Expression Trees are an abstract representation of code in a tree structure where each node of the tree represents a programming construct (conditional, assignment, method call, etc.)
Questions tagged [expression-trees]
2090 questions
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Apply Expression Tree Logic Directly on Properties?
It's possible (perhaps even likely) that I'm mixing up terminology here. So let me explain the idea...
Currently I have an Entity Framework 6 code-first kind of approach, with some persistence-ignorant models and some interfaces for IUnitOfWork and…
David
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1 answer
Build Expression tree for LINQ to Entities Where clause
I want to be able to write the following code for a LINQ to Entities query (EF6)
Repo.ContactRelations.WhereActive()
.Select(r => new ContactModel
{
Id = r.Contact.Id,
FirstName…
ozstudent
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1 answer
Expression Tree throws error
In my VS LIGHTSWITCH 2013 portal application I allow the user to create tiles that link to other internal apps. When a new tile is create a Role with the name 'TileTitle + " User"' is created. This way I can show and hide tiles based on a users…
cmaduro
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1 answer
How to build an anonymous object with expression trees
I have a class
public class SomeClass
{
public int num { get; set; }
public string str{ get; set; }
}
I need to construct a lambda expression like: (x => new {new_num= x.num, new_str= x.str})
Properties are listed in some enumerable object…
Serg Tomcat
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1 answer
Linq Expression from Lambda: specify parameter explicitly
I want to embed an expression tree such as
Expression> expr = (o) => o.Value;
into a larger expression tree generated by a parser. However, the parameter o is already defined inside the outer expression tree. In principle I…
LionAM
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0 answers
SqlFunctions.StringConvert in Expression Tree
I'm attempting to write an expression tree which supports dynamic use of StartsWith on number values.
The idea is to use this method to build dynamic where queries, based on a user input, and execeute them against EF 6.
I’ve already written a…
musium
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1 answer
Getting MemberExpression, expecting ConstantExpression
Many problems today! I can't figure this out so I thought I'd throw it out there.
I am writing a fluent interface to build an SQL string (yes I know about LINQ to Entities...it's a long story).
I am checking the type of expression in an if/else…
serlingpa
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Failing to get a strong name from an Expression
It's probably best I explain with an example.
I am writing a fluent interface, which includes a Where method:
public FluentSearch Where(Expression> expression)
which I might call like this:
.Where(j => j.Driver.Chatiness ==…
serlingpa
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Practical Solution for using ExpressionTree in WCF projects
I want to use Expresstion Trees in WCF Projects
public interface IService1
{
[OperationContract(Name = "GetByPredicate")]
List Get(Expression> expression);
[OperationContract]
List Get();
}
but…
Hamed F
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0 answers
Could not find a matching type in ExpressionSerialization.dll
I use ExpressionSerialization library for serializing Expression Tree but get me an error
Could not find a matching type
WCF Service :
public class Person
{
public int ID { get; set; }
public string Name { get; set;…
Hamed F
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1
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1 answer
Get MemberAssignments from Action
I'm trying to build a method that can capture assignments from a strongly-typed statement body. The method call should look something like this:
myObject.Assign(o =>
{
o.SomeProperty = 1;
…
Sören Kuklau
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1 answer
Expression Tree ToString() method generates strange string WHY?
I need string conversion of an Expression Tree so
I create an Expression Tree and use ToString method like this
var exp = ((Expression>) (x => x.OperationID == operationId)).ToString();
but result is strange
x =>…
Hamed F
- 800
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1
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0 answers
Serialize.Linq does not work in WCF proxy layer
I use Serialize.Linq for send and receive Expression> query between Client and Server in WCF Application service because Expression> can not be serialized
all things seems ok BUT
when I add reference this library to wcf proxy layer and…
Hamed F
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1
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1 answer
DLINQ projecting into concrete types with expression trees
I have an expression tree for Purchase class
public static readonly Expression> CurrentPaidSumLambda =
p => (double?)p.Payments
.Where(pa => pa.Status == SystemConstants.PaymentStatus.Paid)
.Sum(pa => pa.Sum);
I wish…
alex440
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2 answers
How can I convert Linq to Entities Query into expression tree?
Say I have the following query how can I get the base Expression Tree?
MyContext.Items.Select(i=>i.Color);
I want to get the expression tree of this so that I can then use the expression tree to dynamically set what property is being selected (So…
user2125348
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