Model selection (#10)

* add model selection

This adds an optional model property to the prompt file, allowing the prompt developer to specify which model it should be executed against

* Add model configuration to documentation

Author: dazfuller

DotPrompt.Tests/PromptFileTests.cs

@@ -22,6 +22,9 @@ public void FromFile_BasicPrompt_ProducesValidPromptFile()
 
         Assert.Equal("basic", promptFile.Name);
 
+        Assert.NotNull(promptFile.Model);
+        Assert.Equal("claude-3-5-sonnet-latest", promptFile.Model);
+        
         Assert.NotNull(promptFile.Config);
         Assert.Equal(OutputFormat.Text, promptFile.Config.OutputFormat);
         Assert.Equal(500, promptFile.Config.MaxTokens);
@@ -196,6 +199,19 @@ public void FromStream_WithInvalidName_ThrowsAnException()
         Assert.Contains("once cleaned results in an empty string", exception.Message);
     }
 
+    [Fact]
+    public void FromStream_WithMissingModelName_IsPersistedAsNullValue()
+    {
+        const string content = "name: missing-model\nmodel: \nprompts:\n  system: System prompt\n  user: User prompt";
+        using var ms = new MemoryStream(Encoding.UTF8.GetBytes(content));
+        ms.Seek(0, SeekOrigin.Begin);
+
+        var promptFile = PromptFile.FromStream("", ms);
+        
+        Assert.Equal("missing-model", promptFile.Name);
+        Assert.Null(promptFile.Model);
+    }
+
     [Fact]
     public void GenerateUserPrompt_UsingDefaults_CorrectlyGeneratesPromptFromTemplate()
     {

DotPrompt.Tests/SamplePrompts/basic.prompt

@@ -1,3 +1,4 @@
+model: claude-3-5-sonnet-latest
 config:
   outputFormat: text
   temperature: 0.9

DotPrompt/PromptFile.cs

@@ -21,6 +21,11 @@ public partial class PromptFile
     /// Gets, sets the name of the prompt
     /// </summary>
     public required string Name { get; set; }
+    
+    /// <summary>
+    /// Gets, sets the name of the model (or deployment) the prompt should be executed using
+    /// </summary>
+    public string? Model { get; set; }
 
     /// <summary>
     /// Gets, sets the configuration to use for the prompt

README.md

@@ -19,6 +19,7 @@ A complete prompt file would look like this.
 
 ```yaml
 name: Example
+model: gpt-4o
 config:
   outputFormat: text
   temperature: 0.9
@@ -52,6 +53,16 @@ The `name` is optional in the configuration, if it's not provided then the name
 
 If you use this property then when the file is loaded the name is converted to lowercase and spaces are replaced with hyphens. So a name of `My cool Prompt` would become `my-cool-prompt`. This is done to make sure the name is easily accessible from the code.
 
+### Model
+
+This is another optional item in the configuration, but it provides information to the user of the prompt file which model (or deployment for Azure Open AI) it should use. As this can be null if not specified this the consumer should make sure to check before usage. For example:
+
+```csharp
+var model = promptFile.Model ?? "my-default";
+```
+
+Using this option though allows the prompt engineer to be very explicit about which model they intended to be used to provide the best results.
+
 ### Config
 
 The `config` section has some top level items which are provided for the client to use in their LLM calls to set options on each call. The `outputFormat` property takes a value of either `text` or `json` depending on how the LLM is intended to respond to the request. If specifying `json` then some LLMs require either the system or user prompt to state that the expected output is JSON as well. If the library does not detect the term `JSON` in the prompt then it will append a small statement to the system prompt requesting for the response to be in JSON format.
@@ -202,7 +213,6 @@ using Azure.AI.OpenAI;
 using DotPrompt;
 
 var openAiClient = new(new Uri("https://endpoint"), new ApiKeyCredential("abc123"));
-var client = openAiClient.GetChatClient("model");
 
 var promptManager = new PromptManager();
 var promptFile = promptManager.GetPromptFile("example");
@@ -216,6 +226,8 @@ var userPrompt = promptFile.GetUserPrompt(new Dictionary<string, object>
     { "style", "used car salesman" }
 });
 
+var client = openAiClient.GetChatClient(promptFile.Model ?? "default-model");
+
 var completion = await client.CompleteChatAsync(
     [
         new SystemChatMessage(systemPrompt),
@@ -239,7 +251,6 @@ using DotPrompt;
 using DotPrompt.Extensions.OpenAi;
 
 var openAiClient = new(new Uri("https://endpoint"), new ApiKeyCredential("abc123"));
-var client = openAiClient.GetChatClient("model");
 
 var promptManager = new PromptManager();
 var promptFile = promptManager.GetPromptFile("example");
@@ -250,6 +261,8 @@ var promptValues = new Dictionary<string, object>
     { "style", "used car salesman" }
 };
 
+var client = openAiClient.GetChatClient(promptFile.Model ?? "default-model");
+
 var completion = await client.CompleteChatAsync(
     promptFile.ToOpenAiChatMessages(promptValues),
     promptFile.ToOpenAiChatCompletionOptions()
@@ -332,6 +345,11 @@ public class PromptEntity : ITableEntity
     /// </summary>
     public ETag ETag { get; set; }
 
+    /// <summary>
+    /// Gets, sets the model to use
+    /// </summary>
+    public string? Model { get; set; }
+    
     /// <summary>
     /// Gets, sets the output format
     /// </summary>
@@ -395,6 +413,7 @@ public class PromptEntity : ITableEntity
         var promptFile = new PromptFile
         {
             Name = RowKey,
+            Model = Model,
             Config = new PromptConfig
             {
                 OutputFormat = Enum.Parse<OutputFormat>(OutputFormat, true),