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E11000 duplicate key error index in mongodb mongoose
... null value.
In other words, a sparse index is ok with multiple documents all having null values.
sparse indexes
From comments:
Your error says that the key is named mydb.users.$email_1 which makes me suspect that you have an index on both users.email and users.local.email (The former being old an...
Android: how do I check if activity is running?
... activities that link to each other then onStop on the first is sometimes called after onStart in second. So both might be true briefly.
Depending on what you are trying to do (update the current activity from a service?). You could just register a static listener in the service in your activity on...
Git: “Not currently on any branch.” Is there an easy way to get back on a branch, while keeping the
... hash of last commit. Checkout the branch you wish to be at, and git merge _hash_
– Daniel
May 31 '12 at 13:31
BE REAL...
“for line in…” results in UnicodeDecodeError: 'utf-8' codec can't decode byte
... The trick is that ISO-8859-1 or Latin_1 is 8 bit character sets, thus all garbage has a valid value. Perhaps not useable, but if you want to ignore!
– Kjeld Flarup
Apr 12 '18 at 8:53
...
When should I use Struct vs. OpenStruct?
...
@IvanKolmychek: Cool, actually I prefer the block approach.
– tokland
Mar 9 '16 at 18:21
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Idiomatic way to convert an InputStream to a String in Scala
...uch the same thing. Not sure why you want to get lines and then glue them all back together, though. If you can assume the stream's nonblocking, you could just use .available, read the whole thing into a byte array, and create a string from that directly.
...
Where can I view Tomcat log files in Eclipse?
... "Arguments" tab of its launch configuration:
-Dcatalina.base="${project_loc}\<apache-tomcat-5.5.23_loc>"
-Dcatalina.home="${project_loc}\<apache-tomcat-5.5.23_loc>"
-Djava.util.logging.config.file="${project_loc}\<apache-tomcat-5.5.23_loc>\conf\logging.properties"
-Djava.uti...
What is the difference between a.getClass() and A.class in Java?
...getClass() will return the B class.
A.class evaluates to the A class statically, and is used for other purposes often related to reflection.
In terms of performance, there may be a measurable difference, but I won't say anything about it because in the end it is JVM and/or compiler dependent.
T...
What does a Ajax call response like 'for (;;); { json data }' mean? [duplicate]
I found this kind of syntax being used on Facebook for Ajax calls. I'm confused on the for (;;); part in the beginning of response. What is it used for?
...
Sending message through WhatsApp
...en/android/26000030/?category=5245251
WhatsApp's Click to Chat feature allows you to begin a chat with
someone without having their phone number saved in your phone's
address book. As long as you know this person’s phone number, you can
create a link that will allow you to start a chat w...