Question

在Android中使用Firestore，是否可以读取下面的嵌套对象“项”中的键？

{
    "email":"someemail@someaddress.com",
    "items": {
      "8G9RiMgx9SmDLYrQbNrN": true,
      "K19RiMr7SmDLYrQbNrN": true
    }
}

Answer 1

可以。试试下面的代码吧：

JSONObject data = new JSONObject("youJson");
data = data.optJSONObject("items");
Iterator<String> iter = data.keys();

//Iterate all the keys
while (iter.hasNext()) { 
    String key = iter.next();
    Boolean value = json.optBoolean(key); //Get the actual value 
}

Answer 2

如果您有一个表示该JSON结构的Firestore DocumentSnapshot，则可以使用以下命令获取项的密钥：

from flask import current_app, request
from six.moves.urllib.parse import urlsplit

def endpoint_for(url, method=None, return_rule=False, follow_redirects=True):
    """
    Given an absolute URL, retrieve the matching endpoint name (or rule).
    Requires a current request context to determine runtime environment.

    :param str method: HTTP method to use (defaults to GET)
    :param bool return_rule: Return the URL rule instead of the endpoint name
    :param bool follow_redirects: Follow redirects to final endpoint
    :return: Endpoint name or URL rule, or `None` if not found
    """
    parsed_url = urlsplit(url)
    if not parsed_url.netloc:
        # We require an absolute URL
        return

    # Take the current runtime environment...
    environ = dict(request.environ)
    # ...but replace the HTTP host with the URL's host...
    environ['HTTP_HOST'] = parsed_url.netloc
    # ...and the path with the URL's path (after discounting the app path, if not hosted at root).
    environ['PATH_INFO'] = parsed_url.path[len(environ['SCRIPT_NAME']):]
    # Create a new request with this environment...
    url_request = current_app.request_class(environ)
    # ...and a URL adapter with the new request.
    url_adapter = current_app.create_url_adapter(url_request)

    # Domain or subdomain must match.
    # TODO: To support apps that host multiple domains, we need to remove this
    # check, or offer a callback hook to check the domain.
    if parsed_url.netloc != url_adapter.server_name and not (
            parsed_url.netloc.endswith('.' + url_adapter.server_name)):
        return

    try:
        endpoint_or_rule, view_args = url_adapter.match(parsed_url.path, method, return_rule=return_rule)
        return endpoint_or_rule
    except RequestRedirect as r:
        # A redirect typically implies `/folder` -> `/folder/`
        # This will not be a redirect response from a view, since the view isn't being called
        if follow_redirects:
            return endpoint_for(r.new_url, method=method, return_rule=return_rule, follow_redirects=follow_redirects)
    except HTTPException as e:
        pass
    # If we got here, no endpoint was found.

Answer 3

您可以这样迭代map来实现此目的：

yourRef.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
    @Override
    public void onComplete(@NonNull Task<QuerySnapshot> task) {
        if (task.isSuccessful()) {
            for (DocumentSnapshot document : task.getResult()) {
                Map<String, Object> items = (Map<String, Object>) document.get("items");
                for (Map.Entry<String, Object> entry : items.entrySet()) {
                    Log.d(TAG, entry.getKey() + "/" + entry.getValue());
                }
            }
        }
    }
});

Android-在嵌套对象Firestore中获取密钥

3 个答案: