Request events.
 API Creator calls these for every request, after it receives the request but before it begins work. 
 
Response events.
 API Creator calls these for every request, before it sends back the (successful) final result to the client.

With your API open, in the Manage section, click 
Request Events
.
If you do not see this option, clear the 
Short Menu
 checkbox that appears below the menus.
Click 
Add
.
Complete the following fields on the page, and then save your changes:
 
Event type
 
The type of event.
 
Options:
 Request event or Response event
 
Event Handler name
 
The name for your event handler. API Creator invokes request and response events in alphabetical order based on their name.
You can have API Creator invoke your request and response events in a specific order by appending the event handler name with a number sequence.
 
Code
 
The handler operations for this event handler. For example:
if (“default/b2bderbypavlov/v1/SalesResports” == req.resourceName) {
  //log.debug(‘***SalesReports Req Event - json: ' + json);
  var data = JSON.parse(json); // json from the request
  var theOrder = data[0];
  var keptItemNum = 0;
  var keptItems = [];
  log.debug(“theOrder: " + JSON.stringify(theOrder));
  for ( var i = 0; i < theOrder.Order_DetailsList.length; i ++) {
      var eachItem = theOrder.Order_DetailsList(i);
      delete eachItem[“@metadata”];
      if (eachItem.SupplierName == “Pavlova, Ltd.”) {
         delete eachItem.OrderID;
         delete eachItem.ProductID;
...
 
Active
 
Indicates that this event handler is active. Select this checkbox.

API Creator performs initial authentication.
API Creator invokes the request event handler for every transaction, with the following variables pre-defined:
Variable Name	Description
json	The raw JSON string that the client sends, if any. Set only for POST and PUT requests. You can modify this string.
req	The request object.
log	The logger for the current request.
API Creator invokes request events in alphabetical order based on their name.
 You can have API Creator invoke your request events in a specific order by appending the event handler name with a number sequence.
API Creator establishes a connection to the database.
API Creator parses the JSON payload.

// Reject all requests on SecretData if they do not use HTTPS
if ("SecretData" == req.resourceName && !req.clientUsesHttps) {
  log.error('SecretData was accessed over HTTP by ' + req.clientAddress);
  throw "Use HTTPS to access this resource";
}

// Remove extraneous data that the client sends but that is not needed.
if ( ! json) {
  // Only requests with a JSON payload are needed.
  return;
}
var data = JSON.parse(json);
if (Array.isArray(data)) {
  for (var i = 0; i < data.length; i++) {
    delete data[i].uselessData;
  }
}
else {
  delete data.uselessData;
}
// Important: Serialize the data back to a string if you want to change it
json = JSON.stringify(data);

json

json

statusCode

txsummary

rulesummary

JSON.stringify()

getResource(resourceName, settings)

About resource object/attribute aliases matching partner expectations, see Logic Patterns.
About the LogicSample database, see Logic Sample Database.

// Remove all @metadata sections from the response for a specific table/resource
// Note: This would make it difficult for the client to update the data, but this is only an example.
// This only deals with top-level resources. To remove all
// @metadata sections from a complex resource, use recursion.
// An attribute 'TheVerb' is added to each array object or the single object
// with the name of request verb - GET, PUT, POST, PATCH, DELETE
// get the name used for metadata (configurable by project).
// You CAN convert from the Java string value to a JavaScript string object here
var metadataName = new String(req.metadata_name);
if (Array.isArray(json)) {
  // If the response is an array of objects
  for (var i = 0; i < json.length; i += 1) {
    delete json[i][metadataName];
    // You MUST convert to native JavaScript string
    json[i]['TheVerb'] = new String(req.verb.name());
  }
}
else {
  // The response is a single object
  delete json[metadataName];
  json['TheVerb'] = new String(req.verb.name());
}

amount_total

purchaseorders

// for a GET to an employee, add any PURCHASEORDERS where the employee is a sales rep
if ("GET" == req.verb && "employee" == req.resourceName && json.length) {
  for (var i = 0; i < json.length; i += 1) {
    // want purchase orders for this employee as sales rep
    // top thirty purchase orders by amount_total
    var detail = {
      filter: "salesrep_id = " + json[i].employee_id,
      order: "amount_total desc",
      pagesize: 30,
      offset: 0,
      verbose: false
    };
    var ordersAsSalesRep = getResource("purchaseorders", detail);
    json[i].ordersAsSalesRep = ordersAsSalesRep;
  }
}

// for a PUT (perhaps to update the name) of one or more employees
// add the picture into the result
if ("PUT" == req.verb && "employee" == req.resourceName) {
  var txsummary = json.txsummary;
  for (var i = 0, len = txsummary.length; i < len; i += 1) {
    var meta = txsummary[i]["@metadata"];
    if ("UPDATE" == meta.verb && "employee" == meta.resource) {
      var detail = { filter: "employee_id = " + summary[i].employee_id };
      var picInfo = getResource("employee_picture", detail);
      if (picInfo && picInfo.length > 0) {
        txsummary[i].the_picture = picInfo[0].picture;
      }
    }
  }
}

Create a new 

MyResource

 JavaScript resource defined as:

return { Happy: ['New', 'Year']};

In the REST Lab, view the result by performing a GET request, which is a different formatting of the previous JSON. Complete the following:

Make sure you are at least functioning by defining a simple response event. If the response event appears to be non-functional, check that it is configured as a response event and not as a REQUEST event:

// MUST be an object or an array, if not, it is coerced into one (and probably NOT what you want)
if ('GET' == req.verb.name && 'MyResource' == req.resourceName) {
  json = ["I got what I expected"];
}
else {
  // this is returned on ALL other requests, make sure you delete this !!!
  json = ["Not what I wanted"];
}

Change to a more specific handler without the else condition:

// Note double equals, as you are comparing JavaScript strings with java.lang.String objects
if ('GET' == req.verb.name && 'MyResource' == req.resourceName) {
  json = getResource('demo:customer');
}