Create or Modify Counters
-
Use the
CountersFor.Increment
method to create a new Counter or modify an existing Counter's value. -
If the Counter exists,
Increment
will add the specified number to the Counter's current value.
If the Counter doesn't exist,Increment
will create it and set its initial value. -
For all other
CountersFor
methods see this Overview. -
In this page:
Increment
usage
Flow:
- Open a session.
-
Create an instance of
CountersFor
.- Either pass
CountersFor
an explicit document ID, -or- - Pass it an entity tracked by the session, e.g. a document object returned from session.Query or from session.Load.
- Either pass
- Call
CountersFor.Increment
. - Call
session.SaveChanges
for the changes to take effect.
Note:
- Modifying a Counter using
Increment
only takes effect whensession.SaveChanges()
is executed. - To decrease a Counter's value, pass the method a negative number to the
Increment
method.
Example
// Open a session
using (var session = docStore.OpenSession())
{
// Pass CountersFor's constructor a document ID
var documentCounters = session.CountersFor("products/1-A");
// Use `CountersFor.Increment`:
// ============================
// Increase "ProductLikes" by 1, or create it if doesn't exist with a value of 1
documentCounters.Increment("ProductLikes");
// Increase "ProductPageViews" by 15, or create it if doesn't exist with a value of 15
documentCounters.Increment("ProductPageViews", 15);
// Decrease "DaysLeftForSale" by 10, or create it if doesn't exist with a value of -10
documentCounters.Increment("DaysLeftForSale", -10);
// Execute all changes by calling SaveChanges
session.SaveChanges();
}
Syntax
void Increment(string counterName, long delta = 1);
Parameter | Type | Description |
---|---|---|
counterName |
string | Counter's name |
delta |
long | Increase Counter by this value. Default value is 1. For a new Counter, this number will be its initial value. |