Test code chat prompts

To design a prompt that works well, test different versions of the prompt and experiment with prompt parameters to determine what results in the optimal response. You can test prompts programmatically with the Codey APIs and in the Google Cloud console with Vertex AI Studio.

Test chat prompts

To test code chat prompts, choose one of the following methods.

REST

To test a code chat prompt by using the Vertex AI API, send a POST request to the publisher model endpoint.

Before using any of the request data, make the following replacements:

  • PROJECT_ID: Your project ID.
  • Messages: Conversation history provided to the model in a structured alternate-author form. Messages appear in chronological order: oldest first, newest last. When the history of messages causes the input to exceed the maximum length, the oldest messages are removed until the entire prompt is within the allowed limit. There must be an odd number of messages (AUTHOR-CONTENT pairs) for the model to generate a response.
    • AUTHOR: The author of the message.
    • CONTENT: The content of the message.
  • TEMPERATURE: The temperature is used for sampling during response generation. Temperature controls the degree of randomness in token selection. Lower temperatures are good for prompts that require a less open-ended or creative response, while higher temperatures can lead to more diverse or creative results. A temperature of 0 means that the highest probability tokens are always selected. In this case, responses for a given prompt are mostly deterministic, but a small amount of variation is still possible.
  • MAX_OUTPUT_TOKENS: Maximum number of tokens that can be generated in the response. A token is approximately four characters. 100 tokens correspond to roughly 60-80 words.

    Specify a lower value for shorter responses and a higher value for potentially longer responses.

  • CANDIDATE_COUNT: The number of response variations to return. The range of valid values is an int between 1 and 4.

HTTP method and URL: 

POST https://us-central1-aiplatform.googleapis.com/v1/projects/PROJECT_ID/locations/us-central1/publishers/google/models/codechat-bison:predict

Request JSON body: 

{
  "instances": [
    { "messages": [
      {
         "author": "AUTHOR",
         "content": "CONTENT"
      }
  ],
  "parameters": {
    "temperature": TEMPERATURE,
    "maxOutputTokens": MAX_OUTPUT_TOKENS,
    "candidateCount": CANDIDATE_COUNT
  }
}

To send your request, choose one of these options:

curl

Save the request body in a file named request.json, and execute the following command: 

curl -X POST \
     -H "Authorization: Bearer $(gcloud auth print-access-token)" \
     -H "Content-Type: application/json; charset=utf-8" \
     -d @request.json \
     "https://us-central1-aiplatform.googleapis.com/v1/projects/PROJECT_ID/locations/us-central1/publishers/google/models/codechat-bison:predict"

PowerShell

Save the request body in a file named request.json, and execute the following command: 

$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
    -Method POST `
    -Headers $headers `
    -ContentType: "application/json; charset=utf-8" `
    -InFile request.json `
    -Uri "https://us-central1-aiplatform.googleapis.com/v1/projects/PROJECT_ID/locations/us-central1/publishers/google/models/codechat-bison:predict" | Select-Object -Expand Content

You should receive a JSON response similar to the following.

Python

To learn how to install or update the Vertex AI SDK for Python, see Install the Vertex AI SDK for Python. For more information, see the Python API reference documentation. 

from vertexai.language_models import CodeChatModel


def write_a_function(temperature: float = 0.5) -> object:
    """Example of using Codey for Code Chat Model to write a function."""

    # TODO developer - override these parameters as needed:
    parameters = {
        "temperature": temperature,  # Temperature controls the degree of randomness in token selection.
        "max_output_tokens": 1024,  # Token limit determines the maximum amount of text output.
    }

    code_chat_model = CodeChatModel.from_pretrained("codechat-bison@001")
    chat = code_chat_model.start_chat()

    response = chat.send_message(
        "Please help write a function to calculate the min of two numbers", **parameters
    )
    print(f"Response from Model: {response.text}")

    return response

Node.js

Before trying this sample, follow the Node.js setup instructions in the Vertex AI quickstart using client libraries. For more information, see the Vertex AI Node.js API reference documentation.

To authenticate to Vertex AI, set up Application Default Credentials. For more information, see Set up authentication for a local development environment. 

/**
 * TODO(developer): Uncomment these variables before running the sample.\
 * (Not necessary if passing values as arguments)
 */
// const project = 'YOUR_PROJECT_ID';
// const location = 'YOUR_PROJECT_LOCATION';
const aiplatform = require('@google-cloud/aiplatform');

// Imports the Google Cloud Prediction service client
const {PredictionServiceClient} = aiplatform.v1;

// Import the helper module for converting arbitrary protobuf.Value objects.
const {helpers} = aiplatform;

// Specifies the location of the api endpoint
const clientOptions = {
  apiEndpoint: 'us-central1-aiplatform.googleapis.com',
};
const publisher = 'google';
const model = 'codechat-bison@001';

// Instantiates a client
const predictionServiceClient = new PredictionServiceClient(clientOptions);

async function callPredict() {
  // Configure the parent resource
  const endpoint = `projects/${project}/locations/${location}/publishers/${publisher}/models/${model}`;

  // Learn more about creating prompts to work with a code chat model at:
  // https://cloud.google.com/vertex-ai/docs/generative-ai/code/code-chat-prompts
  const prompt = {
    messages: [
      {
        author: 'user',
        content: 'Hi, how are you?',
      },
      {
        author: 'system',
        content: 'I am doing good. What can I help you in the coding world?',
      },
      {
        author: 'user',
        content:
          'Please help write a function to calculate the min of two numbers',
      },
    ],
  };
  const instanceValue = helpers.toValue(prompt);
  const instances = [instanceValue];

  const parameter = {
    temperature: 0.5,
    maxOutputTokens: 1024,
  };
  const parameters = helpers.toValue(parameter);

  const request = {
    endpoint,
    instances,
    parameters,
  };

  // Predict request
  const [response] = await predictionServiceClient.predict(request);
  console.log('Get code chat response');
  const predictions = response.predictions;
  console.log('\tPredictions :');
  for (const prediction of predictions) {
    console.log(`\t\tPrediction : ${JSON.stringify(prediction)}`);
  }
}

callPredict();

Java

Before trying this sample, follow the Java setup instructions in the Vertex AI quickstart using client libraries. For more information, see the Vertex AI Java API reference documentation.

To authenticate to Vertex AI, set up Application Default Credentials. For more information, see Set up authentication for a local development environment. 


import com.google.cloud.aiplatform.v1.EndpointName;
import com.google.cloud.aiplatform.v1.PredictResponse;
import com.google.cloud.aiplatform.v1.PredictionServiceClient;
import com.google.cloud.aiplatform.v1.PredictionServiceSettings;
import com.google.protobuf.InvalidProtocolBufferException;
import com.google.protobuf.Value;
import com.google.protobuf.util.JsonFormat;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class PredictCodeChatSample {

  public static void main(String[] args) throws IOException {
    // TODO(developer): Replace this variable before running the sample.
    String project = "YOUR_PROJECT_ID";

    // Learn more about creating prompts to work with a code chat model at:
    // https://cloud.google.com/vertex-ai/docs/generative-ai/code/code-chat-prompts
    String instance =
        "{ \"messages\": [\n"
            + "{\n"
            + "  \"author\": \"user\",\n"
            + "  \"content\": \"Hi, how are you?\"\n"
            + "},\n"
            + "{\n"
            + "  \"author\": \"system\",\n"
            + "  \"content\": \"I am doing good. What can I help you in the coding world?\"\n"
            + " },\n"
            + "{\n"
            + "  \"author\": \"user\",\n"
            + "  \"content\":\n"
            + "     \"Please help write a function to calculate the min of two numbers.\"\n"
            + "}\n"
            + "]}";
    String parameters = "{\n" + "  \"temperature\": 0.5,\n" + "  \"maxOutputTokens\": 1024\n" + "}";
    String location = "us-central1";
    String publisher = "google";
    String model = "codechat-bison@001";

    predictCodeChat(instance, parameters, project, location, publisher, model);
  }

  // Use a code chat model to generate a code function
  public static void predictCodeChat(
      String instance,
      String parameters,
      String project,
      String location,
      String publisher,
      String model)
      throws IOException {
    final String endpoint = String.format("%s-aiplatform.googleapis.com:443", location);
    PredictionServiceSettings predictionServiceSettings =
        PredictionServiceSettings.newBuilder().setEndpoint(endpoint).build();

    // Initialize client that will be used to send requests. This client only needs to be created
    // once, and can be reused for multiple requests.
    try (PredictionServiceClient predictionServiceClient =
        PredictionServiceClient.create(predictionServiceSettings)) {
      final EndpointName endpointName =
          EndpointName.ofProjectLocationPublisherModelName(project, location, publisher, model);

      Value instanceValue = stringToValue(instance);
      List<Value> instances = new ArrayList<>();
      instances.add(instanceValue);

      Value parameterValue = stringToValue(parameters);

      PredictResponse predictResponse =
          predictionServiceClient.predict(endpointName, instances, parameterValue);
      System.out.println("Predict Response");
      System.out.println(predictResponse);
    }
  }

  // Convert a Json string to a protobuf.Value
  static Value stringToValue(String value) throws InvalidProtocolBufferException {
    Value.Builder builder = Value.newBuilder();
    JsonFormat.parser().merge(value, builder);
    return builder.build();
  }
}

Console

To test a code chat prompt using Vertex AI Studio in the Google Cloud console, do following :

  1. In the Vertex AI section of the Google Cloud console, go to Vertex AI Studio.

    Go to Vertex AI Studio

  2. Click Get started.
  3. Click Code chat.
  4. In Model, select the model with the name that begins with codechat-bison. A three digit number after codechat-bison indicates the version number of the model. For example, codechat-bison@001 is the name of version one of the code chat model.
  5. Adjust Temperature and Token limit to experiment with how they affect the response. For more information, see Code chat model parameters.
  6. In Enter a prompt to begin a conversation, enter a prompt to start a conversation about code.
  7. Click Continue the conversation to submit the prompt to the chat.
  8. After you receive a response, repeat the previous two steps to continue the conversation.
  9. Click Save if you want to save a prompt.
  10. Click View code to see the Python code or a curl command for your prompt.

Example code chat prompt

MODEL_ID="codechat-bison"
PROJECT_ID=PROJECT_ID

curl \
-X POST \
-H "Authorization: Bearer $(gcloud auth print-access-token)" \
-H "Content-Type: application/json" \
https://us-central1-aiplatform.googleapis.com/v1/projects/${PROJECT_ID}/locations/us-central1/publishers/google/models/${MODEL_ID}:predict -d \
$"{
'instances': [
    {
      'messages': [
        {
          'author': 'user',
          'content': 'Hi, how are you?',
        },
        {
          'author': 'system',
          'content': 'I am doing good. What Can I help you with in the coding world?',
        },
        {
          'author': 'user',
          'content': 'Please help write a function to calculate the min of two numbers',
        }
      ]
    }
  ],
  'parameters': {
    'temperature': 0.2,
    'maxOutputTokens': 1024,
    'candidateCount': 1
  }
}"

To learn more about how to design chat prompts, see Chat prompts.

Stream response from code chat model

To view sample code requests and responses using the REST API, see Examples using the streaming REST API.

To view sample code requests and responses using the Vertex AI SDK for Python, see Examples using Vertex AI SDK for Python for streaming.

What's next