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mongodb count num of distinct values per field/key
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MongoDB has a distinct command which returns an array of distinct values for a field; you can check the length of the array for a count.
There is a shell db.collection.distinct() helper as well:
> db.countries.distinct('country');
[ "Spain", "Engl...
@RequestBody and @ResponseBody annotations in Spring
Can someone explain the @RequestBody and @ResponseBody annotations in Spring 3? What are they for? Any examples would be great.
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Create a new Ruby on Rails application using MySQL instead of SQLite
...rails project, change the adapter in the config/database.yml file to mysql and make sure you specify a valid username and password, and optionally, a socket:
development:
adapter: mysql2
database: db_name_dev
username: koploper
password:
host: localhost
socket: /tmp/mysql.sock
Next, m...
optional local variables in rails partial templates: how do I get out of the (defined? foo) mess?
I've been a bad kid and used the following syntax in my partial templates to set default values for local variables if a value wasn't explicitly defined in the :locals hash when rendering the partial --
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What is a regular expression which will match a valid domain name without a subdomain?
...ote, to use this regex, you will need to convert the domain to lower case, and also use an IDN library to ensure you encode domain names to ACE (also known as "ASCII Compatible Encoding"). One good library is GNU-Libidn.
idn(1) is the command line interface to the internationalized domain name libr...
How does tuple comparison work in Python?
I have been reading the Core Python programming book, and the author shows an example like:
4 Answers
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Jackson - Deserialize using generic class
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You need to create a TypeReference object for each generic type you use and use that for deserialization. For example -
mapper.readValue(jsonString, new TypeReference<Data<String>>() {});
share
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Can't ignore UserInterfaceState.xcuserstate
...is currently tracked, use git rm --cached.
Use this, replacing [project] and [username] with your info:
git rm --cached [project].xcodeproj/project.xcworkspace/xcuserdata/[username].xcuserdatad/UserInterfaceState.xcuserstate
git commit -m "Removed file that shouldn't be tracked"
Alternatively y...
Java Keytool error after importing certificate , “keytool error: java.io.FileNotFoundException & Acc
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This could happen if you are not running the command prompt in administrator mode.
If you are using windows 7, you can go to run, type cmd and hit Ctrl+Shift+enter. This will open the command prompt in administrator mode. If not, you can also go to start -> all programs...
How to convert int to NSString?
...s with @() expression. So the shortest way is to transform int to NSNumber and pick up string representation with stringValue method:
NSString *strValue = [@(myInt) stringValue];
or
NSString *strValue = @(myInt).stringValue;
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