python - Using keys properly in a Mongo DB collection -


i have collection, each entry consists of fields 'a', 'b', 'c', 'd'.

i have combination of 'a' , 'b' serving key.

in other words, every combination of 'a' , 'b' must unique.

for purpose, using ensure_index method:

import pymongo client = pymongo.mongoclient(my_server_uri) collection = client[my_database_name][my_collection_name] collection.ensure_index([('a',pymongo.ascending),('b',pymongo.ascending)])

later in program, use find_one_and_replace method:

filter = {'a':a,'b':b} replacement = {'a':a,'b':b,'c':c,'d':d} collection.find_one_and_replace(filter,replacement,upsert=true)

this works fine, fail understand point in setting key , having specify again @ every update (i.e., calling ensure_index 'a' , 'b', , passing filter {'a':a,'b':b} on every call find_one_and_replace).

is there method can set key once, , later insert/update records without having specify fields part of key?

something like:

collection.ensure_index([('a',pymongo.ascending),('b',pymongo.ascending)]) record = {'a':a,'b':b,'c':c,'d':d} collection.insert_or_update(record)

the latest documentation suggests following methods, seem "suffer" same issue have described above:

  1. update (deprecated)
  2. find_and_modify (deprecated)
  3. update_one
  4. replace_one
  5. find_one_and_update
  6. find_one_and_replace

i think confusion here possibly stems "sql" perspective, happy sort of clarification.

thank you.

update

ok, think i've conceived @ least 1 insight 1 issue:

the method find_one_and_replace alone can used in order have combination of fields serving key. method ensure_index useful here improving performance. think (but i'm not sure) if using insert_one instead of find_one_and_replace, ensure_index useful preventing duplicate records.

is correct?


Comments

Post a Comment

Popular posts from this blog

PHP and MySQL WP -

i trying accomplish 2 things here code. writing php directly wp page using insert php plugin. 1) query mysql database , return results 1 column 4 columns. 2) make each result own hyperlink directs user new wp page runs new query on page. i able query show results , turn results dynamic hyperlink, cannot formatting down. right returns result 1 column. here have: [insert_php] $servername = "localhost"; $username = "login"; //edited privacy $password = "password"; //edited privacy $database = "database"; //edited privacy // create connection $conn = new mysqli($servername, $username, $password, $database); // check connection if ($conn->connect_error) { die("connection failed: " . $conn->connect_error); } echo "connected successfully"; //get results database $result = mysqli_query($conn,"select mine mines order mine"); $all_property = array(); //declare array saving property //showing proper...
Read more

android - InAppBilling registering BroadcastReceiver in AndroidManifest -

i'm implementing inapp billing in android app. works well, however, i'm trying decouple broadcast receiver activity manifest. suggestion in android's trivialdrive sample: // important: dynamically register broadcast messages updated purchases. // register receiver here instead of <receiver> in manifest // because call getpurchases() @ startup, therefore can ignore // broadcasts sent while app isn't running. // note: registering listener in activity bad idea, done here // because sample. regardless, receiver must registered after // iabhelper setup, before first call getpurchases(). currently there's class extends broadcastreceiver : public class iabbroadcastreceiver extends broadcastreceiver { /** * intent action receiver should filter for. */ public static final string action = "com.android.vending.billing.purchases_updated"; private final iabbroadcastlistener mlistener; public iabbroadcastreceiver(iabbroadcastlistener listener) { m...
Read more

nginx - phpPgAdmin - log in works but I have to login again after clicking on any links -

i have setup postgres 9.6 , phppgadmin on centos 7 server nginx, i can log in phppgadmin, postgresql server on right of page remains crossed out , link try browse (databases, roles etc) requires log in again. i'm thinking seems sessions problem, unsure how resolve it. any pointers on how fix or should looking @ in order track down problem? solved. turns out owner of /var/lib/php/session apache - needed nginx. sorted changing ownership nginx below: chown -r nginx:nginx /var/lib/php/session/
Read more