大约有 44,000 项符合查询结果（耗时：0.0669秒） [XML]
Mongo: find items that don't have a certain field
...e using $exists:
db.things.find( { a : { $exists : false } } ); // return if a is missing
When is true, $exists matches the documents that contain the field, including documents where the field value is null. If is false, the query returns only the documents that do not contain the field.
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.rar, .zip files MIME Type
...zip
I would do a check on the file name too. Here is how you could check if the file is a RAR or ZIP file. I tested it by creating a quick command line application.
<?php
if (isRarOrZip($argv[1])) {
echo 'It is probably a RAR or ZIP file.';
} else {
echo 'It is probably not a RAR or Z...
What's the difference between BaseAdapter and ArrayAdapter?
I want to know the difference between using BaseAdapter and ArrayAdapter .
6 Answers
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Export query result to .csv file in SQL Server 2008
...comma-delimited text.
To save the results of a query to a file: Ctrl + Shift + F
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How to make a class JSON serializable
... "/foo/bar"}'
In that case you can merely call json.dumps(f.__dict__).
If you want more customized output then you will have to subclass JSONEncoder and implement your own custom serialization.
For a trivial example, see below.
>>> from json import JSONEncoder
>>> class MyEn...
When to use generic methods and when to use wild-card?
...t there are also certain places, where you have to use type parameters.
If you want to enforce some relationship on the different types of method arguments, you can't do that with wildcards, you have to use type parameters.
Taking your method as example, suppose you want to ensure that the src...
UIScrollView scroll to bottom programmatically
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It wil not work properly if contentSize is lower than bounds. So it should be like this: scrollView.setContentOffset(CGPointMake(0, max(scrollView.contentSize.height - scrollView.bounds.size.height, 0) ), animated: true)
– Bart...
How to change the style of alert box?
... functionality.
var ALERT_TITLE = "Oops!";
var ALERT_BUTTON_TEXT = "Ok";
if(document.getElementById) {
window.alert = function(txt) {
createCustomAlert(txt);
}
}
function createCustomAlert(txt) {
d = document;
if(d.getElementById("modalContainer")) return;
mObj = d.g...
How to express a NOT IN query with ActiveRecord/Rails?
Just to update this since it seems a lot of people come to this, if you are using Rails 4 look at the answers by Trung Lê` and VinniVidiVicci.
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“SetPropertiesRule” warning message when starting Tomcat from Eclipse [duplicate]
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Correct answer, never 'ignore' warnings if at all possible. Ignore enough warnings, some day they'll cause you to miss a REAL problem.
– Manius
Oct 18 '10 at 1:38
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