convert a list of objects from one type to another using lambda expression

Question

I have a foreach loop reading a list of objects of one type and producing a list of objects of a different type  I was told that a lambda expression can achieve the same result   var origList   List lt OrigType gt        assume populated var targetList   List lt TargetType gt       foreach OrigType a in origList        targetList Add new TargetType    SomeValue   a SomeValue        Any help would be appreciated- i m new to lambda and linq  thanks  s

User · Answer

If the types can be directly cast this is the cleanest way to do it:

var target = yourList.ConvertAll(x => (TargetType)x);

If the types can't be directly cast then you can map the properties from the orginal type to the target type.

var target = yourList.ConvertAll(x => new TargetType { SomeValue = x.SomeValue });

User · Answer

for similar type class   List lt targetlist gt  targetlst  JsonConvert DeserializeObject lt List lt targetlist gt  gt  JsonConvert SerializeObject  lt List lt baselist gt

User · Answer

We will consider first List type is String and want to convert it to Integer type of List   List lt String gt  origList   new ArrayList lt  gt        assume populated   Add values in the original List   origList add  1    origList add  2        origList add  3        origList add  4        origList add  8      Create target List of Integer Type  List lt Integer gt  targetLambdaList   new ArrayList lt Integer gt     targetLambdaList origList stream   map Integer  valueOf  collect Collectors toList       Print List values using forEach       targetLambdaList forEach System out  println

User · Answer

Or with a constructor  amp  linq with Select   public class TargetType     public string Prop1  get set     public string Prop1  get set         Constructor   public TargetType OrigType origType        Prop1   origType Prop1      Prop2   origType Prop2         var origList   new List lt OrigType gt     var targetList   origList Select s  gt  new TargetType s   ToList        The Linq line is more soft   -

User · Answer

Try the following  var targetList   origList    Select x   gt  new TargetType     SomeValue   x SomeValue       ToList      This is using a combination of Lambdas and LINQ to achieve the solution   The Select function is a projection style method which will apply the passed in delegate  or lambda in this case  to every value in the original collection   The result will be returned in a new IEnumerable lt TargetType gt    The  ToList call is an extension method which will convert this IEnumerable lt TargetType gt  into a List lt TargetType gt

User · Answer

If you need to use a function to cast   var list1   new List lt Type1 gt     var list2   new List lt Type2 gt      list2   list1 ConvertAll x   gt  myConvertFuntion x      Where my custom function is   private Type2 myConvertFunction Type1 obj        do something to cast Type1 into Type2    return new Type2

User · Answer

If you know you want to convert from List lt T1 gt  to List lt T2 gt  then List lt T gt  ConvertAll will be slightly more efficient than Select ToList because it knows the exact size to start with   target   orig ConvertAll x   gt  new TargetType   SomeValue   x SomeValue       In the more general case when you only know about the source as an IEnumerable lt T gt   using Select ToList is the way to go  You could also argue that in a world with LINQ  it s more idiomatic to start with    but it s worth at least being aware of the ConvertAll option

User · Answer

var target   origList ConvertAll x   gt   TargetType x

User · Answer

I believe something like this should work   origList Select a   gt  new TargetType     SomeValue   a SomeValue

User · Answer

var list1   new List lt Type1 gt     var list2   new List lt Type2 gt      list1 ForEach item   gt  list2 Add new Type2     Prop1   value1

User · Answer

List lt target gt  targetList   new List lt target gt  originalList Cast lt target gt

User · Answer

Here s a simple example    List lt char gt  c   new List lt char gt       A    B    C      List lt string gt  s   c Select x   gt  x ToString    ToList

User · Answer

Assume that you have multiple properties you want to convert   public class OrigType      public string Prop1A  get set       public string Prop1B  get set      public class TargetType      public string Prop2A  get set       public string Prop2B  get set      var list1   new List lt OrigType gt     var list2   new List lt TargetType gt      list1 ConvertAll x   gt  new OrigType   Prop2A   x Prop1A  Prop2B   x Prop1B

[c#] convert a list of objects from one type to another using lambda expression

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