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MongoDB: How to query for records where field is null or not set?
...ount({sent_at: {$exists: false}})
If its there and null, or not there at all:
db.emails.count({sent_at: null})
Refer here for querying and null
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You need to use a Theme.AppCompat theme (or descendant) with this activity
...a subclass, ActionBarActivity), to Activity, must also change the various calls with "support" to the corresponding call without "support". So, instead of getSupportFragmentManager, call getFragmentManager.
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How do I pass an object from one activity to another on Android? [duplicate]
...tom classes across activities. I have found this very useful.
Here is a small snippet of code I am using
CustomListing currentListing = new CustomListing();
Intent i = new Intent();
Bundle b = new Bundle();
b.putParcelable(Constants.CUSTOM_LISTING, currentListing);
i.putExtras(b);
i.setClass(this,...
What does the exclamation mark do before the function?
...s just a function declaration. You would need an invocation, foo(), to actually run the function.
Now, when we add the seemingly innocuous exclamation mark: !function foo() {} it turns it into an expression. It is now a function expression.
The ! alone doesn't invoke the function, of course, but w...
How to unsubscribe to a broadcast event in angularJS. How to remove function registered via $on
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You need to store the returned function and call it to unsubscribe from the event.
var deregisterListener = $scope.$on("onViewUpdated", callMe);
deregisterListener (); // this will deregister that listener
This is found in the source code :) at least in 1.0.4. I'll j...
How do I declare a namespace in JavaScript?
... This does not create a closure for your code - it makes it tedious to call your other functions because they always have to look like: yourNamespace.bar(); I made an open source project JUST to address this design problem: github.com/mckoss/namespace.
– mckoss
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How to define a two-dimensional array?
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You're technically trying to index an uninitialized array. You have to first initialize the outer list with lists before adding items; Python calls this
"list comprehension".
# Creates a list containing 5 lists, each of 8 items, all set t...
What does “The APR based Apache Tomcat Native library was not found” mean?
...ns exactly what it says: "The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path"
The library referred to is bundled into an OS specific dll (tcnative-1.dll) loaded via JNI. It allows tomcat to use OS functionali...
Can PostgreSQL index array columns?
... to this question in the documentation. If a column is an array type, will all the entered values be individually indexed?
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Check number of arguments passed to a Bash script
...nd regex matching.
The following example checks if arguments are valid. It allows a single argument or two.
[[ ($# -eq 1 || ($# -eq 2 && $2 == <glob pattern>)) && $1 =~ <regex pattern> ]]
For pure arithmetic expressions, using (( )) to some may still be better, but they ...