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How do you query for “is not null” in Mongo?
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This will return all documents with a key called "IMAGE URL", but they may still have a null value.
db.mycollection.find({"IMAGE URL":{$exists:true}});
This will return all documents with both a key called "IMAGE URL" and a non-null value.
d...
Installing Google Protocol Buffers on mac
I would like to install the older version of Google Protocol Buffers (protobuf-2.4.1) on mac using Terminal command line. I tried with brew install protobuf , but the latest version 2.5.0 has been installed. Is it possible to install the older version from terminal.
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How to Update Multiple Array Elements in mongodb
...At this moment it is not possible to use the positional operator to update all items in an array. See JIRA http://jira.mongodb.org/browse/SERVER-1243
As a work around you can:
Update each item individually
(events.0.handled events.1.handled
...) or...
Read the document, do the edits
manually and ...
Naming convention - underscore in C++ and C# variables
... in a class field. What does the underscore mean? Is there a reference for all these special naming conventions?
19 Answers...
What is the best method to merge two PHP objects?
...bj_merged = (object) array_merge((array) $obj1, (array) $obj2);
This actually also works when objects have methods. (tested with PHP 5.3 and 5.6)
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What is the JSF resource library for and how should it be used?
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Actually, all of those examples on the web wherein the common content/file type like "js", "css", "img", etc is been used as library name are misleading.
Real world examples
To start, let's look at how existing JSF implementati...
Javascript/DOM: How to remove all events of a DOM object?
Just question: Is there any way to completely remove all events of an object, e.g. a div?
12 Answers
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How to set child process' environment variable in Makefile
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I have GNU make 3.81, and all: <\n\t>export PROJ_ROOT=$(CURDIR)<\n\t>echo $(PROJ_ROOT)<\n> outputs the correct expansion for the first row, but only echo for the second one. PROJ_ROOT is not set after running make. Spaces around = gi...
Why is it slower to iterate over a small string than a small list?
...nd with timeit and noticed that doing a simple list comprehension over a small string took longer than doing the same operation on a list of small single character strings. Any explanation? It's almost 1.35 times as much time.
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Can modules have properties the same way that objects can?
...s? When I put this code in one file x.py and import it from another, then calling x.y results in AttributeError: 'NoneType' object has no attribute 'c', since _M somehow has value None...
– Stephan202
May 19 '09 at 1:35
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