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Rails Migration: Remove constraint
I have a table in a Rails application which (in schema.rb) looks like:
2 Answers
2
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What is the purpose of the word 'self'?
...way that makes the instance to which the method belongs be passed automatically, but not received automatically: the first parameter of methods is the instance the method is called on. That makes methods entirely the same as functions, and leaves the actual name to use up to you (although self is th...
Python 2.7: Print to File
...
In Python 3.0+, print is a function, which you'd call with print(...). In earlier version, print is a statement, which you'd make with print ....
To print to a file in Python earlier than 3.0, you'd do:
print >> f, 'what ever %d', i
The >> operator directs pr...
remove objects from array by object property
...e.indexOf(obj.id) !== -1) {
arrayOfObjects.splice(i, 1);
}
}
All you need to do to fix the bug is decrement i for the next time around, then (and looping backwards is also an option):
for (var i = 0; i < arrayOfObjects.length; i++) {
var obj = arrayOfObjects[i];
if (listTo...
Server.Transfer Vs. Response.Redirect
... pages which resides on different server and domain.
Below is a summary table of which chalks out differences and in which scenario to use.
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Adding a cross-reference to a subheading or anchor in another page
... because it works across files, when section headings are changed, and for all builders that support cross-references.
RST, in General
The tools that convert RST files to HTML do not necessarily have a notion of collection. This is the case for instance if you rely on github to convert RST files ...
Simple Vim commands you wish you'd known earlier [closed]
... this list is nice, but I really want to know how did you draw this table? with VIM? which plugin? I'm looking for one currently.
– Kent
Mar 11 '10 at 14:34
6
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What does `:_*` (colon underscore star) do in Scala?
...tes: MetaData, scope: NamespaceBinding,
child: Node*)
which is called as
new Elem(prefix, label, attributes, scope,
child1, child2, ... childN)
but here there is only a sequence, not child1, child2, etc. so this allows the result sequence to be used as the input to the constru...
Django set default form values
...ch is explained here
You have two options either populate the value when calling form constructor:
form = JournalForm(initial={'tank': 123})
or set the value in the form definition:
tank = forms.IntegerField(widget=forms.HiddenInput(), initial=123)
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How to tell if a tag failed to load
I'm dynamically adding <script> tags to a page's <head> , and I'd like to be able to tell whether the loading failed in some way -- a 404, a script error in the loaded script, whatever.
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