使用 AND 和 OR 动态连接 Django Q 对象

Posted 2023-02-23

【中文标题】使用 AND 和 OR 动态连接 Django Q 对象

【英文标题】：dynamically connecting Django Q objects with AND and OR

【发布时间】：2012-12-16 13:43:07

【问题描述】：

我希望用户能够通过几个不同的参数（姓名、年份等）查询我的数据库，动态添加更多字段，并使用布尔运算符将它们连接起来；最终结果将类似于“年份 = 1900 AND 名称 = 鸡 AND 位置 = 旧金山”。我认为我做错了什么，因为它没有返回任何内容，即使我只尝试一个我知道与某些数据匹配的值的字段（例如，当我从 Django shell 使用 .filter() 时，我可以取回对象）。有人知道我该如何解决吗？

相关视图（忽略草率的缩进，我不想通过并修复所有它，但它在我的实际代码中是正确的）：

class BaseSearchFormSet(BaseFormSet):
def clean(self):
    if any(self.errors):
        return self.errors
    queries = []
    valid_courses = ["appetizer","main","dessert"]
    valid_period = re.compile(r'\d\d\d0-\d\d\d5|\d\d\d5-\d\d\d0')
    valid_year = re.compile(r'\d4')
    multi_rows = ["year","period","course"]
    for x in xrange(0,self.total_form_count()):
        form = self.forms[x]
        query = form.cleaned_data.get("query")
        row = form.cleaned_data.get("row")
        if query in queries and row not in multi_rows:
            raise forms.ValidationError("You're already searching for %s.")
        queries.append(query)
        if row == "course" and query.lower() not in valid_courses:
            raise forms.ValidationError("%s is not a valid course option."%(form.cleaned_data["query"]))
        if row == "period" and not re.match(valid_period,query):
            raise forms.ValidationError("%s is not a properly formatted period. Valid five-year periods span either the first or second half of a decade. For example: 1910-1915, 1925-1930."%(form.cleaned_data["query"]))
        if row == "year" and not re.match(valid_year,query):
            raise forms.ValidationError("Please enter a four-digit year.")
def search(request):
errors = []
searchFormSet = formset_factory(F.SearchForm, extra=1,formset=BaseSearchFormSet)
if request.GET:
    formset = searchFormSet(request.GET)
    forms = []
    if formset.is_valid():
        for x in xrange(0,formset.total_form_count()):
            form = 
            form["row"]= formset[x].cleaned_data.get("row",None)
            form["query"] = formset[x].cleaned_data.get("query",None)
            form["bools"] = formset[x].cleaned_data.get("bools",None)
            if form["query"]:
                q = form["query"]
            else:
                errors.append("no query found")
            if form["row"]:
                row = form["row"]
            else:
                errors.append("no row found")
            filter_keys = "dish_name":Q(dish__name__icontains=q),
                "regex":Q(dish__full_name__regex=r'%s'%(q)),
                "course":Q(dish__classification=q.lower()),
                "year":Q(page__menu_id__year__exact=q),
                "period":Q(page__menu_id__period__exact=q),
                "location":Q(page__menu_id__location__icontains=q),
                "restaurant":Q(page__menu_id__restaurant__icontains=q)
            forms.append(form)
        final_query=Q()
        def var_reduce(op,slice):
            if op == "and":
                return reduce(lambda x,y: x & y,slice)
            elif op == "or":
                return reduce(lambda x,y: x | y,slice)
        for x in xrange(len(forms)):
            try:
                try:
                    if final_query:
                        slice = [final_query,filter_keys[forms[x]["row"]],filter_keys[forms[x+1]["row"]]]
                    else:
                        slice = [filter_keys[forms[x]["row"]],filter_keys[forms[x+1]["row"]]]
                    final_query = var_reduce(forms[x]["bools"],slice)
                except IndexError:
                    if final_query:
                        slice = [final_query,filter_keys[forms[x]["row"]]]
                    else:
                        slice = [filter_keys[forms[x]["row"]]]
                    final_query = var_reduce(forms[x]["bools"],slice)
                items = MenuItem.objects.filter(final_query)
                return render_to_response("search_results.html","items":items,"formset":formset)
            except KeyError as e:
                errors.append(e)    
                formset = searchFormSet(None)
                return render_to_response("search_page.html","errors":errors,"formset":formset)
    else:   
        formset = searchFormSet(None)
        return render_to_response("search_page.html","errors":errors,"formset":formset)
else:
    formset = searchFormSet(None)
    return render_to_response("search_page.html","formset":formset)

型号：

from django.db import models

class MenuItem(models.Model):
def format_price(self):
    return "$0:0<4,.2f".format(float(self.price))
def __unicode__(self):
    return self.dish
dish=models.OneToOneField('Dish',to_field='mk')
price=models.CharField(max_length=5,blank=True)
page=models.OneToOneField('MenuPage')
mk=models.CharField(max_length=10,unique=True)
formatted_price = property(format_price)
class Menu(models.Model):
def period(self):#adapted from http://***.com/questions/2272149/round-to-5or-other-number-in-python
    try:
        p=int(10*round(float(int(self.year))/10))
        if p < self.year:
            return "%s-%s"%(p,p+5)
        else:
            return "%s-%s"%(p-5,p)
    except (ValueError,TypeError):
        return ""
def __unicode__(self):
    if self.restaurant:
        return self.restaurant
    else:
        return self.mk
restaurant=models.TextField(unique=False,blank=True,null=True)
year=models.CharField(max_length=4,unique=False,blank=True,null=True)
location=models.TextField(unique=False,blank=True,null=True)
status=models.CharField(unique=False,max_length=20)
mk=models.CharField(max_length=8,unique=True,primary_key=True)
period=property(period) 
language = models.CharField(unique=False,max_length=30)
#objects=MenuManager()

class MenuPage(models.Model):
mk=models.CharField(max_length=10,unique=True)
menu_id=models.OneToOneField("Menu",to_field='mk')
#objects=MenuPageManager()
class Dish(models.Model):
def __unicode__(self):
    return self.name
full_name = models.TextField()
name=models.CharField(unique=True,max_length=255)
mk=models.CharField(max_length=10,unique=True)
class Classification(models.Model):
def __unicode__(self):
    if self.classification:
        return self.classification
    else:
        return "none"
dish=models.OneToOneField('dish',to_field='name')
classification=models.CharField(unique=False,max_length=9)
mk=models.CharField(max_length=10,primary_key=True)

我的搜索页面的html：

% extends "base.html" %
% block style %
<link rel="stylesheet" type="text/css" href="/static/search_style.css" />
% endblock %
% block java %
<script type="text/javascript" src="/static/searches.js"></script>
% endblock %
% block title %Search% endblock %
% block head %Search% endblock %
% block content %
% autoescape off %
<div id="searches">
<form id="search" action="" method="get">
    <table border="0" cellpadding="0" cellspace="0">
        <tbody class="search">
            % for form in formset.forms %
            <tr>
                <td class="row"> form.row </td>
                <td class="query"> form.query </td>
                <td class="bool"> form.bools </td>
            </tr>
        % endfor %
        </tbody>
    </table>
     formset.management_form 
    <input type="submit" value="Submit" id="submit">
</form>
</div>
% if formset.errors or errors %
<div id="errors">
<h3>The following errors were encountered while trying to submit your search:</h3>
% for x,y in formset.errors.items %
<p> x  :  y </p>
% endfor %
 errors 
</div>
% endif %
<div id="notes">
<p>Searching by dish names, locations, and restaurants is case-insensitive.</p>
<p>Searching by course uses  case-insensitive exact matching. Valid courses are Appetizer, Main, and Dessert.</p>
<p>Years should be entered YYYY. Five-year periods span either the first or second half of a decade, and should be entered YYYY-YYYY. Example valid five-year periods are 1900-1905, 1995-2000, etc.</p>
<p>Regular expression search follows mysql regular expression syntax, as described <a href="http://dev.mysql.com/doc/refman/5.1/en/regexp.html" target="_blank">here</a>.</p>
 </div>

% endautoescape %
<br /><br /><br /><br /> <br /><br /><br />
% endblock %

% block footer %
<div id="warning">
<p>NOTE: This site and the information it contains are still in development. Some information may be missing or inaccurate.</p>
</div>
<div class="credits">
    Created and maintained by <a href="/about#sam">Sam Raker</a> and <a href="/about#rachel">Rachel Rakov</a>
    <br />
    Data graciously provided by <a href="http://menus.nypl.org" target="_blank">What's on the Menu?</a>
</div>
% endblock %

【问题讨论】：

lambda x,y: x & y 是operator.and_。

【参考方案1】：

对不起，我原来的帖子超出了您的需要。澄清一下，您需要做的就是：

Q(year__icontains=year_input_variable) | Q(city__icontains=city_input_variable) & Q(name__icontains=name_input_variable)

将 & 用于和，|或。

我之前发布的内容是，如果查询包含多个单词，它会检查是否所有单词都使用 operator.and 匹配，或者是否有任何单词使用 operator 匹配。 或。

【讨论】：

我喜欢它，但我想做的是显示结果，例如，匹配城市和年份或名称，这在你的解决方案中是不可能的，我不'不思考。

使用 & 对比 | docs.djangoproject.com/en/dev/topics/db/queries/…