:
IEntitySorter<Person> sorter = EntitySorter<Person>
.OrderBy(p => p.Name)
.ThenByDescending(p => p.Id);
Or like this:
var sorter = EntitySorter<Person>
.OrderByDescending("Address.City")
.ThenBy("Id");
You need to use the LINQ Dynamic Query Library in order to pass parameters at runtime,
This will allow linq statements like
string orderedBy = "Description";
var query = (from p in products
orderby(orderedBy)
select p);
If your columnName is in a variable col, then
string col="name";
list.OrderBy(x=>x[col])
As what Martin Liversage said, you can define a Func<>before you pass it to OrderBy method, but I found an interesting way to do that.
You can define a dictionary from string to Func<> like this :
Dictionary<string, Func<Item, object>> SortParameters = new Dictionary<string, Func<Item, object>>()
{
{"Rank", x => x.Rank}
};
And use it like this :
yourList.OrderBy(SortParameters["Rank"]);
In this case you can dynamically sort by string.
In one answer above:
The simplest & the best solution:
mylist.OrderBy(s => s.GetType().GetProperty("PropertyName").GetValue(s));
There is an syntax error, ,null must be added:
mylist.OrderBy(s => s.GetType().GetProperty("PropertyName").GetValue(s,null));