Linq Expression tree Any() issue

Question

Bonjour J'ai des problèmes avec un arbre d'expression utilisant la méthode d'extension .Any().

Voici mon code:

IQueryable<Book> querableBooks = Books.Values.AsQueryable<Book>(); 

ParameterExpression pe = Expression.Parameter(typeof(Book), "book"); 

MemberExpression props = Expression.Property(pe, "properties"); 

ParameterExpression propList = Expression.Parameter(typeof(List<BookProperty>), "properties"); 

var _test = Expression.Lambda<Func<List<BookProperty>, bool>>(operation, new ParameterExpression[] { propList }); 

var _Any = Expression.Call(typeof(Enumerable), "any", new Type[] { typeof(BookProperty) }, new Expression[] { propList }); 

Expression Lamba = Expression.Lambda(_Any, _props); 

_Test renvoie {propriétés => ((bookProperty.type.key == "lingerie") et (bookProperty.value == "1"))}

retours _any {properties.Any()}

retours Lambda

{book.properties => properties.Any()} La classe livre est comme ceci:

public class Book : IBook 
    { 

     public int id { get; set; } 
//Removed for clarity 
     public List<BookProperty> properties { get; set; } 

    } 

Une classe BookProperty:

public class BookProperty 
    { 
     public BookProperty() 
     { 
      value = "0"; 
     } 
     public int id { get; set; } 
     public int bookId { get; set; } 
     public Book book { get; set; } 
     public int typeId { get; set; } 
     public BookPropertyType type { get; set; } 
     public string value { get; set; } 
    } 

Et classe BookPropertyType:

public class BookPropertyType 
    { 
     public int id { get; set; } 
     public string groupe { get; set; } 
     public string key { get; set; } 
     public string label { get; set; } 
     public int order { get; set; } 
     public string editorType { get; set; } 
     public string unite { get; set; } 
    } 

Je suis proche, mais je ne sais pas comment fusionner correctement tout cela pour avoir un requête comme celle-ci

{book.propertie.Any (bookProperty => bookProperty.type.key == "lingerie") Et (bookProperty.value == "1")}

Merci pour votre aide.

Answer 1

Si je comprends bien, vous êtes à la recherche d'expression comme ceci:

Expression<Func<Book, bool>> bookPredicate = book => book.properties.Any(
    bookProperty => bookProperty.type.key == "lingerie" && bookProperty.value == "1"); 

Vous pouvez construire dynamiquement comme ceci:

var book = Expression.Parameter(typeof(Book), "book"); 
var properties = Expression.PropertyOrField(book, "properties"); 
var bookProperty = Expression.Parameter(typeof(BookProperty), "bookProperty"); 
// bookProperty.type.key == "lingerie" 
var conditionA = Expression.Equal(
    Expression.PropertyOrField(Expression.PropertyOrField(bookProperty, "type"), "key"), 
    Expression.Constant("lingerie") 
); 
// bookProperty.value == "1" 
var conditionB = Expression.Equal(
    Expression.PropertyOrField(bookProperty, "value"), 
    Expression.Constant("1") 
); 
// bookProperty.type.key == "lingerie" && bookProperty.value == "1" 
var condition = Expression.AndAlso(conditionA, conditionB); 
// bookProperty => bookProperty.type.key == "lingerie" && bookProperty.value == "1" 
var predicate = Expression.Lambda<Func<BookProperty, bool>>(condition, bookProperty); 
// book.properties.Any(bookProperty => bookProperty.type.key == "lingerie" && bookProperty.value == "1") 
var anyCall = Expression.Call(
    typeof(Enumerable), "Any", new[] { typeof(BookProperty) }, 
    properties, predicate 
); 
// book => book.properties.Any(...) 
var bookPredicate = Expression.Lambda<Func<Book, bool>>(anyCall, book);