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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...
Get the (last part of) current directory name in C#
...the last part of current directory, for example from /Users/smcho/filegen_from_directory/AIRPassthrough , I need to get AIRPassthrough .
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Remove Object from Array using JavaScript
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This however will remove all the occurrences found, not only the first one
– Flavien Volken
Jul 12 '16 at 6:49
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Apply CSS style attribute dynamically in Angular JS
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ngStyle directive allows you to set CSS style on an HTML element dynamically.
Expression which evals to an object whose keys are CSS style names and values are corresponding values for those CSS keys. Since some CSS style names are not val...
How get integer value from a enum in Rails?
...t the integer values for an enum from the class the enum is on:
Model.sale_infos # Pluralized version of the enum attribute name
That returns a hash like:
{ "plan_1" => 1, "plan_2" => 2 ... }
You can then use the sale_info value from an instance of the Model class to access the integer v...
Replacing all non-alphanumeric characters with empty strings
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Use [^A-Za-z0-9].
Note: removed the space since that is not typically considered alphanumeric.
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How do you create a Swift Date object?
... dateFromString. If you wanted to return a nil on bad parses, you would ideally use a failible initializer; but you cannot do that now (June 2015), because of a limitation in Swift 1.2, so then you're next best choice is to use a class factory method.
A more elaborate example, which addresses both ...
iPhone App 开发第一步：从零到真机调试HelloWorld - 更多技术 - 清泛网 - ...
...机器（intel已经可以装lion了，此处不再讨论），应用darwin_snow_legacy.iso，进行引导，之后一路安装直至成功；
（2）安装完成后，装VMTools实现共享，以及声卡驱动；（3）之后要对系统进行升级（我是从10.6升级至10.6.7），升...
get size of json object
... check the size i.e. like that:
var data = {one : 1, two : 2, three : 3};
_.size(data);
//=> 3
_.keys(data);
//=> ["one", "two", "three"]
_.keys(data).length;
//=> 3
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Using CookieContainer with WebClient class
... limited functionalty. Before I knew about this option, I wrote lots of really painful code at the HttpWebRequest layer because WebClient almost, but not quite, did what I needed. Derivation is much easier.
Another option is to use the regular WebClient class, but manually populate the Cookie he...