如何解決TypeError: The view function did not return a valid response in python flask api

Question

我正在嘗試從mongodb數據庫中檢索數據並嘗試將該響應傳遞給前端reactjs應用程序。

但是我收到這個錯誤，我找不到它發生的原因：

類型錯誤：視圖函數未返回有效響應。 返回類型必須是字符串、字典、元組、響應實例或可調用的 WSGI，但它是一個列表

我需要的是：

我需要檢索所有 mongodb 文檔並將其傳遞給前端應用程序，以便我可以使用 reactjs 將其映射到表格中。

這就是我正在嘗試的，這給了我錯誤：

@app.route("/bemployees", methods=["GET"])
def retrieve_all_documents():
    client = pymongo.MongoClient(
        "<url>"
    )

    # database
    db = client.cdap

    # collection (table)
    collection = db.predicted_values

    documents_ = []

    for b in collection.find():

        documents_.append({'Age' :b['Age'] ,'DailyRate': b['DailyRate'],
                   'DistanceFromHome': b['DistanceFromHome'] , 'EnvironmentSatisfaction': b['EnvironmentSatisfaction'],
                   'HourlyRate':b['HourlyRate'],'JobInvolvement': b['JobInvolvement'],
                   'JobLevel': b['JobLevel'],'JobSatisfaction' :b['JobSatisfaction'],
                   'MonthlyIncome': b['MonthlyIncome'], 'MonthlyRate' :b['MonthlyRate'],
                   'NumCompaniesWorked': b['NumCompaniesWorked'],'PercentSalaryHike' :b['PercentSalaryHike'],
                   'RelationshipSatisfaction': b['RelationshipSatisfaction'],'StandardHours' :b['StandardHours'],
                   'TotalWorkingYears': b['TotalWorkingYears'],'TrainingTimesLastYear' :b['TrainingTimesLastYear'],
                   'YearsAtCompany': b['YearsAtCompany'],'YearsInCurrentRole' :b['YearsInCurrentRole'],
                   'YearsSinceLastPromotion': b['YearsSinceLastPromotion'],'YearsWithCurrManager' :b['YearsWithCurrManager'],
                   'MaritalStatus_': b['MaritalStatus_'],'JobRole_' :b['JobRole_'],
                   'Gender_': b['Gender_'],'EducationField_' :b['EducationField_'],
                   'Department_': b['Department_'],'BusinessTravel_' :b['BusinessTravel_'],
                   'OverTime_': b['OverTime_'],'Over18_' :b['Over18_'],
                   'empName': b['empName'],'empID' :b['empID'],
                   'PerformanceScore': b['PerformanceScore'],
                   'id': str(b['_id']) })

    return documents_ 

有人可以幫我解決這個問題嗎？

Answer 1

Flask 視圖不能返回列表。 解決此問題的一種方法是將您的列表轉換為 JSON 字符串：

import json
from flask import Response

@app.route("/bemployees", methods=["GET"])
def retrieve_all_documents():
    client = pymongo.MongoClient(
        "<url>"
    )

    # database
    db = client.cdap

    # collection (table)
    collection = db.predicted_values

    documents_ = []

    for b in collection.find():

        documents_.append({'Age' :b['Age'] ,'DailyRate': b['DailyRate'],
                   'DistanceFromHome': b['DistanceFromHome'] , 'EnvironmentSatisfaction': b['EnvironmentSatisfaction'],
                   'HourlyRate':b['HourlyRate'],'JobInvolvement': b['JobInvolvement'],
                   'JobLevel': b['JobLevel'],'JobSatisfaction' :b['JobSatisfaction'],
                   'MonthlyIncome': b['MonthlyIncome'], 'MonthlyRate' :b['MonthlyRate'],
                   'NumCompaniesWorked': b['NumCompaniesWorked'],'PercentSalaryHike' :b['PercentSalaryHike'],
                   'RelationshipSatisfaction': b['RelationshipSatisfaction'],'StandardHours' :b['StandardHours'],
                   'TotalWorkingYears': b['TotalWorkingYears'],'TrainingTimesLastYear' :b['TrainingTimesLastYear'],
                   'YearsAtCompany': b['YearsAtCompany'],'YearsInCurrentRole' :b['YearsInCurrentRole'],
                   'YearsSinceLastPromotion': b['YearsSinceLastPromotion'],'YearsWithCurrManager' :b['YearsWithCurrManager'],
                   'MaritalStatus_': b['MaritalStatus_'],'JobRole_' :b['JobRole_'],
                   'Gender_': b['Gender_'],'EducationField_' :b['EducationField_'],
                   'Department_': b['Department_'],'BusinessTravel_' :b['BusinessTravel_'],
                   'OverTime_': b['OverTime_'],'Over18_' :b['Over18_'],
                   'empName': b['empName'],'empID' :b['empID'],
                   'PerformanceScore': b['PerformanceScore'],
                   'id': str(b['_id']) })

    return Response(json.dumps(documents_), mimetype='application/json')