db-mcp-tool

Implementation Reference

• src/index.ts:289-320 (registration)

  Registers the "!export-data" MCP tool. Defines the input schema (table name) and the handler function that delegates to DatabaseService.exportTableData().

  server.tool(
    "!export-data",
    {
      table: z.string(),
    },
    async (args: { table: string }) => {
      if (!dbService) {
        return {
          content: [{ type: "text", text: "You must connect to a database first!" }],
          isError: true,
        };
      }
  
      try {
        const data = await dbService.exportTableData(args.table);
        return {
          content: [
            {
              type: "text",
              text: data,
            },
          ],
        };
      } catch (error: unknown) {
        const errorMessage = error instanceof Error ? error.message : 'Unknown error';
        return {
          content: [{ type: "text", text: `Failed to export table data: ${errorMessage}` }],
          isError: true,
        };
      }
    }
  );

• src/index.ts:294-319 (handler)

  The direct handler function for the "!export-data" tool, which validates the database connection and invokes the service method.

  async (args: { table: string }) => {
    if (!dbService) {
      return {
        content: [{ type: "text", text: "You must connect to a database first!" }],
        isError: true,
      };
    }
  
    try {
      const data = await dbService.exportTableData(args.table);
      return {
        content: [
          {
            type: "text",
            text: data,
          },
        ],
      };
    } catch (error: unknown) {
      const errorMessage = error instanceof Error ? error.message : 'Unknown error';
      return {
        content: [{ type: "text", text: `Failed to export table data: ${errorMessage}` }],
        isError: true,
      };
    }
  }

• src/index.ts:291-293 (schema)

  Zod input schema for the tool: requires a 'table' string parameter.

  {
    table: z.string(),
  },

• src/services/database.ts:263-331 (helper)

  Core helper method in DatabaseService that exports table data as SQL INSERT statements for PostgreSQL and MySQL.

  async exportTableData(tableName: string): Promise<string> {
      switch (this.config.type) {
          case 'postgres': {
              if (!this.postgresClient) {
                  throw new Error('PostgreSQL connection not found');
              }
  
              // Önce tablo verilerini al
              const dataQuery = `SELECT * FROM ${tableName};`;
              const result = await this.postgresClient.query(dataQuery);
  
              if (result.rows.length === 0) {
                  return '';
              }
  
              // Sütun isimlerini al
              const columns = Object.keys(result.rows[0]);
  
              // INSERT ifadelerini oluştur
              const insertStatements = result.rows.map(row => {
                  const values = columns.map(col => {
                      const val = row[col];
                      if (val === null) return 'NULL';
                      if (typeof val === 'string') return `'${val.replace(/'/g, "''")}'`;
                      return val;
                  });
                  return `INSERT INTO ${tableName} (${columns.join(', ')}) VALUES (${values.join(', ')});`;
              });
  
              return insertStatements.join('\n');
          }
          case 'mysql': {
              if (!this.mysqlConnection) {
                  throw new Error('MySQL connection not found');
              }
  
              // Önce tablo verilerini al
              const [rows] = await this.mysqlConnection.query(
                  'SELECT * FROM ??',
                  [tableName]
              );
  
              if (rows.length === 0) {
                  return '';
              }
  
              // Sütun isimlerini al
              const columns = Object.keys(rows[0]);
  
              // INSERT ifadelerini oluştur
              const insertStatements = rows.map((row: any) => {
                  const values = columns.map(col => {
                      const val = row[col];
                      if (val === null) return 'NULL';
                      if (typeof val === 'string') return `'${val.replace(/'/g, "''")}'`;
                      return val;
                  });
                  return `INSERT INTO ${tableName} (${columns.join(', ')}) VALUES (${values.join(', ')});`;
              });
  
              return insertStatements.join('\n');
          }
          case 'firestore': {
              throw new Error('SQL data export is not supported for Firestore');
          }
          default:
              throw new Error('Unsupported database type');
      }
  }