Avoid multiple enumeration in MultiLingualObjectManager

framework/src/Volo.Abp.MultiLingualObjects/Volo/Abp/MultiLingualObjects/MultiLingualObjectManager.cs

@@ -28,12 +28,13 @@ public class MultiLingualObjectManager : IMultiLingualObjectManager, ITransientD
     {
         culture ??= CultureInfo.CurrentUICulture.Name;
 
-        if (translations == null || !translations.Any())
+        var translationList = translations?.ToList();
+        if (translationList == null || translationList.Count == 0)
         {
             return null;
         }
 
-        var translation = translations.FirstOrDefault(pt => pt.Language == culture);
+        var translation = translationList.FirstOrDefault(pt => pt.Language == culture);
         if (translation != null)
         {
             return translation;
@@ -43,7 +44,7 @@ public class MultiLingualObjectManager : IMultiLingualObjectManager, ITransientD
         {
             translation = GetTranslationBasedOnCulturalRecursive(
                 CultureInfo.CurrentUICulture.Parent,
-                translations,
+                translationList,
                 0
             );
 
@@ -55,13 +56,13 @@ public class MultiLingualObjectManager : IMultiLingualObjectManager, ITransientD
 
         var defaultLanguage = await SettingProvider.GetOrNullAsync(LocalizationSettingNames.DefaultLanguage);
 
-        translation = translations.FirstOrDefault(pt => pt.Language == defaultLanguage);
+        translation = translationList.FirstOrDefault(pt => pt.Language == defaultLanguage);
         if (translation != null)
         {
             return translation;
         }
 
-        translation = translations.FirstOrDefault();
+        translation = translationList.FirstOrDefault();
         return translation;
     }
 
@@ -96,16 +97,17 @@ public class MultiLingualObjectManager : IMultiLingualObjectManager, ITransientD
     {
         culture ??= CultureInfo.CurrentUICulture.Name;
 
-        if (translationsCombined == null || !translationsCombined.Any())
+        var translationsCombinedList = translationsCombined?.Select(translations => translations.ToList()).ToList();
+        if (translationsCombinedList == null || translationsCombinedList.Count == 0)
         {
             return new();
         }
 
         var someHaveNoTranslations = false;
         var res = new List<TTranslation?>();
-        foreach (var translations in translationsCombined)
+        foreach (var translations in translationsCombinedList)
         {
-            if (!translations.Any())
+            if (translations.Count == 0)
             {
                 //if the src has no translations, don't try to find a translation
                 res.Add(null);
@@ -150,10 +152,10 @@ public class MultiLingualObjectManager : IMultiLingualObjectManager, ITransientD
             var defaultLanguage = await SettingProvider.GetOrNullAsync(LocalizationSettingNames.DefaultLanguage);
 
             var index = 0;
-            foreach (var translations in translationsCombined)
+            foreach (var translations in translationsCombinedList)
             {
                 //if the src has no translations, don't try to find a translation
-                if (translations.Any() && res[index] == null)
+                if (translations.Count > 0 && res[index] == null)
                 {
                     res[index] = translations.FirstOrDefault(pt => pt.Language == defaultLanguage) ??
                                  translations.FirstOrDefault();
@@ -168,10 +170,11 @@ public class MultiLingualObjectManager : IMultiLingualObjectManager, ITransientD
        where TMultiLingual : IMultiLingualObject<TTranslation>
        where TTranslation : class, IObjectTranslation
     {
-        var resInitial = await GetBulkTranslationsAsync(multiLinguals.Select(x => x.Translations), culture, fallbackToParentCultures);
+        var multiLingualList = multiLinguals.ToList();
+        var resInitial = await GetBulkTranslationsAsync(multiLingualList.Select(x => x.Translations), culture, fallbackToParentCultures);
         var index = 0;
         var res = new List<(TMultiLingual entity, TTranslation? translation)>();
-        foreach (var item in multiLinguals)
+        foreach (var item in multiLingualList)
         {
             var t = resInitial[index++];
             res.Add((item, t));

framework/test/Volo.Abp.MultiLingualObjects.Tests/Volo/Abp/MultiLingualObjects/MultiLingualObjectManager_Tests.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections;
 using System.Collections.Frozen;
 using System.Collections.Generic;
 using System.Linq;
@@ -188,6 +189,68 @@ public class MultiLingualObjectManager_Tests : AbpIntegratedTest<AbpMultiLingual
         }
     }
 
+    [Fact]
+    public async Task GetTranslationAsync_Should_Enumerate_Translations_Once()
+    {
+        using (CultureHelper.Use("en-us"))
+        {
+            var translation = await _multiLingualObjectManager.GetTranslationAsync(
+                new OneTimeEnumerable<MultiLingualBookTranslation>(_book.Translations));
+
+            translation.ShouldNotBeNull();
+            translation.Name.ShouldBe(_testTranslations["en"]);
+        }
+    }
+
+    [Fact]
+    public async Task GetBulkTranslationsAsync_Should_Enumerate_Entities_Once()
+    {
+        using (CultureHelper.Use("fr-FR"))
+        {
+            var books = new List<MultiLingualBook>
+            {
+                //resolved by the fallback pass
+                GetTestBook("ar", "en"),
+                //has no translations
+                GetTestBook(),
+                //resolved by the first-translation fallback
+                GetTestBook("ar")
+            };
+
+            var translations = await _multiLingualObjectManager.GetBulkTranslationsAsync<MultiLingualBook, MultiLingualBookTranslation>(
+                new OneTimeEnumerable<MultiLingualBook>(books));
+
+            translations.Count.ShouldBe(3);
+            translations[0].entity.ShouldBe(books[0]);
+            translations[0].translation!.Name.ShouldBe(_testTranslations["en"]);
+            translations[1].entity.ShouldBe(books[1]);
+            translations[1].translation.ShouldBeNull();
+            translations[2].entity.ShouldBe(books[2]);
+            translations[2].translation!.Name.ShouldBe(_testTranslations["ar"]);
+        }
+    }
+
+    [Fact]
+    public async Task GetBulkTranslationsAsync_Should_Enumerate_Translation_Sequences_Once()
+    {
+        using (CultureHelper.Use("fr-FR"))
+        {
+            var translationsCombined = new OneTimeEnumerable<IEnumerable<MultiLingualBookTranslation>>(
+                _books
+                    .Select(x => (IEnumerable<MultiLingualBookTranslation>)new OneTimeEnumerable<MultiLingualBookTranslation>(x.Translations))
+                    .ToList());
+
+            var translations = await _multiLingualObjectManager.GetBulkTranslationsAsync(translationsCombined);
+
+            translations.Count.ShouldBe(_books.Count);
+            translations[0].ShouldBeNull();
+            translations[1]!.Name.ShouldBe(_testTranslations["en"]);
+            translations[2]!.Name.ShouldBe(_testTranslations["ar"]);
+            translations[3]!.Name.ShouldBe(_testTranslations["en"]);
+            translations[4]!.Name.ShouldBe(_testTranslations["en"]);
+        }
+    }
+
     [Fact]
     public async Task TestBulkMapping()
     {
@@ -210,4 +273,31 @@ public class MultiLingualObjectManager_Tests : AbpIntegratedTest<AbpMultiLingual
             }
         }
     }
+
+    private class OneTimeEnumerable<T> : IEnumerable<T>
+    {
+        private readonly IEnumerable<T> _source;
+        private bool _enumerated;
+
+        public OneTimeEnumerable(IEnumerable<T> source)
+        {
+            _source = source;
+        }
+
+        public IEnumerator<T> GetEnumerator()
+        {
+            if (_enumerated)
+            {
+                throw new InvalidOperationException("The sequence was enumerated more than once");
+            }
+
+            _enumerated = true;
+            return _source.GetEnumerator();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
+    }
 }