Improved validation handling.

src/Squidex.Domain.Apps.Entities.MongoDb/Contents/MongoContentRepository.cs

@@ -87,6 +87,8 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Contents
                 throw new ValidationException("This odata operation is not supported.");
             }
 
+            try
+            {
                 var contentItems = Collection.Find(filter).Take(odataQuery).Skip(odataQuery).Sort(odataQuery, schema.SchemaDef).ToListAsync();
                 var contentCount = Collection.Find(filter).CountAsync();
 
@@ -99,6 +101,18 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Contents
 
                 return ResultList.Create<IContentEntity>(contentItems.Result, contentCount.Result);
             }
+            catch (MongoQueryException ex)
+            {
+                if (ex.Message.Contains("17406"))
+                {
+                    throw new DomainException("Result set is too large to be retrieved. Use $top parameter to reduce the number of items.");
+                }
+                else
+                {
+                    throw;
+                }
+            }
+        }
 
         public async Task<IResultList<IContentEntity>> QueryAsync(IAppEntity app, ISchemaEntity schema, Status[] status, HashSet<Guid> ids)
         {

src/Squidex.Infrastructure/ValidationException.cs

@@ -9,11 +9,12 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Runtime.Serialization;
+using System.Text;
 
 namespace Squidex.Infrastructure
 {
     [Serializable]
-    public class ValidationException : Exception
+    public class ValidationException : DomainException
     {
         private static readonly List<ValidationError> FallbackErrors = new List<ValidationError>();
         private readonly IReadOnlyList<ValidationError> errors;
@@ -23,27 +24,29 @@ namespace Squidex.Infrastructure
             get { return errors; }
         }
 
-        public ValidationException(string message, params ValidationError[] errors)
+        public string Summary { get; }
-            : base(message)
+
+        public ValidationException(string summary, params ValidationError[] errors)
+            : this(summary, null, errors?.ToList())
         {
-            this.errors = errors != null ? errors.ToList() : FallbackErrors;
         }
 
-        public ValidationException(string message, IReadOnlyList<ValidationError> errors)
+        public ValidationException(string summary, IReadOnlyList<ValidationError> errors)
-            : base(message)
+            : this(summary, null, errors)
         {
             this.errors = errors ?? FallbackErrors;
         }
 
-        public ValidationException(string message, Exception inner, params ValidationError[] errors)
+        public ValidationException(string summary, Exception inner, params ValidationError[] errors)
-            : base(message, inner)
+            : this(summary, null, errors?.ToList())
         {
-            this.errors = errors != null ? errors.ToList() : FallbackErrors;
         }
 
-        public ValidationException(string message, Exception inner, IReadOnlyList<ValidationError> errors)
+        public ValidationException(string summary, Exception inner, IReadOnlyList<ValidationError> errors)
-            : base(message, inner)
+            : base(FormatMessage(summary, errors), inner)
         {
+            Summary = summary;
+
             this.errors = errors ?? FallbackErrors;
         }
 
@@ -52,9 +55,39 @@ namespace Squidex.Infrastructure
         {
         }
 
-        public override string ToString()
+        private static string FormatMessage(string summary, IReadOnlyList<ValidationError> errors)
+        {
+            var sb = new StringBuilder();
+
+            sb.Append(summary.TrimEnd(' ', '.', ':'));
+
+            if (errors?.Count > 0)
+            {
+                sb.Append(": ");
+
+                for (var i = 0; i < errors.Count; i++)
+                {
+                    var error = errors[i].Message;
+
+                    sb.Append(error);
+
+                    if (!error.EndsWith(".", StringComparison.OrdinalIgnoreCase))
                     {
-            return string.Join(" ", Enumerable.Repeat(Message, 1).Union(Errors.Select(x => x.Message)));
+                        sb.Append(".");
+                    }
+
+                    if (i < errors.Count - 1)
+                    {
+                        sb.Append(" ");
+                    }
+                }
+            }
+            else
+            {
+                sb.Append(".");
+            }
+
+            return sb.ToString();
         }
     }
 }

src/Squidex/Pipeline/ApiExceptionFilterAttribute.cs

@@ -54,7 +54,7 @@ namespace Squidex.Pipeline
 
         private static IActionResult OnValidationException(ValidationException ex)
         {
-            return ErrorResult(400, new ErrorDto { Message = ex.Message, Details = ex.Errors.Select(e => e.Message).ToArray() });
+            return ErrorResult(400, new ErrorDto { Message = ex.Summary, Details = ex.Errors.Select(e => e.Message).ToArray() });
         }
 
         private static IActionResult ErrorResult(int statusCode, ErrorDto error)

tests/Squidex.Infrastructure.Tests/ValidationExceptionTests.cs

@@ -0,0 +1,54 @@
+// ==========================================================================
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex UG (haftungsbeschraenkt)
+//  All rights reserved. Licensed under the MIT license.
+// ==========================================================================
+
+using Xunit;
+
+namespace Squidex.Infrastructure
+{
+    public class ValidationExceptionTests
+    {
+        [Fact]
+        public void Should_format_message_from_summary()
+        {
+            var ex = new ValidationException("Summary.");
+
+            Assert.Equal("Summary.", ex.Message);
+        }
+
+        [Fact]
+        public void Should_append_dot_to_summary()
+        {
+            var ex = new ValidationException("Summary");
+
+            Assert.Equal("Summary.", ex.Message);
+        }
+
+        [Fact]
+        public void Should_format_message_from_errors()
+        {
+            var ex = new ValidationException("Summary", new ValidationError("Error1."), new ValidationError("Error2."));
+
+            Assert.Equal("Summary: Error1. Error2.", ex.Message);
+        }
+
+        [Fact]
+        public void Should_not_add_colon_twice()
+        {
+            var ex = new ValidationException("Summary:", new ValidationError("Error1."), new ValidationError("Error2."));
+
+            Assert.Equal("Summary: Error1. Error2.", ex.Message);
+        }
+
+        [Fact]
+        public void Should_append_dots_to_errors()
+        {
+            var ex = new ValidationException("Summary", new ValidationError("Error1"), new ValidationError("Error2"));
+
+            Assert.Equal("Summary: Error1. Error2.", ex.Message);
+        }
+    }
+}