Simplify setting manager by extracting two default contributor.

src/Volo.Abp.Settings/Volo/Abp/Settings/DefaultStoreSettingContributor.cs

@@ -0,0 +1,19 @@
+using System.Threading.Tasks;
+
+namespace Volo.Abp.Settings
+{
+    public class DefaultStoreSettingContributor : SettingContributor
+    {
+        public override string EntityType => null;
+
+        public DefaultStoreSettingContributor(ISettingStore settingStore) 
+            : base(settingStore)
+        {
+        }
+
+        public override Task<string> GetOrNullAsync(SettingDefinition setting, string entityId)
+        {
+            return SettingStore.GetOrNullAsync(setting.Name, null, null);
+        }
+    }
+}

src/Volo.Abp.Settings/Volo/Abp/Settings/DefaultValueSettingContributor.cs

@@ -0,0 +1,20 @@
+using System.Threading.Tasks;
+
+namespace Volo.Abp.Settings
+{
+    public class DefaultValueSettingContributor : SettingContributor
+    {
+        public override string EntityType => null;
+
+        public DefaultValueSettingContributor(ISettingStore settingStore) 
+            : base(settingStore)
+        {
+
+        }
+
+        public override Task<string> GetOrNullAsync(SettingDefinition setting, string entityId)
+        {
+            return Task.FromResult(setting.DefaultValue);
+        }
+    }
+}

src/Volo.Abp.Settings/Volo/Abp/Settings/SettingManager.cs

@@ -43,7 +43,9 @@ namespace Volo.Abp.Settings
 
             var setting = SettingDefinitionManager.Get(name);
 
-            foreach (var contributor in Enumerable.Reverse(Contributors.Value))
+            var contributors = Enumerable.Reverse(Contributors.Value);
+
+            foreach (var contributor in contributors)
             {
                 var value = await contributor.GetOrNullAsync(setting, null);
                 if (value != null)
@@ -52,13 +54,7 @@ namespace Volo.Abp.Settings
                 }
             }
 
-            var defaultStoreValue = await SettingStore.GetOrNullAsync(name, null, null);
-            if (defaultStoreValue != null)
-            {
-                return defaultStoreValue;
-            }
-
-            return setting.DefaultValue;
+            return null;
         }
 
         public virtual async Task<string> GetOrNullAsync(string name, string entityType, string entityId, bool fallback = true)
@@ -68,27 +64,25 @@ namespace Volo.Abp.Settings
 
             var setting = SettingDefinitionManager.Get(name);
 
-            foreach (var contributor in GetFilteredContributors(entityType, fallback))
-            {
-                var value = await contributor.GetOrNullAsync(setting, entityId);
-                if (value != null)
-                {
-                    return value;
-                }
-            }
+            var contributors = Enumerable
+                .Reverse(Contributors.Value)
+                .SkipWhile(c => c.EntityType != entityType);
 
             if (!fallback)
             {
-                return null;
+                contributors = contributors.TakeWhile(c => c.EntityType == entityType);
             }
 
-            var defaultStoreValue = await SettingStore.GetOrNullAsync(name, null, null);
-            if (defaultStoreValue != null)
+            foreach (var contributor in contributors)
             {
-                return defaultStoreValue;
+                var value = await contributor.GetOrNullAsync(setting, entityId);
+                if (value != null)
+                {
+                    return value;
+                }
             }
 
-            return setting.DefaultValue;
+            return null;
         }
 
         public Task<List<SettingValue>> GetAllAsync()
@@ -110,19 +104,5 @@ namespace Volo.Abp.Settings
         {
             throw new System.NotImplementedException();
         }
-
-        private IEnumerable<ISettingContributor> GetFilteredContributors(string entityType, bool fallback)
-        {
-            var contributors = Enumerable
-                .Reverse(Contributors.Value)
-                .SkipWhile(c => c.EntityType != entityType);
-
-            if (!fallback)
-            {
-                contributors = contributors.TakeWhile(c => c.EntityType == entityType);
-            }
-
-            return contributors;
-        }
     }
 }

src/Volo.Abp.Settings/Volo/Abp/Settings/SettingOptions.cs

@@ -4,14 +4,18 @@ namespace Volo.Abp.Settings
 {
     public class SettingOptions
     {
-        public ITypeList<ISettingContributor> Contributors { get; }
-
         public ITypeList<ISettingProvider> Providers { get; set; }
 
+        public ITypeList<ISettingContributor> Contributors { get; }
+
         public SettingOptions()
         {
-            Contributors = new TypeList<ISettingContributor>();
             Providers = new TypeList<ISettingProvider>();
+            Contributors = new TypeList<ISettingContributor>
+            {
+                typeof(DefaultValueSettingContributor),
+                typeof(DefaultStoreSettingContributor)
+            };
         }
     }
 }