Generate Expressions from Prompts in Visual Studio Designer

• Nov 11, 2025
• 3 minutes to read

Prompt to Expression converts natural language into valid expressions. With the DevExpress AI-powered Assistant, you can connect to Azure OpenAI or OpenAI services and describe the desired logic in plain text.

The system sends the prompt to the configured AI service, which generates a valid expression. The Expression Editor or Filter Editor displays the result immediately. If Prompt to Expression fails to create a valid expression, it displays a message that informs the user that a valid expression was not generated.

DevExpress AI Assistant for Visual Studio

The DevExpress Unified Component Installer installs the AI-powered Assistant for Visual Studio extension.

Configure AI Services

Go to Tools → Options → DevExpress → AI Assistant to open AI Assistant options.

Option	Description
Endpoint URL	The service endpoint used to connect to Azure OpenAI. For OpenAI connections, this option must be empty.
API Key	A personal access key required to authenticate requests to the AI service.
Model Name	The identifier of the AI model (for example, gpt-4o-mini).
Enable Logging	If enabled, the extension records request and response details for diagnostic purposes. Logs are stored in the following folder: C:\Documents and Settings<UserName>\AppData\Local\DevExpress\AI_Assistant_VSIX
Enable Prompt Caching	If enabled, previously used prompts and responses are cached to improve performance and reduce repeated requests.

Warning

Some OpenAI models (for example, GPT-5, o1, and o3 series) do not support the Temperature parameter. To avoid runtime exceptions when targeting these models, set the Temperature to 1. The value is ignored by the service, but this setting prevents validation/compatibility errors.

Configure Prompt to Expression Options

Option	Description
Retry Attempt Count	Specifies the number of additional attempts the AI makes to regenerate an expression if the previous result is invalid.
Prompt Augmentation	Appends additional instructions to each user prompt.
Temperature	Specifies creativity in AI responses. Set 1 for models (for example, GPT-5, o1, and o3 series) that ignore this parameter to avoid compatibility errors.

Generate Expressions from Prompts

Expression Editor

1. Open the Expression Editor, enter a prompt in the Prompt to Expression field, and click Send.

   

2. AI generates the expression and the Expression Editor displays the result.

   

Filter Editor

1. Open the Filter Editor, enter a prompt in the Prompt to Expression field, and click Send.

   

2. AI generates a filter expression and the Filter Editor displays the result.

   

Troubleshooting

Prompt to Expression Input Is Not Displayed in Filter/Expression Editor

Possible Cause

The DevExpress AI-powered Assistant for Visual Studio extension is disabled.

Solution

Open the Extension Manager in Visual Studio (Extensions → Manage Extensions…). Switch to the Installed tab and enable the DevExpress AI-powered Assistant for Visual Studio extension. Restart Visual Studio.

HTTP 400 (Unsupported Value)

Possible Cause

Some OpenAI models (for example, GPT-5, o1, and o3 series) do not support the Temperature parameter.

Solution

Open AI Assistant Options and check Model Name and Temperature settings. If the selected model does not accept the Temperature, set the Temperature to 1 to avoid errors, or switch to a supported model (for example, gpt-4o-mini).

HTTP 404 (Deployment Not Found)

Possible Cause

The specified model deployment does not exist. This may happen if the deployment name is incorrect, if the deployment was recently created and is not yet active, or if it was deleted.

Solution

Open AI Assistant Options and check the Model Name setting.