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Shrijith Venkatramana
Shrijith Venkatramana

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Manage TOML Configuration From VSCode Extension - DBChat Part 8

Hi there! I'm Shrijith Venkatrama, the founder of Hexmos. Right now, I’m building LiveAPI, a super-convenient tool that simplifies engineering workflows by generating awesome API docs from your code in minutes.

In this tutorial series, I am on a journey to build for myself DBChat - a simple tool for using AI chat to explore and evolve databases.

See previous posts to get more context:

  1. Building DBChat - Explore and Evolve Your DB with Simple Chat (Part 1)
  2. DBChat: Getting a Toy REPL Going in Golang (Part 2)
  3. DBChat Part 3 - Configure , Connect & Dump Databases
  4. Chat With Your DB via DBChat & Gemini (Part 4)
  5. The Language Server Protocol - Building DBChat (Part 5)
  6. Making DBChat VSCode Extension - Ping Pong With LSP Backend (Part 6)
  7. Starting a VSCode Extension UI For DBChat (Part 7)

Building a TOML Connections Manager UI for DBChat in VSCode Extension

In the previous post - we had the skeletons of a simple chat UI and database connections form in DBChat VSCode extension.

In this post, I will demonstrate how DBChat extension can manipulate the ~/.dbchat.toml config file's [connections] section to add/update/delete entries.

To jog your memory, the config file is supposed to have a structure like this:

# DBChat Sample Configuration File
# Copy this file to ~/.dbchat.toml and modify as needed

[connections]
# Format: name = "connection_string"
local = "postgresql://postgres:postgres@localhost:5432/postgres"
liveapi = "postgresql://user:pwd@ip:5432/db_name" 

[llm]
gemini_key = "the_key"
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The Results

DBChat Connections List:

Connections List

DBChat Add/Edit Connection:

Add & Edit Connection

For both Edit and Update - we also have a confirmation prompt to avoid mistakes.

Handling Create Connection Request

The first task is to get the toml extension as follows:

 npm install @iarna/toml
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We get a few new imports:

import * as fs from 'fs/promises';
import * as path from 'path';
import * as os from 'os';
import * as TOML from '@iarna/toml';
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The key structure is a message handler - which will receive events for all the 3 actions:

        const messageHandler = this._view.webview.onDidReceiveMessage(
            async (message) => {
                console.log('Received message:', message);
                switch (message.command) {
                    case 'saveConnection':
                        console.log('Processing saveConnection command');
                        const success = await this._saveConnection(message.name, message.connectionString);
                        if (success) {
                            console.log('Connection saved successfully, closing form');
                            this._showingConnectionForm = false;
                            this._updateView();
                        } else {
                            console.log('Connection not saved, keeping form open');
                        }
                        break;
                    case 'cancel':
                        console.log('Processing cancel command');
                        this._showingConnectionForm = false;
                        this._updateView();
                        break;
                    case 'editConnection':
                        this._showingConnectionForm = true;
                        this._editingConnection = message.name;
                        // First update the view to show the form
                        await this._updateView();
                        // Then send the prefill message after a short delay to ensure the form exists
                        setTimeout(() => {
                            this._view.webview.postMessage({ 
                                command: 'prefillForm', 
                                name: message.name, 
                                connectionString: message.connectionString 
                            });
                        }, 100);
                        break;
                    case 'deleteConnection':
                        const choice = await vscode.window.showWarningMessage(
                            `Are you sure you want to delete connection "${message.name}"?`,
                            'Yes',
                            'No'
                        );
                        if (choice === 'Yes') {
                            const deleted = await this._deleteConnection(message.name);
                            if (deleted) {
                                await this._updateView();  // Update view after successful deletion
                                vscode.window.showInformationMessage(`Connection "${message.name}" deleted successfully.`);
                            }
                        }
                        break;
                }
            }
        );

        // Add message handler to subscriptions for cleanup
        context.subscriptions.push(messageHandler);
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Save Connection is quite simple:

    private async _saveConnection(name: string, connectionString: string): Promise<boolean> {
        console.log('Starting _saveConnection with:', { name, connectionString });
        try {
            const configPath = path.join(os.homedir(), 'dbchat.toml');
            console.log('Config path:', configPath);

            let config: any = {
                connections: {},
                llm: {}
            };
            console.log('Initial config structure:', config);

            // Read existing config if it exists
            try {
                console.log('Attempting to read existing config file...');
                const fileContent = await fs.readFile(configPath, 'utf-8');
                console.log('Existing file content:', fileContent);

                console.log('Parsing TOML content...');
                config = TOML.parse(fileContent);
                console.log('Parsed config:', config);

                // Ensure connections section exists
                config.connections = config.connections || {};
                console.log('Config after ensuring connections exist:', config);
            } catch (error: any) {
                console.log('Error reading config:', error);
                if (error.code !== 'ENOENT') {
                    console.error('Unexpected error reading config:', error);
                    throw error;
                }
                console.log('Config file does not exist, will create new one');
            }

            // Check if connection already exists
            if (config.connections[name]) {
                console.log(`Connection "${name}" already exists, showing confirmation dialog`);
                const choice = await vscode.window.showWarningMessage(
                    `Connection "${name}" already exists. Do you want to overwrite it?`,
                    'Yes',
                    'No'
                );
                console.log('User choice for overwrite:', choice);

                if (choice !== 'Yes') {
                    console.log('User declined to overwrite, returning false');
                    return false;
                }
            }

            // Update the connection
            config.connections[name] = connectionString;
            console.log('Updated config:', config);

            // Convert config to TOML and write back to file
            console.log('Converting config to TOML...');
            const tomlContent = TOML.stringify(config);
            console.log('Generated TOML content:', tomlContent);

            // Preserve the header comments
            const finalContent = `# DBChat Sample Configuration File
# Copy this file to ~/.dbchat.toml and modify as needed

${tomlContent}`;
            console.log('Final content to write:', finalContent);

            console.log('Writing to file...');
            await fs.writeFile(configPath, finalContent, 'utf-8');
            console.log('File written successfully');

            // Update view immediately after successful file write
            this._showingConnectionForm = false;
            console.log('Form hidden, updating view');
            this._updateView();

            await vscode.window.showInformationMessage(`Connection "${name}" saved successfully!`, { modal: false });
            return true;
        } catch (error) {
            console.error('Error in _saveConnection:', error);
            if (error instanceof Error) {
                console.error('Error stack:', error.stack);
            }
            await vscode.window.showErrorMessage(`Failed to save connection: ${error}`);
            return false;
        }
    }
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List Connections

    private async _getConnections(): Promise<{[key: string]: string}> {
        try {
            const configPath = path.join(os.homedir(), 'dbchat.toml');
            const fileContent = await fs.readFile(configPath, 'utf-8');
            const config = TOML.parse(fileContent);
            return config.connections || {};
        } catch (error) {
            console.error('Error reading connections:', error);
            return {};
        }
    }
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Delete Connections

    private async _deleteConnection(name: string): Promise<boolean> {
        try {
            const configPath = path.join(os.homedir(), 'dbchat.toml');
            const fileContent = await fs.readFile(configPath, 'utf-8');
            const config = TOML.parse(fileContent);

            if (!config.connections || !config.connections[name]) {
                await vscode.window.showErrorMessage(`Connection "${name}" not found.`);
                return false;
            }

            delete config.connections[name];

            const tomlContent = TOML.stringify(config);
            const finalContent = `# DBChat Sample Configuration File
# Copy this file to ~/.dbchat.toml and modify as needed

${tomlContent}`;

            await fs.writeFile(configPath, finalContent, 'utf-8');
            // Show message after file operations are complete
            vscode.window.showInformationMessage(`Connection "${name}" deleted successfully.`);
            return true;
        } catch (error) {
            console.error('Error deleting connection:', error);
            vscode.window.showErrorMessage(`Failed to delete connection: ${error}`);
            return false;
        }
    }
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That's about it for this post. With this structure - we implemented a basic database connection listing, add, delete & update operations.

Next Steps

Since we have a primitive database configuration mechanism, next we will aim to enable connecting to a particular configuration, obtaining schema, chat with DB, etc - using the golang LSP.

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