ConnectionString 属性尚未初始化。(网上找了哈没解决)

Question

ConnectionString 属性尚未初始化。 
说明: 执行当前 Web 请求期间，出现未处理的异常。请检查堆栈跟踪信息，以了解有关该错误以及代码中导致错误的出处的详细信息。 异常详细信息: System.InvalidOperationException: ConnectionString 属性尚未初始化。
using System;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Collections.Generic;
using System.Text;namespace DataAccess
{
    public class BaseAccess
    {
        string conStr = ConfigurationSettings.AppSettings["databaseString"];
        string fileUpPath = ConfigurationSettings.AppSettings["FileUpPath"]; 
        
        //返回字符串
        protected string GetSingleValue(string sqlStr,bool IsProc,params SqlParameter[] param)
        {
           SqlConnection con = new SqlConnection(this.conStr);
            SqlCommand cmd = new SqlCommand(sqlStr,con);
            if (IsProc)
            {
                cmd.CommandType = CommandType.StoredProcedure;
            }
            foreach (SqlParameter p in param)
            {
                cmd.Parameters.Add(p);
            }
            try
            {
                con.Open();
                return cmd.ExecuteScalar().ToString();
            }
            catch (Exception ex)
            {
                throw ex;
    
            }
            finally
            {
                con.Close();
            }
        }        //返回DATASET
        protected DataSet GetDataByDS(string sqlStr, string tableName, bool IsProc, params SqlParameter[] param)
        {
            SqlConnection con = new SqlConnection(conStr);
            SqlCommand cmd = new SqlCommand(sqlStr,con);
            if (IsProc)
            {
                cmd.CommandType = CommandType.StoredProcedure;
            }
            foreach (SqlParameter p in param)
            {
                cmd.Parameters.Add(p);
            }
            DataSet ds = new DataSet();
            try
            {
                SqlDataAdapter adapter = new SqlDataAdapter(cmd);
                adapter.Fill(ds,tableName);
                return ds;
            }
            catch (Exception ex)
            {
                throw ex;//这里报错
            }
            finally
            {
                con.Close();
            }
        }
        //返回DATASET
        protected DataSet GetMultiTable(string[] sqlStr, string[] tableName, bool IsProc, params SqlParameter[] param)
        {
            SqlConnection con = new SqlConnection(this.conStr);
            SqlCommand cmd1 = new SqlCommand(sqlStr[0], con);
            SqlCommand cmd2 = new SqlCommand(sqlStr[1], con);
            if (IsProc)
            {
                cmd1.CommandType = CommandType.StoredProcedure;
                cmd2.CommandType = CommandType.StoredProcedure;
            }
            int num = 0;
            foreach (SqlParameter p in param)
            {
                if (num < 1)
                {
                    cmd1.Parameters.Add(p);
                }
                else
                {
                    cmd2.Parameters.Add(p);
                }
                num++;
            }           
            DataSet ds = new DataSet();
            try
            {
                SqlDataAdapter adapter1 = new SqlDataAdapter(cmd1);
                SqlDataAdapter adapter2 = new SqlDataAdapter(cmd2);
                adapter1.Fill(ds,tableName[0]);
                adapter2.Fill(ds,tableName[1]);
                return ds;
            }
            catch (Exception ex)
            {
                throw ex;
            }
                    }
        //执行SQL语句
        protected int ExecuteSql(string sqlStr, bool IsProc, params SqlParameter[] param)
        {
            SqlConnection con = new SqlConnection(this.conStr);
            SqlCommand cmd = new SqlCommand(sqlStr, con);
            if (IsProc)
            {
                cmd.CommandType = CommandType.StoredProcedure;
            }
            foreach (SqlParameter p in param)
            {
                cmd.Parameters.Add(p);
            }
            try
            {
                con.Open();
                return cmd.ExecuteNonQuery();
                //return cmd.ExecuteScalar().ToString();
            }
            catch (Exception ex)
            {
                throw ex;
               
            }
            finally
            {
                con.Close();
            }
             
        }
        //返回执行的后的最大ＩＤ
        protected int GetTopId(string TableName) {
            SqlConnection con = new SqlConnection(this.conStr);
           string sqlStr="select @@indentity as id from "+TableName;
           SqlCommand cmd=new SqlCommand(sqlStr,con);
           int id =Convert.ToInt32(cmd.ExecuteScalar());
           return id;
        }
    }
}
app.config代码 
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
 </configSections> <appSettings>
<add key="databaseString" value="Data Source=156.1.5.225;Initial Catalog=changweiban;Persist Security Info=True;User ID=sa;Password=jcb1311"/>
<add key="FileUpPath" value="./"/>
</appSettings>
</configuration>

Answer 1

webform
那要用web.config

Answer 2

你把
 <appSettings>
        <add key="databaseString" value="Data Source=156.1.5.225;Initial Catalog=changweiban;Persist Security Info=True;User ID=sa;Password=jcb1311"/>
        <add key="FileUpPath" value="./"/>
    </appSettings>这段加到Web.config文件中ConfigurationSettings引用的是Web项目下的Web.config
而不是被引用的项目的App.config

Answer 3

添加System.Configuration
System.Configuration.ConfigurationManager.AppSettings["databaseString"];

Answer 4

把
con.Open();
放在
SqlCommand cmd = new SqlCommand(sqlStr,con);
前面

Answer 5

应该还是得用web.config 

Answer 6

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <configSections>
    </configSections>
    <connectionStrings>
        <add name="testTreeView.Properties.Settings.cwbase1ConnectionString"
            connectionString="Data Source=.;Initial Catalog=cw;Persist Security Info=True;User ID=sa;Password=aaaaaa"
            providerName="System.Data.SqlClient" />
    </connectionStrings>
</configuration>
调用
            String connstring = global::testTreeView.Properties.Settings.Default.cwbase1ConnectionString;
            SqlConnection conn = new SqlConnection(connstring);

Answer 7

我想这个错误应该不是因为是App.config导致!研究一下!

Answer 8

  <connectionStrings>
    <add name="ConnectionString" connectionString="" providerName="System.Data.SqlClient"/>
  </connectionStrings>推荐这种写法

Answer 9

用
ConfigurationManager.AppSettings["databaseString"]