[GitHub] jpkessle commented on a change in pull request #3244: Move parameter docs to separate page, add package params docs

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jpkessle commented on a change in pull request #3244: Move parameter docs to separate page, add package params docs
URL: https://github.com/apache/incubator-openwhisk/pull/3244#discussion_r165732819
 
 

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 File path: docs/parameters.md
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+# Working with parameters
+
+### Passing parameters to an action at invoke time
+
+Parameters can be passed to the action when it is invoked.  These examples use JavaScript but all the other languages work the same way.
+
+1. Use parameters in the action. For example, update the 'hello.js' file with the following content:
+
+  ```javascript
+  function main(params) {
+      return {payload:  'Hello, ' + params.name + ' from ' + params.place};
+  }
+  ```
+
+  The input parameters are passed as a JSON object parameter to the `main` function. Notice how the `name` and `place` parameters are retrieved from the `params` object in this example.
+
+2. Update the action so it is ready to use:
+
+  ```
+  wsk action update hello hello.js
+  ```
+
+3.  Parameters can be provided explicitly on the command-line, or by supplying a file containing the desired parameters
+
+  To pass parameters directly through the command-line, supply a key/value pair to the `--param` flag:
+  ```
+  wsk action invoke --result hello --param name Dorothy --param place Kansas
+  ```
+
+  In order to use a file containing parameter content, create a file containing the parameters in JSON format. The
+  filename must then be passed to the `param-file` flag:
+
+  Example parameter file called parameters.json:
+  ```json
+  {
+      "name": "Dorothy",
+      "place": "Kansas"
+  }
+  ```
+
+  ```
+  wsk action invoke --result hello --param-file parameters.json
+  ```
+
+  ```json
+  {
+      "payload": "Hello, Dorothy from Kansas"
+  }
+  ```
+
+  Notice the use of the `--result` option: it implies a blocking invocation where the CLI waits for the activation to complete and then
+  displays only the result. For convenience, this option may be used without `--blocking` which is automatically inferred.
+
+  Additionally, if parameter values specified on the command-line are valid JSON, then they will be parsed and sent to your action as a structured object. For example, if we update our hello action to:
+
+  ```javascript
+  function main(params) {
+      return {payload:  'Hello, ' + params.person.name + ' from ' + params.person.place};
+  }
+  ```
+
+  Now the action expects a single `person` parameter to have fields `name` and `place`. If we invoke the action with a single `person` parameter that is valid JSON:
+
+  ```
+  wsk action invoke --result hello -p person '{"name": "Dorothy", "place": "Kansas"}'
+  ```
+
+  The result is the same because the CLI automatically parses the `person` parameter value into the structured object that the action now expects:
+  ```json
+  {
+      "payload": "Hello, Dorothy from Kansas"
+  }
+  ```
+
+### Setting default parameters on an action
+
+Actions can be invoked with multiple named parameters. Recall that the `hello` action from the previous example expects two parameters: the *name* of a person, and the *place* where they're from.
+
+Rather than pass all the parameters to an action every time, you can bind certain parameters. The following example binds the *place* parameter so that the action defaults to the place "Kansas":
+
+1. Update the action by using the `--param` option to bind parameter values, or by passing a file that contains the parameters to `--param-file`
+
+  To specify default parameters explicitly on the command-line, provide a key/value pair to the `param` flag:
+
+  ```
+  wsk action update hello --param place Kansas
+  ```
+
+  Passing parameters from a file requires the creation of a file containing the desired content in JSON format.
+  The filename must then be passed to the `-param-file` flag:
+
+  Example parameter file called parameters.json:
 
 Review comment:
   Example parameter file called `parameters.json`:

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