src/Library/NetPro.Dapper/Expressions/DapperSmartAsync.cs

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using Dapper;
using System;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace NetPro.Dapper.Expressions
{
    /// <summary>
    ///  DapperSmart异步方法扩展
    /// </summary>
    public static partial class DapperSmart
    {
        /// <summary>
        /// <para>By default queries the table matching the class name asynchronously </para>
        /// <para>-Table name can be overridden by adding an attribute on your class [Table("YourTableName")]</para>
        /// <para>By default filters on the Id column</para>
        /// <para>-Id column name can be overridden by adding an attribute on your primary key property [Key]</para>
        /// <para>Supports transaction and command timeout</para>
        /// <para>Returns a single entity by a single id from table T</para>
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="connection"></param>
        /// <param name="id"></param>
        /// <param name="transaction"></param>
        /// <param name="commandTimeout"></param>
        /// <returns>Returns a single entity by a single id from table T.</returns>
        public static async Task<T> QueryAsync<T>(this IDbConnection connection, object id, IDbTransaction transaction = null, int? commandTimeout = null)
        {
            var currenttype = typeof(T);
            var idProps = GetIdProperties(currenttype).ToList();

            if (!idProps.Any())
                throw new ArgumentException("Get<T> only supports an entity with a [Key] or Id property");

            var name = GetTableName(currenttype);
            var sb = new StringBuilder();
            sb.Append("Select ");
            //create a new empty instance of the type to get the base properties
            BuildSelect(sb, GetScaffoldableProperties<T>().ToArray());
            sb.AppendFormat(" from {0} where ", name);

            for (var i = 0; i < idProps.Count; i++)
            {
                if (i > 0)
                    sb.Append(" and ");
                sb.AppendFormat("{0} = @{1}", GetColumnName(idProps[i]), idProps[i].Name);
            }

            var dynParms = new DynamicParameters();
            if (idProps.Count == 1)
                dynParms.Add("@" + idProps.First().Name, id);
            else
            {
                foreach (var prop in idProps)
                    dynParms.Add("@" + prop.Name, id.GetType().GetProperty(prop.Name).GetValue(id, null));
            }