python - 获取父表及其子表的正确方法

Question

我在父表和子表上有一对多关系。并尝试以 json 形式获取父表及其子表。

我尝试了如下所示的方法。

if (request.method == "GET"):   

    parents = Parent.objects.all()
    datas = []
    childTables = []
    for parent in parents:

        #fetching parent first and creating DICT for json
        #also creating an array for the child tables

        parentDict = {
            "id": parent.id,
            "project_name": parent.project_name,
            childTables: childTables,
        }

        #then fetching child tables NO problem at this part as well.
        childs = parent.child_set.filter(parent_id=parent)
        for child in childs:
            #creating a DICT FOR THE json.
            childDict = {
                "id":child.id,
                "ad_kind":child.ad_kind,
                "parent_id":child.parent_id,
            }

            #i am trying to append project's childs into ParentDict 
            #but still it's appending all childs into every ParentDict...
            #not just its parent's childs.
            parentDict["childTables"].append(childDict)


        #at last append all parent table inside an array and send it as JSON. 
        datas.append(parentDict)

    return JsonResponse(datas, safe=False)

当我尝试在其父字典中附加子表时，问题就开始了。但在上面的方式中，我只是将所有子项附加到每个父项字典中......

还有其他更简单的方法可以实现这一点吗？

Answer 1

问题出在您的 childTables 数组上。您应该将其放入父循环中，如果这样做，它将在每个循环上更新。然后就可以得到预期的结果了。

for parent in parents:

    #childTable array placed in here.
    #to renew on each loop.
    childTable = []

    parentDict = {
        "id": parent.id,
        "project_name": parent.project_name,
        childTables: childTables,
    }

    #... the rest is fine.