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mongodb: insert if not exists
...u want to do an "upsert". MongoDB has built-in support for this. Pass an extra parameter to your update() call: {upsert:true}. For example:
key = {'key':'value'}
data = {'key2':'value2', 'key3':'value3'};
coll.update(key, data, upsert=True); #In python upsert must be passed as a keyword argumen...
Find the nth occurrence of substring in a string
...tive approach would be the usual way, I think.
Here's an alternative with string-splitting, which can often be useful for finding-related processes:
def findnth(haystack, needle, n):
parts= haystack.split(needle, n+1)
if len(parts)<=n+1:
return -1
return len(haystack)-len(pa...
Get the last non-empty cell in a column in Google Sheets
...
I ended up comparing with the empty string rather than using ISBLANK, which treats some empty-looking cells (e.g. blank-returning formulas like ="" as non-blank. Thus: '=index(filter(A:A, A:A<>""), rows(filter(A:A, A:A<>"")))'
...
Maven: How to include jars, which are not available in reps into a J2EE project?
... install:install-file -Dfile=cassandra-jdbc-1.1.1.jar -DgroupId=org.apache-extras.cassandra-jdbc -DartifactId=cassandra-jdbc -Dversion=1.1.1 -Dpackaging=jar"
– Mazrick
Jun 30 '12 at 3:14
...
How to use ScrollView in Android?
...on one of the views in the LinearLayout makes that view expand to fill any extra space.
Here is the XML
<?xml version="1.0" encoding="utf-8"?>
<ScrollView
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match...
Java8 Lambdas vs Anonymous classes
...s neat as compared to Anonymous Inner Class (AIC)
public static void main(String[] args) {
Runnable r = new Runnable() {
@Override
public void run() {
System.out.println("in run");
}
};
Thread t = new Thread(r);
t.start();
}
//syntax of lambda ...
Error message 'Unable to load one or more of the requested types. Retrieve the LoaderExceptions prop
...causes the error goes here.
}
catch (ReflectionTypeLoadException ex)
{
StringBuilder sb = new StringBuilder();
foreach (Exception exSub in ex.LoaderExceptions)
{
sb.AppendLine(exSub.Message);
FileNotFoundException exFileNotFound = exSub as FileNotFoundException;
i...
how to emulate “insert ignore” and “on duplicate key update” (sql merge) with postgresql?
...n.
You can of course wrap this in a function if you don't want to put the extra code on the client side. You also need a loop for the very rare race condition in that thinking.
There's an example of this in the documentation: http://www.postgresql.org/docs/9.3/static/plpgsql-control-structures.ht...
How to reverse a 'rails generate'
...y using the rails generate command.
For example:
rails g model Home name:string
creates a model named home with attribute name. To remove the files and code generated from that command we can use
rails d model Home
sh...
What is a good Hash Function?
...l, with an order of magnitude more collisions than we want. In particular, strings that differ only in the last 4 bytes can collide easily. If you have a 30 character string, that differ in the last 4 bytes, after 28 bytes have been processes, the hashes differ only in the last 2 bytes. That means y...