psycopg2.ProgrammingError：无法递归重新进入连接

Question

我使用 React 的 fetch api 从 Flask 调用端点。我不断收到 psycopg2.ProgrammingError: 连接无法递归重新输入

I 端点调用位于循环内。

@app.get("/api/plot-project/<int:plot_id>/<int:project_id>")
def check_and_deactivate(plot_id, project_id):
    with connection:
        with connection.cursor() as cursor:
            cursor.execute(PLOT_PROJECT_CHECK, (plot_id, project_id))
            data = cursor.fetchall()
            if len(data) == 0:
                return "No data found", 404
            removed = data.pop(0)
            if  len(data) > 1:
                for row in data:
                    print(row[0])
                    cursor.execute(PLOT_PROJECT_DEACTIVATE, ('deleted', row[0], plot_id, project_id))
            return { "Remain": removed }, 200   

反应功能

  const handleGet = () => {
    data.forEach (async (item) => {
      
      await getData(item.plotID, item.projectID);
    })
  }

获取句柄

  const getData = async (plotID, projectID) => { 
    fetch(`http://127.0.0.1:5000/api/plot-project/${plotID}/${projectID}`, {  method : 'GET',  mode: 'no-cors', headers : {    'Content-Type': 'application/json',    'Authorization': `Bearer ${token}`  }})
      .then(data => data.json())
      .then((response) => {
        console.log('mapping', plotID, "to", projectID)
        console.log('request succeeded with JSON response', response)
      }).catch(function (error) {
        console.log('mapping', plotID, "to", projectID)
        console.log('no mapping yet')
      });
  }

Answer 1

当您尝试调用同一连接的上下文管理器（该连接已在上下文管理器中调用）时，会发生此错误。

要解决该问题，您有几种选择：

• 在没有上下文管理器的情况下使用相同的连接并提交或回滚更改。代码如下所示：

    try:
        result = None
        with connection.cursor() as cursor:
            cursor.execute(PLOT_PROJECT_CHECK, (plot_id, project_id))
            data = cursor.fetchall()
            if len(data) == 0:
                result = "No data found", 404
            removed = data.pop(0)
            if  len(data) > 1:
                for row in data:
                    print(row[0])
                    cursor.execute(PLOT_PROJECT_DEACTIVATE, ('deleted', row[0], plot_id, project_id))
            result = { "Remain": removed }, 200   
            conn.commit()
        return result
        except Exception as e:
            logging.error(f"An error occurred: {str(e)}")
            conn.rollback()
        return "Database error", 500

• 在没有上下文管理器的情况下使用相同的连接并使用自动提交。代码如下所示：

    connection.autocommit = True (you can place that code where you are making the connection)
    with connection.cursor() as cursor:
        cursor.execute(PLOT_PROJECT_CHECK, (plot_id, project_id))
        data = cursor.fetchall()
        if len(data) == 0:
            return "No data found", 404
        removed = data.pop(0)
        if len(data) > 1:
            for row in data:
            print(row[0])
            cursor.execute(PLOT_PROJECT_DEACTIVATE, ('deleted', row[0], plot_id, project_id))
            return { "Remain": removed }, 200   

• 使用连接池并为每个请求进入单独连接的上下文管理器。