我來幫你創建一個C#程序，從PostgreSQL數據庫讀取表結構并生成對應的實體類文件。我已經創建了一個完整的PostgreSQL實體類生成器。這個程序包含以下主要功能：
主要特性
- 數據庫連接: 使用Npgsql連接PostgreSQL數據庫
- 表結構讀取: 自動讀取所有表的結構信息
- 類型映射: 將PostgreSQL數據類型映射為C#數據類型
- 實體生成: 為每個表生成對應的C#實體類
- 文件導出: 將生成的類保存到指定文件夾
使用方法
安裝NuGet包:
Install-Package Npgsql配置連接字符串: 修改Main方法中的連接字符串：
var connectionString = "Host=localhost;Database=your_database;Username=your_username;Password=your_password;";設置輸出路徑:
var outputPath = @"C:\GeneratedEntities";運行程序: 執行后會自動生成所有表的實體類
生成的實體類特點
- 包含完整的Data Annotations特性
- 主鍵字段標記為
[Key] - 字段映射使用
[Column]特性 - 支持可空類型
- 字符串長度限制
- 帕斯卡命名法（下劃線轉換）
支持的數據類型
- 整數類型：int, long, short
- 浮點類型：float, double, decimal
- 文本類型：string
- 日期時間：DateTime, DateTimeOffset, TimeSpan
- 其他：bool, Guid, byte[]
生成的實體類可以直接用于Entity Framework Core或其他ORM框架。
1.try cath 寫在哪里? 寫在 ViewModel層 Servace層最多使用自定義異常業務異常進行處理(傳給ViewModel層處理), DAO層進行數據庫操作流水賬式,但是要做好資源釋放操作
2.DbHelp 是什么模式?單例?釋放需要手動釋放?單例模式(和項目的整個聲明周期一起,關了就完蛋了),不需要關閉(和項目的整個聲明周期一起,關了就完蛋了),無法批量插入是因為 表結構還沒完全構建完成,解決方法,先插入第一條來“預熱”連接,如果還有后續的數據,就直接進行批量插入.public async Task InitTestOrdersAsync(){await _db.DeleteTableAsync<Orders>();await _db.CreateTableAsync<Orders>();var mockOrders = new List<Orders>();// ... (生成 mockOrders 的代碼) ...if (mockOrders.Any()){// 1. 先插入第一條來“預熱”連接await _db.InsertAsync(mockOrders.First());// 2. 再批量插入剩下的數據var remainingOrders = mockOrders.Skip(1).ToList();if(remainingOrders.Any()){await _db.InsertAllAsync(remainingOrders);}}}3.弄清 異步和非異步方法的區別,以及使用場景
只要底層（DAO 和 HttpClient）是異步的，Service 層 和 ViewModel 層也都必須是異步的！也就是說：要一路 async 到頂層。
| 層級 | 是否 async | 原因 |
| ----------------------------- | -------- | --------------------- |
| DAO（使用 SQLiteAsyncConnection） | ? 必須異步 | SQLite 是 IO，使用異步 API |
| 調用 DAO 的 Service | ? 必須異步 | 調用異步方法 → 必須用 `await` |
| 調用 Service 的 ViewModel | ? 必須異步 | 繼續 `await` service 結果 || 情況 | 是否 async |
| ---------------- | ----------- |
| 方法內部沒有任何異步調用 | ? 不需要 async |
| 方法只是封裝計算邏輯、純內存操作 | ? 不需要 async |你用的是 SQLiteAsyncConnection + HttpClient 這樣的異步庫，整個調用鏈（DAO → Service → ViewModel）都必須使用 async/await 才是正確做法。🎯 為什么 .Result 或 .Wait() 會“把線程卡住”？
原因是：
.Result 和 .Wait() 是同步阻塞方法，會強制當前線程“原地等到任務完成”，不能做別的事，也不會釋放線程。4.創建一個讀取postSQL數據庫的工具,生成實體類5432PostgreSQLEntityGenerator.cs
using System;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Text;
using Npgsql;namespace ConsoleApp1
{public class EntityGenerator{private readonly string _connectionString;private readonly string _outputPath;public EntityGenerator(string connectionString, string outputPath){_connectionString = connectionString;_outputPath = outputPath;}public void GenerateEntities(){try{// 確保輸出目錄存在if (!Directory.Exists(_outputPath)){Directory.CreateDirectory(_outputPath);}using (var connection = new NpgsqlConnection(_connectionString)){connection.Open();// 獲取所有表名var tables = GetTableNames(connection);foreach (var tableName in tables){Console.WriteLine($"正在生成實體類: {tableName}");GenerateEntityForTable(connection, tableName);}}Console.WriteLine($"實體類生成完成！輸出路徑: {_outputPath}");}catch (Exception ex){Console.WriteLine($"生成實體類時發生錯誤: {ex.Message}");throw;}}private List<string> GetTableNames(NpgsqlConnection connection){var tables = new List<string>();const string sql = @"SELECT table_name FROM information_schema.tables WHERE table_schema = 'public' AND table_type = 'BASE TABLE'ORDER BY table_name";using (var command = new NpgsqlCommand(sql, connection))using (var reader = command.ExecuteReader()){while (reader.Read()){tables.Add(reader.GetString("table_name"));}}return tables;}private void GenerateEntityForTable(NpgsqlConnection connection, string tableName){var columns = GetTableColumns(connection, tableName);var entityCode = GenerateEntityCode(tableName, columns);var fileName = $"{ToPascalCase(tableName)}.cs";var filePath = Path.Combine(_outputPath, fileName);File.WriteAllText(filePath, entityCode, Encoding.UTF8);}private List<ColumnInfo> GetTableColumns(NpgsqlConnection connection, string tableName){var columns = new List<ColumnInfo>();const string sql = @"SELECT c.column_name,c.data_type,c.is_nullable,c.column_default,c.character_maximum_length,c.numeric_precision,c.numeric_scale,CASE WHEN pk.column_name IS NOT NULL THEN true ELSE false END as is_primary_keyFROM information_schema.columns cLEFT JOIN (SELECT ku.column_nameFROM information_schema.table_constraints tcJOIN information_schema.key_column_usage kuON tc.constraint_name = ku.constraint_nameAND tc.table_schema = ku.table_schemaWHERE tc.constraint_type = 'PRIMARY KEY'AND tc.table_name = @tableNameAND tc.table_schema = 'public') pk ON c.column_name = pk.column_nameWHERE c.table_name = @tableNameAND c.table_schema = 'public'ORDER BY c.ordinal_position";using (var command = new NpgsqlCommand(sql, connection)){command.Parameters.AddWithValue("@tableName", tableName);using (var reader = command.ExecuteReader()){while (reader.Read()){columns.Add(new ColumnInfo{Name = reader.GetString("column_name"),DataType = reader.GetString("data_type"),IsNullable = reader.GetString("is_nullable") == "YES",DefaultValue = reader.IsDBNull("column_default") ? null : reader.GetString("column_default"),MaxLength = reader.IsDBNull("character_maximum_length") ? (int?)null : reader.GetInt32("character_maximum_length"),Precision = reader.IsDBNull("numeric_precision") ? (int?)null : reader.GetInt32("numeric_precision"),Scale = reader.IsDBNull("numeric_scale") ? (int?)null : reader.GetInt32("numeric_scale"),IsPrimaryKey = reader.GetBoolean("is_primary_key")});}}}return columns;}private string GenerateEntityCode(string tableName, List<ColumnInfo> columns){var sb = new StringBuilder();var className = ToPascalCase(tableName);// 添加using語句sb.AppendLine("using System;");sb.AppendLine("using System.ComponentModel.DataAnnotations;");sb.AppendLine("using System.ComponentModel.DataAnnotations.Schema;");sb.AppendLine();// 添加命名空間sb.AppendLine("namespace Entities");sb.AppendLine("{");// 添加Table特性sb.AppendLine($" [Table(\"{tableName}\")]");sb.AppendLine($" public class {className}");sb.AppendLine(" {");// 生成屬性foreach (var column in columns){GenerateProperty(sb, column);}sb.AppendLine(" }");sb.AppendLine("}");return sb.ToString();}private void GenerateProperty(StringBuilder sb, ColumnInfo column){var propertyName = ToPascalCase(column.Name);var csharpType = GetCSharpType(column);// 添加注釋sb.AppendLine();sb.AppendLine($" /// <summary>");sb.AppendLine($" /// {column.Name}");sb.AppendLine($" /// </summary>");// 添加特性if (column.IsPrimaryKey){sb.AppendLine(" [Key]");}sb.AppendLine($" [Column(\"{column.Name}\")]");if (!column.IsNullable && csharpType != "string"){sb.AppendLine(" [Required]");}if (column.MaxLength.HasValue && csharpType == "string"){sb.AppendLine($" [MaxLength({column.MaxLength.Value})]");}// 生成屬性sb.AppendLine($" public {csharpType} {propertyName} {{ get; set; }}");}private string GetCSharpType(ColumnInfo column){var baseType = column.DataType.ToLower() switch{"integer" or "int4" => "int","bigint" or "int8" => "long","smallint" or "int2" => "short","boolean" or "bool" => "bool","real" or "float4" => "float","double precision" or "float8" => "double","numeric" or "decimal" => "decimal","text" or "varchar" or "character varying" or "char" or "character" => "string","timestamp" or "timestamp without time zone" => "DateTime","timestamp with time zone" or "timestamptz" => "DateTimeOffset","date" => "DateTime","time" or "time without time zone" => "TimeSpan","uuid" => "Guid","json" or "jsonb" => "string","bytea" => "byte[]",_ => "object"};// 如果字段可為空且不是引用類型，添加?if (column.IsNullable && baseType != "string" && baseType != "byte[]" && baseType != "object"){return baseType + "?";}return baseType;}private string ToPascalCase(string input){if (string.IsNullOrEmpty(input))return input;var parts = input.Split('_', '-');var sb = new StringBuilder();foreach (var part in parts){if (!string.IsNullOrEmpty(part)){sb.Append(char.ToUpper(part[0]));if (part.Length > 1)sb.Append(part[1..].ToLower());}}return sb.ToString();}}public class ColumnInfo{public string Name { get; set; }public string DataType { get; set; }public bool IsNullable { get; set; }public string DefaultValue { get; set; }public int? MaxLength { get; set; }public int? Precision { get; set; }public int? Scale { get; set; }public bool IsPrimaryKey { get; set; }}
}
Program.cs
using ConsoleApp1;try
{// 配置數據庫連接字符串var connectionString = "Host=localhost;Database=postgres;Username=postgres;Password=123456;";// 配置輸出路徑var outputPath = @"C:\MySoft\PostgreSQL\Models";// 創建生成器實例var generator = new EntityGenerator(connectionString, outputPath);// 生成實體類generator.GenerateEntities();Console.WriteLine("按任意鍵退出...");Console.ReadKey();
}
catch (Exception ex)
{Console.WriteLine($"程序執行出錯: {ex.Message}");Console.WriteLine("按任意鍵退出...");Console.ReadKey();
}
Console.WriteLine("Hello, World!");
)