Adds optional function to get the display string for TextPrompt choices

src/Spectre.Console.Tests/Expectations/PromptTests.Should_Use_Custom_Converter.verified.txt

@@ -0,0 +1 @@
+Favorite fruit? [Apple/Banana]: Banana

src/Spectre.Console.Tests/Unit/PromptTests.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Threading.Tasks;
+using Shouldly;
 using VerifyXunit;
 using Xunit;
 
@@ -168,5 +169,24 @@ namespace Spectre.Console.Tests.Unit
             // Then
             return Verifier.Verify(console.Output);
         }
+
+        [Fact]
+        public Task Should_Use_Custom_Converter()
+        {
+            // Given
+            var console = new PlainConsole();
+            console.Input.PushTextWithEnter("Banana");
+
+            // When
+            var result = console.Prompt(
+                new TextPrompt<(int, string)>("Favorite fruit?")
+                    .AddChoice((1, "Apple"))
+                    .AddChoice((2, "Banana"))
+                    .WithConverter(testData => testData.Item2));
+
+            // Then
+            result.Item1.ShouldBe(2);
+            return Verifier.Verify(console.Output);
+        }
     }
 }

src/Spectre.Console/Widgets/Prompt/TextPrompt.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Linq;
@@ -15,6 +16,7 @@ namespace Spectre.Console
     public sealed class TextPrompt<T> : IPrompt<T>
     {
         private readonly string _prompt;
+        private readonly StringComparer? _comparer;
 
         /// <summary>
         /// Gets or sets the prompt style.
@@ -24,7 +26,7 @@ namespace Spectre.Console
         /// <summary>
         /// Gets the list of choices.
         /// </summary>
-        public HashSet<T> Choices { get; }
+        public List<T> Choices { get; } = new List<T>();
 
         /// <summary>
         /// Gets or sets the message for invalid choices.
@@ -59,6 +61,12 @@ namespace Spectre.Console
         /// </summary>
         public bool AllowEmpty { get; set; }
 
+        /// <summary>
+        /// Gets or sets the converter to get the display string for a choice. By default
+        /// the corresponding <see cref="TypeConverter"/> is used.
+        /// </summary>
+        public Func<T, string>? Converter { get; set; } = TypeConverterHelper.ConvertToString;
+
         /// <summary>
         /// Gets or sets the validator.
         /// </summary>
@@ -74,11 +82,10 @@ namespace Spectre.Console
         /// </summary>
         /// <param name="prompt">The prompt markup text.</param>
         /// <param name="comparer">The comparer used for choices.</param>
-        public TextPrompt(string prompt, IEqualityComparer<T>? comparer = null)
+        public TextPrompt(string prompt, StringComparer? comparer = null)
         {
             _prompt = prompt;
-
-            Choices = new HashSet<T>(comparer ?? EqualityComparer<T>.Default);
+            _comparer = comparer;
         }
 
         /// <summary>
@@ -95,7 +102,9 @@ namespace Spectre.Console
             }
 
             var promptStyle = PromptStyle ?? Style.Plain;
-            var choices = Choices.Select(choice => TypeConverterHelper.ConvertToString(choice));
+            var converter = Converter ?? TypeConverterHelper.ConvertToString;
+            var choices = Choices.Select(choice => converter(choice)).ToList();
+            var choiceMap = Choices.ToDictionary(choice => converter(choice), choice => choice, _comparer);
 
             WritePrompt(console);
 
@@ -108,7 +117,7 @@ namespace Spectre.Console
                 {
                     if (DefaultValue != null)
                     {
-                        console.Write(TypeConverterHelper.ConvertToString(DefaultValue.Value), promptStyle);
+                        console.Write(converter(DefaultValue.Value), promptStyle);
                         console.WriteLine();
                         return DefaultValue.Value;
                     }
@@ -121,17 +130,10 @@ namespace Spectre.Console
 
                 console.WriteLine();
 
-                // Try convert the value to the expected type.
-                if (!TypeConverterHelper.TryConvertFromString<T>(input, out var result) || result == null)
-                {
-                    console.MarkupLine(ValidationErrorMessage);
-                    WritePrompt(console);
-                    continue;
-                }
-
+                T? result;
                 if (Choices.Count > 0)
                 {
-                    if (Choices.Contains(result))
+                    if (choiceMap.TryGetValue(input, out result) && result != null)
                     {
                         return result;
                     }
@@ -142,6 +144,12 @@ namespace Spectre.Console
                         continue;
                     }
                 }
+                else if (!TypeConverterHelper.TryConvertFromString<T>(input, out result) || result == null)
+                {
+                    console.MarkupLine(ValidationErrorMessage);
+                    WritePrompt(console);
+                    continue;
+                }
 
                 // Run all validators
                 if (!ValidateResult(result, out var validationMessage))
@@ -171,7 +179,8 @@ namespace Spectre.Console
 
             if (ShowChoices && Choices.Count > 0)
             {
-                var choices = string.Join("/", Choices.Select(choice => TypeConverterHelper.ConvertToString(choice)));
+                var converter = Converter ?? TypeConverterHelper.ConvertToString;
+                var choices = string.Join("/", Choices.Select(choice => converter(choice)));
                 builder.AppendFormat(CultureInfo.InvariantCulture, " [blue][[{0}]][/]", choices);
             }
 

src/Spectre.Console/Widgets/Prompt/TextPromptExtensions.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 
 namespace Spectre.Console
 {
@@ -246,6 +247,33 @@ namespace Spectre.Console
             return obj;
         }
 
+        /// <summary>
+        /// Adds multiple choices to the prompt.
+        /// </summary>
+        /// <typeparam name="T">The prompt result type.</typeparam>
+        /// <param name="obj">The prompt.</param>
+        /// <param name="choices">The choices to add.</param>
+        /// <returns>The same instance so that multiple calls can be chained.</returns>
+        public static TextPrompt<T> AddChoices<T>(this TextPrompt<T> obj, IEnumerable<T> choices)
+        {
+            if (obj is null)
+            {
+                throw new ArgumentNullException(nameof(obj));
+            }
+
+            if (choices is null)
+            {
+                throw new ArgumentNullException(nameof(choices));
+            }
+
+            foreach (var choice in choices)
+            {
+                obj.Choices.Add(choice);
+            }
+
+            return obj;
+        }
+
         /// <summary>
         /// Replaces prompt user input with asterixes in the console.
         /// </summary>
@@ -262,5 +290,23 @@ namespace Spectre.Console
             obj.IsSecret = true;
             return obj;
         }
+
+        /// <summary>
+        /// Sets the function to create a display string for a given choice.
+        /// </summary>
+        /// <typeparam name="T">The prompt type.</typeparam>
+        /// <param name="obj">The prompt.</param>
+        /// <param name="displaySelector">The function to get a display string for a given choice.</param>
+        /// <returns>The same instance so that multiple calls can be chained.</returns>
+        public static TextPrompt<T> WithConverter<T>(this TextPrompt<T> obj, Func<T, string>? displaySelector)
+        {
+            if (obj is null)
+            {
+                throw new ArgumentNullException(nameof(obj));
+            }
+
+            obj.Converter = displaySelector;
+            return obj;
+        }
     }
 }