How can I do an OrderBy with a dynamic string parameter

Question

I want to do this   var orderBy    Nome  Cognome desc    var timb   time Timbratures Include  Anagrafica Dipendente        Where p   gt  p CodDipendente    1    if orderBy            timb   timb OrderBy orderBy     Is there an OrderBy overload available that accepts a string parameter

User · Answer

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);

User · Answer

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

User · Answer

I did so   using System Linq Expressions   namespace System Linq       public static class LinqExtensions                public static IOrderedQueryable lt TSource gt  OrderBy lt TSource gt  this IQueryable lt TSource gt  source  string field  string dir    asc                            parametro   gt  express  o             var parametro   Expression Parameter typeof TSource    r                var expressao   Expression Property parametro  field               var lambda   Expression Lambda expressao  parametro      r   gt  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   gt  m Name    nome  amp  amp  m GetParameters   Length    2               var metodoGenerico   metodo MakeGenericMethod new     typeof TSource   tipo                 return metodoGenerico Invoke source  new object     source  lambda    as IOrderedQueryable lt TSource gt                       public static IOrderedQueryable lt TSource gt  ThenBy lt TSource gt  this IOrderedQueryable lt TSource gt  source  string field  string dir    asc                         var parametro   Expression Parameter typeof TSource    r                var expressao   Expression Property parametro  field               var lambda   Expression Lambda lt Func lt TSource  string gt  gt  expressao  parametro      r   gt  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   gt  m Name    nome  amp  amp  m GetParameters   Length    2               var metodoGenerico   metodo MakeGenericMethod new     typeof TSource   tipo                 return metodoGenerico Invoke source  new object     source  lambda    as IOrderedQueryable lt TSource gt                        Use    example OrderBy  Nome    desc   ThenBy  other     Work like   example OrderByDescending r   gt  r Nome  ThenBy r   gt  r other

User · Answer

You don t need an external library for this  The below code works for LINQ to SQL entities            lt summary gt          Sorts the elements of a sequence according to a key and the sort order           lt  summary gt           lt typeparam name  TSource  gt The type of the elements of  lt paramref name  query    gt   lt  typeparam gt           lt param name  query  gt A sequence of values to order  lt  param gt           lt param name  key  gt Name of the property of  lt see cref  TSource   gt  by which to sort the elements  lt  param gt           lt param name  ascending  gt True for ascending order  false for descending order  lt  param gt           lt returns gt An  lt see cref  T System Linq IOrderedQueryable 1    gt  whose elements are sorted according to a key and sort order  lt  returns gt      public static IQueryable lt TSource gt  OrderBy lt TSource gt  this IQueryable lt TSource gt  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

User · Answer

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 lt TSource  TKey gt  that gets a sort key from a source element  You can define the function outside the OrderBy   clause   Func lt Item  Object gt  orderByFunc   null    You can then assign it to different values depending on the sort criteria   if  sortOrder    SortOrder SortByName    orderByFunc   item   gt  item Name  else if  sortOrder    SortOrder SortByRank    orderByFunc   item   gt  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

User · Answer

Look at this blog here  It describes a way to do this  by defining an EntitySorter lt T gt    It allows you to pass in an IEntitySorter lt T gt  into your service methods and use it like this   public static Person   GetAllPersons IEntitySorter lt Person gt  sorter        using  var db   ContextFactory CreateContext                  IOrderedQueryable lt Person gt  sortedList   sorter Sort db Persons            return sortedList ToArray              And you can create an EntitiySorter like this   IEntitySorter lt Person gt  sorter   EntitySorter lt Person gt       OrderBy p   gt  p Name       ThenByDescending p   gt  p Id     Or like this   var sorter   EntitySorter lt Person gt        OrderByDescending  Address City         ThenBy  Id

User · Answer

The simplest  amp  the best solution   mylist OrderBy s   gt  s GetType   GetProperty  PropertyName   GetValue s

User · Answer

Another solution from codeConcussion  https   stackoverflow com a 7265394 2793768   var param    Address       var pi   typeof Student  GetProperty param       var orderByAddress   items OrderBy x   gt  pi GetValue x  null

User · Answer

In one answer above   The simplest  amp  the best solution   mylist OrderBy s   gt  s GetType   GetProperty  PropertyName   GetValue s      There is an syntax error   null must be added   mylist OrderBy s   gt  s GetType   GetProperty  PropertyName   GetValue s null

[linq] How can I do an OrderBy with a dynamic string parameter?

Examples related to linq

Examples related to sql-order-by