ValueComparer<T> Class
Definition
Important
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Specifies custom value snapshotting and comparison for CLR types that cannot be compared with Equals(Object, Object) and/or need a deep copy when taking a snapshot. For example, arrays of primitive types will require both if mutation is to be detected.
public class ValueComparer<T> : Microsoft.EntityFrameworkCore.ChangeTracking.ValueComparer, System.Collections.Generic.IEqualityComparer<T>type ValueComparer<'T> = class
inherit ValueComparer
interface IEqualityComparer<'T>Public Class ValueComparer(Of T)
Inherits ValueComparer
Implements IEqualityComparer(Of T)Type Parameters
- T
The type.
- Inheritance
- Derived
- Implements
Remarks
Snapshotting is the process of creating a copy of the value into a snapshot so it can later be compared to determine if it has changed. For some types, such as collections, this needs to be a deep copy of the collection rather than just a shallow copy of the reference.
See EF Core value comparers for more information and examples.
Constructors
| ValueComparer<T>(Boolean) |
Creates a new ValueComparer<T> with a default comparison expression and a shallow copy for the snapshot. |
| ValueComparer<T>(Expression<Func<T,T,Boolean>>, Expression<Func<T,Int32>>, Expression<Func<T,T>>) |
Creates a new ValueComparer<T> with the given comparison and snapshotting expressions. |
| ValueComparer<T>(Expression<Func<T,T,Boolean>>, Expression<Func<T,Int32>>) |
Creates a new ValueComparer<T> with the given comparison expression. A shallow copy will be used for the snapshot. |
Properties
| ConstructorExpression |
The expression representing construction of this object. |
| ConstructorExpression |
The expression representing construction of this object. (Inherited from ValueComparer) |
| EqualsExpression |
The comparison expression. |
| HashCodeExpression |
The hash code expression. |
| ObjectEqualsExpression |
The object comparison expression. |
| ObjectEqualsExpression |
The object comparison expression. (Inherited from ValueComparer) |
| SnapshotExpression |
The snapshot expression. |
| Type |
The type. |
Methods
| CreateDefaultEqualsExpression() |
Creates an expression for equality. |
| CreateDefaultHashCodeExpression(Boolean) |
Creates an expression for generating a hash code. |
| CreateDefaultSnapshotExpression(Boolean) |
Creates an expression for creating a snapshot of a value. |
| Equals(Object, Object) |
Compares the two instances to determine if they are equal. |
| Equals(T, T) |
Compares the two instances to determine if they are equal. |
| ExtractEqualsBody(Expression, Expression) |
Takes EqualsExpression and replaces the two parameters with the given expressions, returning the transformed body. (Inherited from ValueComparer) |
| ExtractHashCodeBody(Expression) |
Takes the HashCodeExpression and replaces the parameter with the given expression, returning the transformed body. (Inherited from ValueComparer) |
| ExtractSnapshotBody(Expression) |
Takes the SnapshotExpression and replaces the parameter with the given expression, returning the transformed body. (Inherited from ValueComparer) |
| GetHashCode(Object) |
Returns the hash code for the given instance. |
| GetHashCode(T) |
Returns the hash code for the given instance. |
| Snapshot(Object) |
Creates a snapshot of the given instance. |
| Snapshot(T) |
Creates a snapshot of the given instance. |
Extension Methods
| IsDefault(ValueComparer) |
Returns |
