Add support for multiple TagWith

src/Ardalis.Specification.EntityFrameworkCore/Evaluators/TagWithEvaluator.cs

@@ -9,9 +9,20 @@ private TagWithEvaluator() { }
 
     public IQueryable<T> GetQuery<T>(IQueryable<T> query, ISpecification<T> specification) where T : class
     {
-        if (specification.QueryTag is not null)
+        if (specification is Specification<T> spec)
         {
-            query = query.TagWith(specification.QueryTag);
+            if (spec.OneOrManyQueryTags.IsEmpty) return query;
+
+            if (spec.OneOrManyQueryTags.HasSingleItem)
+            {
+                query = query.TagWith(spec.OneOrManyQueryTags.Single);
+                return query;
+            }
+        }
+
+        foreach (var tag in specification.QueryTags)
+        {
+            query = query.TagWith(tag);
         }
 
         return query;

src/Ardalis.Specification/Ardalis.Specification.csproj

@@ -23,4 +23,10 @@
     <PackageReference Include="System.Memory" />
   </ItemGroup>
 
+  <ItemGroup>
+    <InternalsVisibleTo Include="Ardalis.Specification.EntityFrameworkCore" />
+    <InternalsVisibleTo Include="Ardalis.Specification.EntityFramework6" />
+    <InternalsVisibleTo Include="Ardalis.Specification.Tests" />
+  </ItemGroup>
+
 </Project>

src/Ardalis.Specification/Builders/Builder_TagWith.cs

@@ -63,7 +63,7 @@ public static ISpecificationBuilder<T> TagWith<T>(
     {
         if (condition)
         {
-            builder.Specification.QueryTag = tag;
+            builder.Specification.AddQueryTag(tag);
         }
 
         return builder;

src/Ardalis.Specification/ISpecification.cs

@@ -1,4 +1,6 @@
-namespace Ardalis.Specification;
+using System.ComponentModel;
+
+namespace Ardalis.Specification;
 
 /// <summary>
 /// Encapsulates query logic for <typeparamref name="T"/>,
@@ -84,9 +86,9 @@ public interface ISpecification<T>
     Func<IEnumerable<T>, IEnumerable<T>>? PostProcessingAction { get; }
 
     /// <summary>
-    /// A query tag to help correlate specification with generated SQL queries captured in logs
+    /// Query tags to help correlate specification with generated SQL queries captured in logs.
     /// </summary>
-    string? QueryTag { get; }
+    IEnumerable<string> QueryTags { get; }
 
     /// <summary>
     /// Return whether or not the results should be cached.

src/Ardalis.Specification/Internals/OneOrMany.cs

@@ -0,0 +1,82 @@
+namespace Ardalis.Specification;
+
+internal struct OneOrMany<T>
+{
+    private object? _value;
+
+    public readonly bool IsEmpty => _value is null;
+    public readonly bool HasSingleItem => _value is T;
+
+    public void Add(T item)
+    {
+        if (_value is null)
+        {
+            _value = item;
+            return;
+        }
+
+        if (_value is List<T> list)
+        {
+            list.Add(item);
+            return;
+        }
+
+        if (_value is T singleValue)
+        {
+            _value = new List<T>(2) { singleValue, item };
+            return;
+        }
+    }
+
+    public readonly T Single
+    {
+        get
+        {
+            if (_value is T singleValue)
+            {
+                return singleValue;
+            }
+
+            throw new InvalidOperationException("The value is not a single item.");
+        }
+    }
+
+    public readonly IEnumerable<T> Values
+    {
+        get
+        {
+            if (_value is null)
+            {
+                return Enumerable.Empty<T>();
+            }
+
+            if (_value is List<T> tags)
+            {
+                return tags;
+            }
+
+            if (_value is T singleValue)
+            {
+                return new[] { singleValue };
+            }
+
+            throw new InvalidOperationException("The value is neither a single item nor a list of items.");
+        }
+    }
+
+    public readonly OneOrMany<T> Clone()
+    {
+        var clone = new OneOrMany<T>();
+
+        if (_value is T singleValue)
+        {
+            clone._value = singleValue;
+        }
+        else if (_value is List<T> list)
+        {
+            clone._value = list.ToList();
+        }
+
+        return clone;
+    }
+}

src/Ardalis.Specification/Specification.cs

@@ -48,6 +48,7 @@ public class Specification<T> : ISpecification<T>
     private List<IncludeExpressionInfo>? _includeExpressions;
     private List<string>? _includeStrings;
     private Dictionary<string, object>? _items;
+    private OneOrMany<string> _queryTags = new();
 
     public ISpecificationBuilder<T> Query => new SpecificationBuilder<T>(this);
     protected virtual IInMemorySpecificationEvaluator Evaluator => InMemorySpecificationEvaluator.Default;
@@ -56,9 +57,6 @@ public class Specification<T> : ISpecification<T>
     /// <inheritdoc/>
     public Func<IEnumerable<T>, IEnumerable<T>>? PostProcessingAction { get; internal set; }
 
-    /// <inheritdoc/>
-    public string? QueryTag { get; internal set; }
-
     /// <inheritdoc/>
     public string? CacheKey { get; internal set; }
 
@@ -121,6 +119,7 @@ internal void Add(SearchExpressionInfo<T> searchExpression)
             _searchExpressions.Insert(index, searchExpression);
         }
     }
+    internal void AddQueryTag(string queryTag) => _queryTags.Add(queryTag);
 
     /// <inheritdoc/>
     public Dictionary<string, object> Items => _items ??= [];
@@ -140,6 +139,11 @@ internal void Add(SearchExpressionInfo<T> searchExpression)
     /// <inheritdoc/>
     public IEnumerable<string> IncludeStrings => _includeStrings ?? Enumerable.Empty<string>();
 
+    /// <inheritdoc/>
+    public IEnumerable<string> QueryTags => _queryTags.Values;
+
+    internal OneOrMany<string> OneOrManyQueryTags => _queryTags;
+
     /// <inheritdoc/>
     public virtual IEnumerable<T> Evaluate(IEnumerable<T> entities)
     {
@@ -157,7 +161,6 @@ public virtual bool IsSatisfiedBy(T entity)
     void ISpecification<T>.CopyTo(Specification<T> otherSpec)
     {
         otherSpec.PostProcessingAction = PostProcessingAction;
-        otherSpec.QueryTag = QueryTag;
         otherSpec.CacheKey = CacheKey;
         otherSpec.Take = Take;
         otherSpec.Skip = Skip;
@@ -196,6 +199,11 @@ void ISpecification<T>.CopyTo(Specification<T> otherSpec)
             otherSpec._searchExpressions = _searchExpressions.ToList();
         }
 
+        if (!_queryTags.IsEmpty)
+        {
+            otherSpec._queryTags = _queryTags.Clone();
+        }
+
         if (_items is not null)
         {
             otherSpec._items = new Dictionary<string, object>(_items);

tests/Ardalis.Specification.EntityFrameworkCore.Tests/Evaluators/TagWithEvaluatorTests.cs

@@ -24,7 +24,7 @@ public void QueriesMatch_GivenTag()
     }
 
     [Fact]
-    public void Applies_GivenTag()
+    public void Applies_GivenSingleTag()
     {
         var tag = "asd";
 
@@ -42,4 +42,55 @@ public void Applies_GivenTag()
 
         actual.Should().Be(expected);
     }
+
+    [Fact]
+    public void Applies_GivenTwoTags()
+    {
+        var tag1 = "asd";
+        var tag2 = "qwe";
+
+        var spec = new Specification<Country>();
+        spec.Query
+            .TagWith(tag1)
+            .TagWith(tag2);
+
+        var actual = _evaluator.GetQuery(DbContext.Countries, spec)
+            .Expression
+            .ToString();
+
+        var expected = DbContext.Countries
+            .TagWith(tag1)
+            .TagWith(tag2)
+            .Expression
+            .ToString();
+
+        actual.Should().Be(expected);
+    }
+
+    [Fact]
+    public void Applies_GivenMultipleTags()
+    {
+        var tag1 = "asd";
+        var tag2 = "qwe";
+        var tag3 = "zxc";
+
+        var spec = new Specification<Country>();
+        spec.Query
+            .TagWith(tag1)
+            .TagWith(tag2)
+            .TagWith(tag3);
+
+        var actual = _evaluator.GetQuery(DbContext.Countries, spec)
+            .Expression
+            .ToString();
+
+        var expected = DbContext.Countries
+            .TagWith(tag1)
+            .TagWith(tag2)
+            .TagWith(tag3)
+            .Expression
+            .ToString();
+
+        actual.Should().Be(expected);
+    }
 }

tests/Ardalis.Specification.Tests/Builders/Builder_TagWith.cs

@@ -10,8 +10,8 @@ public void DoesNothing_GivenNoTag()
         var spec1 = new Specification<Customer>();
         var spec2 = new Specification<Customer, string>();
 
-        spec1.QueryTag.Should().BeNull();
-        spec2.QueryTag.Should().BeNull();
+        spec1.QueryTags.Should().BeSameAs(Enumerable.Empty<string>());
+        spec2.QueryTags.Should().BeSameAs(Enumerable.Empty<string>());
     }
 
     [Fact]
@@ -25,12 +25,12 @@ public void DoesNothing_GivenTagWithFalseCondition()
         spec2.Query
             .TagWith("asd", false);
 
-        spec1.QueryTag.Should().BeNull();
-        spec2.QueryTag.Should().BeNull();
+        spec1.QueryTags.Should().BeSameAs(Enumerable.Empty<string>());
+        spec2.QueryTags.Should().BeSameAs(Enumerable.Empty<string>());
     }
 
     [Fact]
-    public void SetsTag_GivenTag()
+    public void SetsTag_GivenSingleTag()
     {
         var tag = "asd";
 
@@ -42,7 +42,63 @@ public void SetsTag_GivenTag()
         spec2.Query
             .TagWith(tag);
 
-        spec1.QueryTag.Should().Be(tag);
-        spec2.QueryTag.Should().Be(tag);
+        spec1.QueryTags.Should().ContainSingle();
+        spec1.QueryTags.First().Should().Be(tag);
+        spec2.QueryTags.Should().ContainSingle();
+        spec2.QueryTags.First().Should().Be(tag);
+    }
+
+    [Fact]
+    public void SetsTags_GivenTwoTags()
+    {
+        var tag1 = "asd";
+        var tag2 = "qwe";
+
+        var spec1 = new Specification<Customer>();
+        spec1.Query
+            .TagWith(tag1)
+            .TagWith(tag2);
+
+        var spec2 = new Specification<Customer, string>();
+        spec2.Query
+            .TagWith(tag1)
+            .TagWith(tag2);
+
+        spec1.QueryTags.Should().HaveCount(2);
+        spec1.QueryTags.First().Should().Be(tag1);
+        spec1.QueryTags.Skip(1).First().Should().Be(tag2);
+        spec2.QueryTags.Should().HaveCount(2);
+        spec2.QueryTags.First().Should().Be(tag1);
+        spec2.QueryTags.Skip(1).First().Should().Be(tag2);
+    }
+
+    [Fact]
+    public void SetsTags_GivenMultipleTags()
+    {
+        var tag1 = "asd";
+        var tag2 = "qwe";
+        var tag3 = "zxc";
+
+        var spec1 = new Specification<Customer>();
+        spec1.Query
+            .TagWith(tag1)
+            .TagWith(tag2)
+            .TagWith(tag3);
+
+        var spec2 = new Specification<Customer, string>();
+        spec2.Query
+            .TagWith(tag1)
+            .TagWith(tag2)
+            .TagWith(tag3);
+
+        spec1.QueryTags.Should().HaveCount(3);
+        spec1.QueryTags.First().Should().Be(tag1);
+        spec1.QueryTags.Skip(1).First().Should().Be(tag2);
+        spec1.QueryTags.Skip(2).First().Should().Be(tag3);
+
+        spec2.QueryTags.Should().HaveCount(3);
+        spec2.QueryTags.First().Should().Be(tag1);
+        spec2.QueryTags.Skip(1).First().Should().Be(tag2);
+        spec2.QueryTags.Skip(2).First().Should().Be(tag3);
     }
 }