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Merge pull request #48 from ScottLilly/add-uniqueitemsattribute
Add uniqueitemsattribute
2 parents 54afc71 + 8e9ab4a commit 26840cd

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‎CSharpExtender/Attributes/UniqueItemsAttribute.cs‎

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using System;
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using System.Collections;
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using System.ComponentModel.DataAnnotations;
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using System.Linq;
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using System.Reflection;
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namespace CSharpExtender.Attributes;
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[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field, AllowMultiple = false)]
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public class UniqueItemsAttribute : ValidationAttribute
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{
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protected override ValidationResult IsValid(object value, ValidationContext validationContext)
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{
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// If the value is null, let [Required] handle it if needed
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if (value == null)
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{
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return ValidationResult.Success;
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}
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// Ensure the value is a collection.
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// Need to explicitly check for string, as it is enumerable.
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if (value is string || value is not IEnumerable collection)
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{
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return new ValidationResult("The UniqueItemsAttribute must be applied to a collection.");
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}
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var items = collection.Cast<object>().ToList();
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if (items.Count == 0)
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{
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return ValidationResult.Success;
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}
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// Check for duplicates based on type
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for (int i = 0; i < items.Count - 1; i++)
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{
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for (int j = i + 1; j < items.Count; j++)
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{
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if (AreItemsEqual(items[i], items[j]))
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{
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// Use ErrorMessage if provided; otherwise, use default
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string errorMessage = ErrorMessage ??
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$"The list contains duplicate items at indices {i} and {j}.";
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return new ValidationResult(errorMessage);
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}
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}
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}
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return ValidationResult.Success;
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}
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private bool AreItemsEqual(object item1, object item2)
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{
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if (item1 == null && item2 == null)
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{
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return true;
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}
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if (item1 == null || item2 == null)
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{
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return false;
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}
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// Handle simple types (e.g., string, int)
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if (item1.GetType().IsValueType || item1 is string)
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{
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return item1.Equals(item2);
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}
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// Handle complex objects by comparing all properties
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var properties = item1.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance);
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foreach (var prop in properties)
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{
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var value1 = prop.GetValue(item1);
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var value2 = prop.GetValue(item2);
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if (value1 == null && value2 == null)
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{
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continue;
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}
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if (value1 == null || value2 == null)
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{
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return false;
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}
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if (!value1.Equals(value2))
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{
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return false;
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}
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}
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return true;
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}
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}

‎README.md‎

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Extension methods and classes I often find useful for C# development.
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## DataAnnotations
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Attribute classes to validate properties in models.
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- **`UniqueItemsAttribute`**: Check that a collection property does not contain duplicate items.
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## Collections
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### GenericCache

‎Test.CSharpExtender/Attributes/Test_UniqueItemsAttribute.cs‎

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using CSharpExtender.Attributes;
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using System.ComponentModel.DataAnnotations;
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namespace Test.CSharpExtender.Attributes;
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public class UniqueItemsAttributeTests
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{
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private static ValidationContext GetValidationContext(object instance) => new(instance);
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// Test class for complex object validation
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private class TestItem(int id, string name)
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{
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public int Id { get; set; } = id;
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public string Name { get; set; } = name;
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}
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[Fact]
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public void UniqueItemsAttribute_NullList_ReturnsSuccess()
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{
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var model = new { Items = null as List<string> };
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var attribute = new UniqueItemsAttribute();
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var result = attribute.GetValidationResult(model.Items, GetValidationContext(model));
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Assert.Equal(ValidationResult.Success, result);
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}
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[Fact]
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public void UniqueItemsAttribute_EmptyList_ReturnsSuccess()
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{
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var model = new { Items = new List<string>() };
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var attribute = new UniqueItemsAttribute();
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var result = attribute.GetValidationResult(model.Items, GetValidationContext(model));
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Assert.Equal(ValidationResult.Success, result);
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}
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[Fact]
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public void UniqueItemsAttribute_UniqueStrings_ReturnsSuccess()
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{
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var model = new { Items = new List<string> { "apple", "banana", "cherry" } };
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var attribute = new UniqueItemsAttribute();
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var result = attribute.GetValidationResult(model.Items, GetValidationContext(model));
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Assert.Equal(ValidationResult.Success, result);
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}
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[Fact]
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public void UniqueItemsAttribute_DuplicateStrings_DefaultErrorMessage()
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{
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var model = new { Items = new List<string> { "apple", "apple", "cherry" } };
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var attribute = new UniqueItemsAttribute();
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var result = attribute.GetValidationResult(model.Items, GetValidationContext(model));
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Assert.NotEqual(ValidationResult.Success, result);
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Assert.Contains("duplicate items", result.ErrorMessage);
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Assert.Contains("indices 0 and 1", result.ErrorMessage);
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}
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[Fact]
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public void UniqueItemsAttribute_DuplicateStrings_CustomErrorMessage()
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{
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var model = new { Items = new List<string> { "apple", "apple", "cherry" } };
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var attribute = new UniqueItemsAttribute { ErrorMessage = "All items must be unique in the list." };
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var result = attribute.GetValidationResult(model.Items, GetValidationContext(model));
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Assert.NotEqual(ValidationResult.Success, result);
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Assert.Equal("All items must be unique in the list.", result.ErrorMessage);
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}
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[Fact]
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public void UniqueItemsAttribute_UniqueNumbers_ReturnsSuccess()
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{
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var model = new { Items = new List<int> { 1, 2, 3 } };
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var attribute = new UniqueItemsAttribute();
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var result = attribute.GetValidationResult(model.Items, GetValidationContext(model));
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Assert.Equal(ValidationResult.Success, result);
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}
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[Fact]
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public void UniqueItemsAttribute_DuplicateNumbers_DefaultErrorMessage()
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{
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var model = new { Items = new List<int> { 1, 2, 2 } };
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var attribute = new UniqueItemsAttribute();
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var result = attribute.GetValidationResult(model.Items, GetValidationContext(model));
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Assert.NotEqual(ValidationResult.Success, result);
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Assert.Contains("duplicate items", result.ErrorMessage);
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Assert.Contains("indices 1 and 2", result.ErrorMessage);
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}
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[Fact]
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public void UniqueItemsAttribute_DuplicateNumbers_CustomErrorMessage()
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{
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var model = new { Items = new List<int> { 1, 2, 2 } };
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var attribute = new UniqueItemsAttribute { ErrorMessage = "Numbers must be unique." };
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var result = attribute.GetValidationResult(model.Items, GetValidationContext(model));
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Assert.NotEqual(ValidationResult.Success, result);
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Assert.Equal("Numbers must be unique.", result.ErrorMessage);
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}
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[Fact]
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public void UniqueItemsAttribute_UniqueComplexObjects_ReturnsSuccess()
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{
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var model = new
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{
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Items = new List<TestItem>
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{
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new TestItem(1, "apple"),
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new TestItem(2, "banana")
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}
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};
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var attribute = new UniqueItemsAttribute();
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var result = attribute.GetValidationResult(model.Items, GetValidationContext(model));
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Assert.Equal(ValidationResult.Success, result);
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}
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[Fact]
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public void UniqueItemsAttribute_DuplicateComplexObjects_DefaultErrorMessage()
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{
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var model = new
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{
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Items = new List<TestItem>
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{
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new TestItem(1, "apple"),
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new TestItem(1, "apple")
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}
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};
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var attribute = new UniqueItemsAttribute();
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var result = attribute.GetValidationResult(model.Items, GetValidationContext(model));
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Assert.NotEqual(ValidationResult.Success, result);
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Assert.Contains("duplicate items", result.ErrorMessage);
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Assert.Contains("indices 0 and 1", result.ErrorMessage);
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}
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[Fact]
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public void UniqueItemsAttribute_DuplicateComplexObjects_CustomErrorMessage()
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{
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var model = new
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{
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Items = new List<TestItem>
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{
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new TestItem(1, "apple"),
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new TestItem(1, "apple")
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}
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};
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var attribute = new UniqueItemsAttribute { ErrorMessage = "Objects in the list must have unique values." };
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var result = attribute.GetValidationResult(model.Items, GetValidationContext(model));
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Assert.NotEqual(ValidationResult.Success, result);
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Assert.Equal("Objects in the list must have unique values.", result.ErrorMessage);
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}
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[Fact]
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public void UniqueItemsAttribute_SingleString_ReturnsError()
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{
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var model = new { Items = "not a list" };
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var attribute = new UniqueItemsAttribute();
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var result = attribute.GetValidationResult(model.Items, GetValidationContext(model));
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Assert.NotEqual(ValidationResult.Success, result);
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Assert.Contains("must be applied to a collection", result.ErrorMessage);
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}
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[Fact]
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public void UniqueItemsAttribute_NonCollectionNonString_ReturnsError()
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{
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var model = new { Items = 42 }; // An int, not a string or collection
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var attribute = new UniqueItemsAttribute();
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var result = attribute.GetValidationResult(model.Items, GetValidationContext(model));
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Assert.NotEqual(ValidationResult.Success, result);
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Assert.Contains("must be applied to a collection", result.ErrorMessage);
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}
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}

‎Test.CSharpExtender/Test.CSharpExtender.csproj‎

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<Project Sdk="Microsoft.NET.Sdk">
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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<TargetFramework>net8.0</TargetFramework>

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