c# - 如何在 .NET Core 中读取 connectionString WITH PROVIDER？

Question

我加了

.AddJsonFile("Connections.json", optional: true, reloadOnChange: true)

在

 public Startup(IHostingEnvironment env)

Connections.json 包含:

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=(localdb)\\mssqllocaldb;Database=DATABASE;Trusted_Connection=True;MultipleActiveResultSets=true",
    "COR-W81-101": "Data Source=DATASOURCE;Initial Catalog=P61_CAFM_Basic;User Id=USERID;Password=PASSWORD;Persist Security Info=False;MultipleActiveResultSets=False;Packet Size=4096;",
    "COR-W81-100": "Data Source=DATASOURCE;Initial Catalog=Post_PS;User Id=USERID;Password=PASSWORD;Persist Security Info=False;MultipleActiveResultSets=False;Packet Size=4096;",
    "MSEDGEWIN10": "Data Source=DATASOURCE; Initial Catalog=COR_Basic; Persist Security Info=False;Integrated Security=true;MultipleActiveResultSets=False;Packet Size=4096;Application Name=\"COR_Basic\"",

    "server": "Data Source=DATASOURCE; Initial Catalog=COR_Basic; Persist Security Info=False;User Id=USERID;Password=PASSWORD;MultipleActiveResultSets=False;Packet Size=4096;Application Name=\"COR_Basic\""
  },


  "conStrings": [
      {
        "name": "COR-W81-101",     
        "connectionString": "Data Source=DATASOURCE; Initial Catalog=COR_Basic; Persist Security Info=False;Integrated Security=true;MultipleActiveResultSets=False;Packet Size=4096;Application Name=\"COR_Basic\"",
        "providerName": "System.Data.SqlClient"
      }

    },

    {
      "name": "server",
      "connectionString": "Data Source=DATASOURCE; Initial Catalog=COR_Basic; Persist Security Info=False;Integrated Security=true;MultipleActiveResultSets=False;Packet Size=4096;Application Name=\"COR_Basic\"",
      "providerName": "System.Data.SqlClient"
    }
  ],



  "conStringDictionary": {
    "COR-W81-101": {
      "connectionString": "Data Source=DATASOURCE; Initial Catalog=COR_Basic; Persist Security Info=False;Integrated Security=true;MultipleActiveResultSets=False;Packet Size=4096;Application Name=\"COR_Basic\"",
      "providerName": "System.Data.SqlClient"
    },

    "server": {
      "connectionString": "Data Source=DATASOURCE; Initial Catalog=COR_Basic; Persist Security Info=False;Integrated Security=true;MultipleActiveResultSets=False;Packet Size=4096;Application Name=\"COR_Basic\"",
      "providerName": "System.Data.SqlClient"
    }

  }
}

现在我想读取 connectionStrings:

public class ConnectionString
{
    public string name { get; set; }
    public string connectionString { get; set; }
    public string providerName { get; set; }
}

像这样:

//Microsoft.Extensions.DependencyInjection.OptionsConfigurationServiceCollectionExtensions.Configure<ConnectionString[]>(services, Configuration.GetSection("conStrings"));

// https://stackoverflow.com/questions/31929482/retrieve-sections-from-config-json-in-asp-net-5
//var objectSections = Configuration.GetSection("conStringDictionary").GetChildren();
//foreach (var x in objectSections)
//{
//    System.Console.WriteLine(x.Key);
//    var cs = new ConnectionString();
//    ConfigurationBinder.Bind(x, cs);
//    System.Console.WriteLine(cs);
//}

// http://andrewlock.net/how-to-use-the-ioptions-pattern-for-configuration-in-asp-net-core-rc2/
        Microsoft.Extensions.DependencyInjection.OptionsConfigurationServiceCollectionExtensions.Configure<Dictionary<string, ConnectionString>>(services, Configuration.GetSection("conStrings"));

但我无法让它读取数组或字典。我需要每个 connectionString 的 providerName，并且我希望它与连接字符串位于同一条目中，但不作为连接字符串。

Answer 1

基本上，您所要做的就是创建一些强类型类来匹配旧的 ConnectionStringSettings 并利用一些集合序列化逻辑。

以下是我建议如何将它们格式化为 json。与您使用旧的 XML app/web.config 方式指定连接字符串的方式非常相似。作为键的连接字符串的名称。

{
  "ConnectionStrings": {
    "Test1": {
      "ConnectionString": "server=localhost;database=db;username=user;password=pass;",
      "ProviderName": "MySql.Data.MySqlClient"
    },
    "Test2": {
      "ConnectionString": "server=localhost;database=db2;username=user2;password=pass2;",
      "ProviderName": "MySql.Data.MySqlClient"
    }
  }
}

现在是要绑定(bind)的类。首先是简单的 ConnectionStringSettings 类本身，实现您的基本相等/散列方法(这是必要的，因为我们打算将其粘贴在字典中)。

public class ConnectionStringSettings
{
    public String Name { get; set; }
    public String ConnectionString { get; set; }
    public String ProviderName { get; set; }

    public ConnectionStringSettings()
    {
    }

    public ConnectionStringSettings(String name, String connectionString)
        : this(name, connectionString, null)
    {
    }

    public ConnectionStringSettings(String name, String connectionString, String providerName)
    {
        this.Name = name;
        this.ConnectionString = connectionString;
        this.ProviderName = providerName;
    }

    protected bool Equals(ConnectionStringSettings other)
    {
        return String.Equals(Name, other.Name) && String.Equals(ConnectionString, other.ConnectionString) && String.Equals(ProviderName, other.ProviderName);
    }

    public override bool Equals(Object obj)
    {
        if (ReferenceEquals(null, obj)) return false;
        if (ReferenceEquals(this, obj)) return true;
        if (obj.GetType() != this.GetType()) return false;
        return Equals((ConnectionStringSettings) obj);
    }

    public override int GetHashCode()
    {
        unchecked
        {
            int hashCode = (Name != null ? Name.GetHashCode() : 0);
            hashCode = (hashCode * 397) ^ (ConnectionString != null ? ConnectionString.GetHashCode() : 0);
            hashCode = (hashCode * 397) ^ (ProviderName != null ? ProviderName.GetHashCode() : 0);
            return hashCode;
        }
    }

    public static bool operator ==(ConnectionStringSettings left, ConnectionStringSettings right)
    {
        return Equals(left, right);
    }

    public static bool operator !=(ConnectionStringSettings left, ConnectionStringSettings right)
    {
        return !Equals(left, right);
    }
}

接下来是 ConnectionStringSettings 的集合。这是必需的，因为连接字符串的名称是 JSON 表示法中的键。为了保持该名称始终如一，我们需要覆盖 Dictionary 的 Add 方法(但您不能这样做，因为它不是虚拟的)。所以我们真正做的只是在我们自己的 Add 实现中用额外的位在内部包装一个 Dictionary 。同样，这看起来像很多代码，但您会发现它们非常单调乏味。

public class ConnectionStringSettingsCollection : IDictionary<String, ConnectionStringSettings>
{
    private readonly Dictionary<String, ConnectionStringSettings> m_ConnectionStrings;

    public ConnectionStringSettingsCollection()
    {
        m_ConnectionStrings = new Dictionary<String, ConnectionStringSettings>();
    }

    public ConnectionStringSettingsCollection(int capacity)
    {
        m_ConnectionStrings = new Dictionary<String, ConnectionStringSettings>(capacity);
    }

    #region IEnumerable methods
    IEnumerator IEnumerable.GetEnumerator()
    {
        return ((IEnumerable)m_ConnectionStrings).GetEnumerator();
    }
    #endregion

    #region IEnumerable<> methods
    IEnumerator<KeyValuePair<String, ConnectionStringSettings>> IEnumerable<KeyValuePair<String, ConnectionStringSettings>>.GetEnumerator()
    {
        return ((IEnumerable<KeyValuePair<String, ConnectionStringSettings>>)m_ConnectionStrings).GetEnumerator();
    }
    #endregion

    #region ICollection<> methods
    void ICollection<KeyValuePair<String, ConnectionStringSettings>>.Add(KeyValuePair<String, ConnectionStringSettings> item)
    {
        ((ICollection<KeyValuePair<String, ConnectionStringSettings>>)m_ConnectionStrings).Add(item);
    }

    void ICollection<KeyValuePair<String, ConnectionStringSettings>>.Clear()
    {
        ((ICollection<KeyValuePair<String, ConnectionStringSettings>>)m_ConnectionStrings).Clear();
    }

    Boolean ICollection<KeyValuePair<String, ConnectionStringSettings>>.Contains(KeyValuePair<String, ConnectionStringSettings> item)
    {
        return ((ICollection<KeyValuePair<String, ConnectionStringSettings>>)m_ConnectionStrings).Contains(item);
    }

    void ICollection<KeyValuePair<String, ConnectionStringSettings>>.CopyTo(KeyValuePair<String, ConnectionStringSettings>[] array, Int32 arrayIndex)
    {
        ((ICollection<KeyValuePair<String, ConnectionStringSettings>>)m_ConnectionStrings).CopyTo(array, arrayIndex);
    }

    Boolean ICollection<KeyValuePair<String, ConnectionStringSettings>>.Remove(KeyValuePair<String, ConnectionStringSettings> item)
    {
        return ((ICollection<KeyValuePair<String, ConnectionStringSettings>>)m_ConnectionStrings).Remove(item);
    }

    public Int32 Count => ((ICollection<KeyValuePair<String, ConnectionStringSettings>>)m_ConnectionStrings).Count;
    public Boolean IsReadOnly => ((ICollection<KeyValuePair<String, ConnectionStringSettings>>)m_ConnectionStrings).IsReadOnly;
    #endregion

    #region IDictionary<> methods
    public void Add(String key, ConnectionStringSettings value)
    {
        // NOTE only slight modification, we add back in the Name of connectionString here (since it is the key)
        value.Name = key;
        m_ConnectionStrings.Add(key, value);
    }

    public Boolean ContainsKey(String key)
    {
        return m_ConnectionStrings.ContainsKey(key);
    }

    public Boolean Remove(String key)
    {
        return m_ConnectionStrings.Remove(key);
    }

    public Boolean TryGetValue(String key, out ConnectionStringSettings value)
    {
        return m_ConnectionStrings.TryGetValue(key, out value);
    }

    public ConnectionStringSettings this[String key]
    {
        get => m_ConnectionStrings[key];
        set => Add(key, value);
    }

    public ICollection<String> Keys => m_ConnectionStrings.Keys;
    public ICollection<ConnectionStringSettings> Values => m_ConnectionStrings.Values;
    #endregion
}

几个简单的扩展方法，让事情变得更简单。

public static class ConnectionStringSettingsExtensions
{
    public static ConnectionStringSettingsCollection ConnectionStrings(this IConfigurationRoot configuration, String section = "ConnectionStrings")
    {
        var connectionStringCollection = configuration.GetSection(section).Get<ConnectionStringSettingsCollection>();
        if (connectionStringCollection == null)
        {
            return new ConnectionStringSettingsCollection();
        }

        return connectionStringCollection;
    }

    public static ConnectionStringSettings ConnectionString(this IConfigurationRoot configuration, String name, String section = "ConnectionStrings")
    {
        ConnectionStringSettings connectionStringSettings;

        var connectionStringCollection = configuration.GetSection(section).Get<ConnectionStringSettingsCollection>();
        if (connectionStringCollection == null ||
            !connectionStringCollection.TryGetValue(name, out connectionStringSettings))
        {
            return null;
        }

        return connectionStringSettings;
    }
}

最后是用法。

var configuration = new ConfigurationBuilder()
    .AddJsonFile("config.json")
    .Build();

var connectionStrings = configuration.ConnectionStrings();

foreach (var connectionString in connectionStrings.Values)
{
    Console.WriteLine(connectionString.Name);
    Console.WriteLine(connectionString.ConnectionString);
    Console.WriteLine(connectionString.ProviderName);
}

var specificConnStr1 = connectionStrings["Test1"];
Console.WriteLine(specificConnStr1.Name);
Console.WriteLine(specificConnStr1.ConnectionString);
Console.WriteLine(specificConnStr1.ProviderName);

var specificConnStr2 = configuration.ConnectionString("Test2");
Console.WriteLine(specificConnStr2.Name);
Console.WriteLine(specificConnStr2.ConnectionString);
Console.WriteLine(specificConnStr2.ProviderName);