_cache (Scripting Object)

Description

The _cache object provides a way to store information at various points in a Merge run and retrieve it later on. The _cache data does not disappear between Merge events nor between Merge documents. Stored data is simply associated with a given name. _cache variables and their values are often defined via the -cache command line option. In JavaScript, you can assign a value to a cache variable either by directly assigning it to the variable as in:

_cache.foo = "some value";

or by using the _cache.set() function as in:

 _cache.set("foo", "some value");

Similarly, you can retrieve values from _cache by:

var value = _cache.foo;         // sets value to "some value"
var value2 = _cache.get("foo"); // sets value2 to "some value"

Embedded references can be made to _cache variables via the syntax [!Cache name], as in [!Cache foo] using the above example.

Note _cache variables are always stored as strings. A side effect of that is that the + operator in JavaScript implies concatenation, not addition. It's likely that you may want to make liberal use of the construct parseInt(_cache.name). _cache variables are often used in counting operations; if you use the standard JavaScript notation of ++ that is recognized as an integer operation and the _cache variable will be automatically converted to a number before being incremented and then stored back as a string.

_cache.counter = 0;  ...
_cache.counter++;

Advanced _cache usage

Sometimes you wish to cache arrays of values. There are various techniques that you could use. The following is a rarely used method. It's rare because people rarely use _cache.set("name") when they can simply use _cache.name. However, there is the further option of:

_cache.set("name", someValue, index);

which lets you supply an array index, hence permitting the creation of an array of values. Naturally, there is the corresponding:

_cache.get("name", index);

to retrieve an array element.

Functions

See Also

Auto/Embedded Fields
-cache - command-line option