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new ef1627e Add example for dynamic combinator (#62)
ef1627e is described below
commit ef1627e1bdb73b8c3a9999e51418153e37670830
Author: Olivier Tardieu <[email protected]>
AuthorDate: Tue Dec 10 16:28:15 2019 -0500
Add example for dynamic combinator (#62)
This example illustrates how to invoke an action from the current package
(the package containing the composition).
---
docs/COMBINATORS.md | 32 +++++++++++++++++++++++++++++++-
1 file changed, 31 insertions(+), 1 deletion(-)
diff --git a/docs/COMBINATORS.md b/docs/COMBINATORS.md
index 1294944..44cebb6 100644
--- a/docs/COMBINATORS.md
+++ b/docs/COMBINATORS.md
@@ -69,10 +69,14 @@ assumed.
Examples:
```javascript
-composer.action('hello')
+composer.action('hello') // default package
composer.action('myPackage/myAction')
composer.action('/whisk.system/utils/echo')
```
+To be clear, if no package is specified, the default package is assumed even if
+the composition itself is not deployed to the default package. To invoke an
+action from the same package as the composition the [`dynamic`](#dynamic)
+combinator may be used as illustrated [below](#example).
### Action definition
@@ -532,3 +536,29 @@ Other fields of the input parameter object are ignored.
The `dynamic` combinator invokes the action named _name_ with the input
parameter object _params_. The output parameter object for the composition is
the output parameter object of the action invocation.
+
+### Example
+
+The `dynamic` combinator may be used for example to invoke an action that
+belongs to the same package as the composition, without having to specify the
+package name beforehand.
+
+```javascript
+const composer = require('openwhisk-composer')
+
+function invoke (actionShortName) {
+ return composer.let(
+ { actionShortName },
+ params => ({ type: 'action', params, name:
process.env.__OW_ACTION_NAME.split('/').slice(0,
-1).concat(actionShortName).join('/') }),
+ composer.dynamic())
+}
+
+module.exports = composer.seq(
+ composer.action('echo'), // echo action from the default package
+ invoke('echo') // echo action from the same package as the
composition
+)
+```
+In this example, `let` captures the target action short name at compile time
+without expanding it to a fully qualified name. Then, at run time, the package
+name is obtained from the environment variable `__OW_ACTION_NAME` and combined
+with the action short name. Finally, `dynamic` is used to invoke the action.
