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Example of applying an EF Core global query filter on all entity types that implement an interface
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/* | |
Copyright Phil Haack | |
Licensed under the MIT license - https://github.com/haacked/CodeHaacks/blob/main/LICENSE. | |
*/ | |
using System; | |
using System.Linq; | |
using System.Linq.Expressions; | |
using System.Reflection; | |
using Microsoft.EntityFrameworkCore; | |
using Microsoft.EntityFrameworkCore.Metadata.Builders; | |
using Microsoft.EntityFrameworkCore.Metadata.Internal; | |
using Microsoft.EntityFrameworkCore.Query; | |
public static class ModelBuilderExtensions | |
{ | |
static readonly MethodInfo SetQueryFilterMethod = typeof(ModelBuilderExtensions) | |
.GetMethods(BindingFlags.NonPublic | BindingFlags.Static) | |
.Single(t => t.IsGenericMethod && t.Name == nameof(SetQueryFilter)); | |
public static void SetQueryFilterOnAllEntities<TEntityInterface>( | |
this ModelBuilder builder, | |
Expression<Func<TEntityInterface, bool>> filterExpression) | |
{ | |
foreach (var type in builder.Model.GetEntityTypes() | |
.Where(t => t.BaseType == null) | |
.Select(t => t.ClrType) | |
.Where(t => typeof(TEntityInterface).IsAssignableFrom(t))) | |
{ | |
builder.SetEntityQueryFilter( | |
type, | |
filterExpression); | |
} | |
} | |
static void SetEntityQueryFilter<TEntityInterface>( | |
this ModelBuilder builder, | |
Type entityType, | |
Expression<Func<TEntityInterface, bool>> filterExpression) | |
{ | |
SetQueryFilterMethod | |
.MakeGenericMethod(entityType, typeof(TEntityInterface)) | |
.Invoke(null, new object[] { builder, filterExpression }); | |
} | |
static void SetQueryFilter<TEntity, TEntityInterface>( | |
this ModelBuilder builder, | |
Expression<Func<TEntityInterface, bool>> filterExpression) | |
where TEntityInterface : class | |
where TEntity : class, TEntityInterface | |
{ | |
var concreteExpression = filterExpression | |
.Convert<TEntityInterface, TEntity>(); | |
builder.Entity<TEntity>() | |
.AppendQueryFilter(concreteExpression); | |
} | |
// CREDIT: This comment by magiak on GitHub https://github.com/dotnet/efcore/issues/10275#issuecomment-785916356 | |
static void AppendQueryFilter<T>(this EntityTypeBuilder entityTypeBuilder, Expression<Func<T, bool>> expression) | |
where T : class | |
{ | |
var parameterType = Expression.Parameter(entityTypeBuilder.Metadata.ClrType); | |
var expressionFilter = ReplacingExpressionVisitor.Replace( | |
expression.Parameters.Single(), parameterType, expression.Body); | |
if (entityTypeBuilder.Metadata.GetQueryFilter() != null) | |
{ | |
var currentQueryFilter = entityTypeBuilder.Metadata.GetQueryFilter(); | |
var currentExpressionFilter = ReplacingExpressionVisitor.Replace( | |
currentQueryFilter.Parameters.Single(), parameterType, currentQueryFilter.Body); | |
expressionFilter = Expression.AndAlso(currentExpressionFilter, expressionFilter); | |
} | |
var lambdaExpression = Expression.Lambda(expressionFilter, parameterType); | |
entityTypeBuilder.HasQueryFilter(lambdaExpression); | |
} | |
} | |
public static class ExpressionExtensions | |
{ | |
// This magic is courtesy of this StackOverflow post. | |
// https://stackoverflow.com/questions/38316519/replace-parameter-type-in-lambda-expression | |
// I made some tweaks to adapt it to our needs - @haacked | |
public static Expression<Func<TTarget, bool>> Convert<TSource, TTarget>( | |
this Expression<Func<TSource, bool>> root) | |
{ | |
var visitor = new ParameterTypeVisitor<TSource, TTarget>(); | |
return (Expression<Func<TTarget, bool>>)visitor.Visit(root); | |
} | |
class ParameterTypeVisitor<TSource, TTarget> : ExpressionVisitor | |
{ | |
private ReadOnlyCollection<ParameterExpression> _parameters; | |
protected override Expression VisitParameter(ParameterExpression node) | |
{ | |
return _parameters?.FirstOrDefault(p => p.Name == node.Name) | |
?? (node.Type == typeof(TSource) ? Expression.Parameter(typeof(TTarget), node.Name) : node); | |
} | |
protected override Expression VisitLambda<T>(Expression<T> node) | |
{ | |
_parameters = VisitAndConvert(node.Parameters, "VisitLambda"); | |
return Expression.Lambda(Visit(node.Body), _parameters); | |
} | |
} | |
} |
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@Grauenwolf thank you