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How to access component methods from “outside” in ReactJS?
...t;
</div>
);
}
}
Note: This will only work if the child component is declared as a class, as per documentation found here: https://facebook.github.io/react/docs/refs-and-the-dom.html#adding-a-ref-to-a-class-component
Update 2019-04-01: Changed example to use a class ...
Loop backwards using indices in Python?
...
the second argument is one less than the final value. so if you put -1 then the range stops at 0, if you put -5, the range stops at -4 (for an increment of -1)
– mulllhausen
Jul 20 '14 at 14:01
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Node.js, can't open files. Error: ENOENT, stat './path/to/file'
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Paths specified with a . are relative to the current working directory, not relative to the script file. So the file might be found if you run node app.js but not if you run node folder/app.js. The only exception to this is require('....
ModelSerializer using model property
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One note: The fields list in Meta is optional. If you omit fields, in the above example, you would get all the MyModel fields plus ext_link in the serialized data. And this is really awesome for complex models! EDIT: At least, this is true for djangorestframework==2.3.14....
常用Sql - 爬虫/数据库 - 清泛IT社区，为创新赋能！
本帖最后由 zqp2013 于 2015-3-17 22:06 编辑
mysql：drop table if exists tablename;
不能写成
drop table tablename if exists tablename;
mysql：建立索引Sql
CREATE TABLE tablename (
`ID` &nbs...
ObservableCollection not noticing when Item in it changes (even with INotifyPropertyChanged)
...Changed;
}
public void ContentCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
//This will get called when the collection is changed
}
}
Okay, that's twice today I've been bitten by the MSDN documentation being wrong. In the link I gave you it says:...
Hidden Features of Java
...d it, never heard of it before.
ThreadLocals are typically not so widely known as a way to store per-thread state.
Since JDK 1.5 Java has had extremely well implemented and robust concurrency tools beyond just locks, they live in java.util.concurrent and a specifically interesting example is the j...
ASP.NET MVC: No parameterless constructor defined for this object
... only have this problem (no parameterless bla bla...) during serialization if I define a constructor, and not a parameterless contructor. I mean, in this example, if you delete the constructor you defined ( public MyModel(IHelper helper) {} ) the problem disappears... so everytime you create a const...
PSQLException: current transaction is aborted, commands ignored until end of transaction block
...tarted using Postgres... it's really annoying that Postgres does this, and now we have to be really rewrite a big bulk of our program that we are porting from Oracle to Postgres. Why isn't there an option like the first to make it behave like Oracle but without the auto-commit?
...
How to redirect to a 404 in Rails?
...self, there's no reason to; Rails has this functionality built in already. If you want to show a 404 page, create a render_404 method (or not_found as I called it) in ApplicationController like this:
def not_found
raise ActionController::RoutingError.new('Not Found')
end
Rails also handles Abs...