以Python/Flask/SQLAlchemy的形式在两个db记录之间创建关系

我拼命地想做以下几件事：

以烧瓶形式捕捉2个人（即父亲和母亲）的详细信息。每个个体都是单个类/模型的实例，并存储在SQLAlchemy表中

当添加第二个个体（可以是父亲或母亲）时，将在Parents表中使用这两个个体的ID创建一个关系。这将在父亲和母亲之间创建一个关系记录。我很高兴一切都安排好了

主要应用程序代码如下。我想确保我可以同时获取两个id，以创建关系（因此打印语句）

然而，我第一次添加一个单独的、两个打印语句输出：

New father ID is 1

New mother ID is None  # this is probably expected as I haven't added the second Individual yet

第二次添加个人时，我得到：

New father ID is None

New mother ID is 2      # What has happened to the first Individual's ID?

我曾尝试声明全局变量以将ID写回，但在声明变量之前遇到了使用变量的错误

有人能帮忙吗

from genealogy import app
from flask import render_template, session, redirect, url_for, request
from genealogy import db
from genealogy.models import Individual, Parents
from genealogy.individual.forms import AddIndividual

@app.route("/", methods=["GET", "POST"])
def index():

    form = AddIndividual()

    def fullname(first, last):
        return first + " " + last

    if request.method == "POST":

        new_father = Individual("",None,None)
        new_mother = Individual("",None,None)
        new_child = Individual("",None,None)
        new_partners = Parents(None,None)

        if request.form.get("addfather") == "Add":
            father_forenames = form.father_forenames.data
            father_surname = form.father_surname.data
            father_fullname = fullname(father_forenames, father_surname)

            new_father = Individual(father_surname, father_fullname, father_forenames)
            db.session.add(new_father)
            session["new_father.id"] = new_father.id

            db.session.commit()
            # db.session.flush()

            # if Parents.query.filter_by(father_id=new_father.id, mother_id=new_mother.id):
            #     pass
            # else:
            #     new_partners = Parents(new_father.id, new_mother.id)
            #     db.session.add(new_partners)
            #     db.session.commit()

        if request.form.get("addmother") == "Add":
            mother_forenames = form.mother_forenames.data
            mother_surname = form.mother_surname.data
            mother_fullname = fullname(mother_forenames, mother_surname)

            new_mother = Individual(mother_surname, mother_fullname, mother_forenames)
            db.session.add(new_mother)
            session["new_mother.id"] = new_mother.id

            db.session.commit()
            # db.session.flush()

            # if Parents.query.filter_by(father_id=focus_father.id, mother_id=focus_mother.id):
            #     pass
            # else:
            #     new_partners = Parents(focus_father.id, focus_mother.id)
            #     db.session.add(new_partners)
            #     db.session.commit()

        if request.form.get("addchild") == "Add":
            child_forenames = form.child_forenames.data
            child_surname = form.child_surname.data
            child_fullname = fullname(child_forenames, child_surname)

            new_child = Individual(child_surname, child_fullname, child_forenames)
            db.session.add(new_child)
            focus_person = new_child

            db.session.commit()

        print("New father ID is " + str(session["new_father.id"]))
        print("New mother ID is " + str(session["new_mother.id"]))

        return render_template("home.html", form=form)

        # return render_template("home.html", form=form, focus_father=focus_father, focus_mother=focus_mother,
        #                        focus_person=focus_person, focus_partners=focus_partners)

    return render_template("home.html", form=form)

if __name__ == "__main__":
    app.run(debug=True)

---

感谢@van，以下是工作代码：

    from genealogy import app
    from flask import render_template, session, redirect, url_for, request
    from genealogy import db
    from genealogy.models import Individual, Parents
    from genealogy.individual.forms import AddIndividual
    
    @app.route("/", methods=["GET", "POST"])
    def index():
    
        form = AddIndividual()
    
        def fullname(first, last):
            return first + " " + last
    
        if request.method == "POST":
    
            new_father = Individual("",None,None)
            new_mother = Individual("",None,None)
            new_child = Individual("",None,None)
            new_partners = Parents(None,None)
    
            if request.form.get("addfather") == "Add":
                father_forenames = form.father_forenames.data
                father_surname = form.father_surname.data
                father_fullname = fullname(father_forenames, father_surname)
    
                new_father = Individual(father_surname, father_fullname, father_forenames)
                db.session.add(new_father)

    
                db.session.commit()
                db.session.flush()
                session["new_father.id"] = new_father.id

    
            if request.form.get("addmother") == "Add":
                mother_forenames = form.mother_forenames.data
                mother_surname = form.mother_surname.data
                mother_fullname = fullname(mother_forenames, mother_surname)
    
                new_mother = Individual(mother_surname, mother_fullname, mother_forenames)
                db.session.add(new_mother)

    
                db.session.commit()
                db.session.flush()
                session["new_mother.id"] = new_mother.id
    
    
            if request.form.get("addchild") == "Add":
                child_forenames = form.child_forenames.data
                child_surname = form.child_surname.data
                child_fullname = fullname(child_forenames, child_surname)
    
                new_child = Individual(child_surname, child_fullname, child_forenames)
                db.session.add(new_child)
                focus_person = new_child
    
                db.session.commit()
    
            print("New father ID is " + str(session["new_father.id"]))
            print("New mother ID is " + str(session["new_mother.id"]))
    
            return render_template("home.html", form=form)
    
            # return render_template("home.html", form=form, focus_father=focus_father, focus_mother=focus_mother,
            #                        focus_person=focus_person, focus_partners=focus_partners)
    
        return render_template("home.html", form=form)
    
    if __name__ == "__main__":
        app.run(debug=True)

---

您是否为每位家长提出单独的表格张贴请求？如果是，则很清楚为什么不保留

新父项

——它不会添加到会话中。在这种情况下，您应该将它添加到flask会话中，以便在请求之间保留它。谢谢您的回复。是的，我在父亲、母亲和孩子旁边有一个添加按钮。我对Flask比较陌生-我应该如何修改代码以将

new\u father

添加到会话中？那么您是否多次提交表单？每次对新的

个人
？是的，没错。因此，我输入父亲的名字，点击Add并将其保存为新的个人。然后我输入母亲的名字，点击Add并将她保存为新的个人。一旦创建了第二个表（无论哪种方式），我就想在一个单独的父表中创建与它们的关系（我知道怎么做）。它只是能够检测到我作为父亲添加的个人的ID。谢谢，请参阅官方文档。您只需将以前的对象添加到
会话中
，并在每个新的
帖子上检查它们。。。一经处理，立即进行清理<代码>会话['new\u father\u id']=new\u father.id
。并检查母亲：
如果会话中有“新父亲id:…
。