Flask上的sqlalchemy.orm.exc.UnmappedInstanceError WTForm

Question

顯示相關表單時出現以下錯誤。

sqlalchemy.orm.exc.UnmappedInstanceError UnmappedInstanceError: Class 'sqlalchemy.util._collections.result' is not mapped

這裏是models.py

class Project(db.Model): 
__tablename__ = 'projects' 
id = db.Column(db.Integer, primary_key=True) 
title = db.Column(db.String(175), unique=True, nullable=False) 
description = db.Column(db.Text) 
#--------------------------- 
region = db.Column(db.Integer, db.ForeignKey('regions.id')) 
district = db.Column(db.Integer, db.ForeignKey('districts.id')) 
subdistrict = db.Column(db.Integer, db.ForeignKey('subdistricts.id')) 
village = db.Column(db.Integer, db.ForeignKey('villages.id')) 
#------------------------------------ 
baseline = db.Column(db.Text()) 
performance_indicator = db.Column(db.Text) 
budget = db.Column(db.Float()) 
author = db.Column(db.Integer, db.ForeignKey('users.id')) 
posted_date = db.Column(db.DateTime) 
start_date = db.Column(db.DateTime) 
est_completion = db.Column(db.DateTime) 
mark_complete = db.Column(db.Boolean, default=False) 
activities = db.relationship('Activity', backref='projects', cascade='all, delete-orphan', lazy='dynamic') 
remarks = db.relationship('Remark', backref='projects', cascade='all, delete-orphan', lazy='dynamic') 
beneficiary = db.Column(db.Integer, db.ForeignKey('beneficiaries.id')) 
sector = db.Column(db.Integer, db.ForeignKey('sectors.id')) 
media = db.relationship('Media', secondary=projects_media, backref='projects') 

def __init__(self, id, title, description, baseline, performance_indicator, budget, remark, remark_author, author, posted_date, start_date, est_completion, mark_complete): 
    self.id = id 
    self.title = title 
    self.description = description 
    self.baseline = baseline 
    self.performance_indicator = performance_indicator 
    self.budget = budget 
    self.author = author 
    self.posted_date = posted_date 
    self.start_date = start_date 
    self.est_completion = est_completion 
    self.mark_complete = mark_complete 

的forms.py

from flask.ext.wtf.file import FileRequired, FileAllowed, FileField 
from wtforms.ext.sqlalchemy.fields import QuerySelectField 
from project.location.models import Region, District, Subdistrict, Village 
from flask.ext.uploads import UploadSet, IMAGES, DOCUMENTS 
from flask_wtf import Form 
from wtforms.validators import DataRequired, NumberRange 
from . models import Sector, Project, Activity 
from project import db 
from project.crc.models import CrC 
from wtforms import StringField, TextAreaField, validators, SubmitField, SelectField, IntegerField, DateTimeField, \ 
RadioField, BooleanField, DecimalField, DateField, FileField 
def sector_lists(): 
    return db.session.query(Sector.name) 

def region_lists(): 
    return db.session.query(Region.region) 

def district_lists(): 
    return db.session.query(District.district) 

def sub_districts(): 
    return db.session.query(Subdistrict.subdistrict) 

def villages_lists(): 
    return db.session.query(Village.village) 

def project_lists(): 
    return db.session.query(Project.title) 

def activity_lists(): 
    return db.session.query(Activity.title) 

images = UploadSet('images', IMAGES) 


class ProjectForm(Form): 
    title = StringField('Project Name', validators=[DataRequired()]) 
    description = TextAreaField('Project Details', validators=[DataRequired()]) 
    sector = QuerySelectField(get_label='Service Sector', query_factory=sector_lists) 
    regions = QuerySelectField(get_label='Regions', query_factory=region_lists) 
    district = QuerySelectField(get_label='Regions', query_factory=district_lists) 
    subdistrict = QuerySelectField(get_label='Subdistrict', query_factory=sub_districts) 
    village = QuerySelectField(get_label='Village', query_factory=villages_lists) 
    baseline = TextAreaField('Baseline') 
    performance_indicator = TextAreaField('Performance Indicator') 
    budget = DecimalField("Planned Budget, places'2'") 
    started = DateTimeField('Project Started Date') 
    estimated_completion = DateField('Estimated Completion date', format='%Y-%m-%d') 
    completed = BooleanField('Completed?', default=False) 
    media_gallery = FileField('image', validators=[ 
    FileRequired(), 
    FileAllowed(images, "Image Only") 
]) 

最後我views.py

@app.route('/add', methods=['GET', 'POST']) 
def deliverables(): 
    forms = ProjectForm() 
    if request.method == 'POST' and forms.validate_on_submit(): 
     pmodel = Project(title=forms.title.data,description=forms.description.data, baseline=forms.baseline.data, performance_indicator=forms.performance_indicator.data, budget=forms.budget.data, author='mainuser', posted_date=datetime.datetime.utcnow(), start_date=forms.started.data, est_completion=forms.estimated_completion.data, mark_complete=forms.completed.data) 
    db.session.add(pmodel) 
    db.session.commit() 
return render_template('front/deliverables_edit.html', forms=forms) 

Answer 1

的query_factory callbac ķ應該返回完整實體，不列

def sector_lists(): 
    return db.session.query(Sector) 

def region_lists(): 
    return db.session.query(Region) 

def district_lists(): 
    return db.session.query(District) 

Answer 2

當你的代碼：

def sector_lists(): 
    return db.session.query(Sector.name) 

不能列返回QuerySelectField的query_factory（必須返回一個查詢），你已經在QuerySelectField的get_label規定：

sector = QuerySelectField(get_label='Service Sector',query_factory=sector_lists)

這就夠了。你必須改變功能sector_lists：

def sector_lists(): 
    return db.session.query(Sector)