节点Sqlite3错误

如何解决节点Sqlite3错误

我在node中使用sqlite3包，并开始刷新我的REST API。我决定围绕DB调用并在控制器中创建一个Promise包装器，使用async / await调用这些函数并将返回值设置为变量。然后，检查变量并设置响应对象。对于成功的案例，它运作良好，找到了解决办法，并做出了回应。问题是，在sqlite3中，我很难检查错误。我对DB服务中的undefined进行了基本检查，如果遇到错误，它确实会引发错误，但是该错误会立即转到控制器的CATCH部分，并且不允许我将其包装在我想要的API响应中喜欢定义。这些是单独的文件（控制器与服务）。在sqlite3的错误检查方面，我找不到很多有用的信息，因为它稀疏。理想情况下，服务会引发错误，然后我可以将其包装到标准化响应对象中并发送。

------位置

const getById = async (req,res,next) => {
    response = {};
    try {
        let location = await getLocationById(req.params.id); // <-- IF NO VALUE FOUND,location IS nothing
        if (error) { // <----- THIS IS WHERE I'D LIKE TO CHECK FOR ERRORS.
            response.status = 404;
            response.message = 'Error attempting to get location';
        } else {
            response.status = 200;
            response.message = 'Success';
            response.data = location;
        }
        res.json(response);
    } catch (error) {
        res.json(response);
    }
};

------------服务

const getLocationById = (id) => {
    return new Promise((resolve,reject) => {
        let sql = 'SELECT * FROM Locations WHERE id = ?;';
        db.get(sql,[id],(error,location) => {
            if (location !== undefined) {
                resolve(location);
            } else {
                reject(new Error('Error attempting to get location by id'));
            }
        });
    });
};

解决方法

您只需要将对getLocationById()的调用包装到另一个try/catch中。从那里，您可以决定要包装还是引发错误。如果没有要添加的其他代码可能会引发错误，则可以删除外部的try/catch。内嵌评论中的更多解释和建议：

const getLocationById = (id) => {
  return new Promise((resolve,reject) => {
    const sql = "SELECT * FROM Locations WHERE id = ?;";
    db.get(sql,[id],(error,location) => {
      // check for an error from the db here
      if (error) return reject(error);
      // check for an empty result here and throw your own error
      if (!location) {
        // set a property so we can tell that it wasn't a db error just not found
        const myError = new Error("Error attempting to get location by id");
        myError.notFound = true;
        return reject(myError);
      }
      // otherwise resolve the result
      return resolve(location);
    });
  });
};

const getById = async (req,res,next) => {
  // use const since it is not reassigned,only properties are changed
  const response = {};
  try {
    // code here that might throw an exception
    try {
      // use const if you aren't going to reassign `location`
      const location = await getLocationById(req.params.id); 
      
      // we were able to load the location if we get here
      response.status = 200;
      response.message = "Success";
      response.data = location;
    } catch (error) {
      // maybe check to see if we want to wrap or raise the error
      // maybe call console.log(error) to see the contents
      const doWeWantToWrapTheError = somethingToCheckTypeEtc(error);
      if (doWeWantToWrapTheError) {
        if (error.notFound) {
          // no db errors,just not found
          response.status = 404;
        } else {
          // some kind of db error so set to "internal server error"
          response.status = 500;
        }
        response.message = "Error attempting to get location";
      } else {
        // raise the error to the outer try/catch
        throw error;
      }
    }
    // code here that might throw an exception
    return res.json(response);
  } catch (unexpected) {
    // some other error occurred that was not caught above (unlikely)
    // maybe call console.log(unexpected) to see the contents
    response.error = unexpected.message;
    return res.json(response);
  }
};