御用小本本

Nuget

Microsoft.EntityFrameworkCore.Design

Npgsql.EntityFrameworkCore.PostgreSQL

Code

using System;
using System.Linq;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;

namespace ConsoleApp1
{
    public class Program
    {
        public static readonly ILoggerFactory MyLoggerFactory
            = LoggerFactory.Create(builder => { builder.AddConsole(); });
        
        public static void Main(string[] args)
        {
            using (var db = new BloggingContext())
            {
                // Read
                Console.WriteLine("Querying for a blog start...");
                var blogs = db.Blogs.Where(x => x.BlogId > 1).AsEnumerable();
                var blog = blogs.FirstOrDefault();
                Console.WriteLine($"{blog?.Url}");
                var blog2 = blogs.Where(x => x.BlogId == 5).FirstOrDefault();
                Console.WriteLine($"{blog2?.Url}");
                Console.WriteLine("Querying for a blog finish...");
            }
        }
    }
    
    public class BloggingContext : DbContext
    {
        public DbSet<Blog> Blogs { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
            => optionsBuilder
                .UseLoggerFactory(Program.MyLoggerFactory)
                .UseNpgsql("Host=127.0.0.1;Database=jake;Username=jake;Password=jake",
                    options => options.SetPostgresVersion(new Version(9, 6)));
    }

    public class Blog
    {
        public int BlogId { get; set; }
        public string Url { get; set; }
    }
}

Migrations 有問題記得設定 PostgreSQL 版本

SetPostgresVersion

設定後 Remove Migrations 再整個重建

因為建立表的欄位自動增長語法有改動

PostgreSQL 10

CREATE TABLE distributors (
     did    integer PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
     name   varchar(40) NOT NULL CHECK (name <> '')
);

PostgreSQL 9.x

CREATE TABLE distributors (
     did    integer PRIMARY KEY DEFAULT nextval('serial'),
     name   varchar(40) NOT NULL CHECK (name <> '')
);

參考

開始使用 EF Core

EF Core 記錄

Npgsql Entity Framework Core Provider

Generated Columns Not Compatible with PSQL 9.x

PostgreSQL 9.6.19 Documentation

PostgreSQL 10 Documentation