Understanding array.ForEach() Function with an Example

The example in this section illustrates an array, cakes.

Consider the example below which is available for you to experiment with at https://github.com/TIBCOSoftware/tci-flogo/tree/master/samples/app-dev/array.forEach.sample. 

{
   "cakes":[
      {
         "id":"0001",
         "type":"donut",
         "name":"Bundt Cake",
         "ppu":0.55,
         "batters":{
            "batter":[
               {
                  "id":"1001",
                  "type":"Regular"
               },
               {
                  "id":"1002",
                  "type":"Chocolate"
               },
               {
                  "id":"1003",
                  "type":"Blueberry"
               },
               {
                  "id":"1004",
                  "type":"Devil's Food"
               }
            ]
         },
         "topping":[
            {
               "id":"5001",
               "type":"None"
            },
            {
               "id":"5002",
               "type":"Glazed"
            },
            {
               "id":"5005",
               "type":"Sugar"
            },
            {
               "id":"5007",
               "type":"Powdered Sugar"
            },
            {
               "id":"5006",
               "type":"Chocolate with Sprinkles"
            },
            {
               "id":"5003",
               "type":"Chocolate"
            },
            {
               "id":"5004",
               "type":"Maple"
            }
         ]
      },
      {
         "id":"0002",
         "type":"Butter Cake",
         "name":"Raised",
         "ppu":0.55,
         "batters":{
            "batter":[
               {
                  "id":"1001",
                  "type":"Regular"
               }
            ]
         },
         "topping":[
            {
               "id":"5001",
               "type":"None"
            },
            {
               "id":"5002",
               "type":"Glazed"
            },
            {
               "id":"5005",
               "type":"Sugar"
            },
            {
               "id":"5003",
               "type":"Chocolate"
            },
            {
               "id":"5004",
               "type":"Maple"
            }
         ]
      },
      {
         "id":"0003",
         "type":"Biscuit Cake",
         "name":"Old Fashioned",
         "ppu":0.55,
         "batters":{
            "batter":[
               {
                  "id":"1001",
                  "type":"Regular"
               },
               {
                  "id":"1002",
                  "type":"Chocolate"
               }
            ]
         },
         "topping":[
            {
               "id":"5001",
               "type":"None"
            },
            {
               "id":"5002",
               "type":"Glazed"
            },
            {
               "id":"5003",
               "type":"Chocolate"
            },
            {
               "id":"5004",
               "type":"Maple"
            }
         ]
      }
   ]
}

In the above example, the cakes array has two nested arrays called topping and batter. You can use array.forEach() function to iterate the cakes array or you can also iterate its nested arrays, topping or batter while iterating the cakes array. Basically, you can iterate through nested arrays while iterating through the parent array.

The array.forEach() function can take three arguments:
  1. The first argument is the source array to iterate over
  2. The second argument is the scope, which typically consists of the array you are iterating over and so has the same name as that array
  3. The third optional argument is the condition to use to pull information when looping through the array.
For example, if you want to filter the cakes array based on type "donut", you would use the following expression: 
array.forEach($flow.body.cakes,"cakes",$loop.type=="donut")
where
  • $ flow.body.cakes is the source array to iterate over.
  • "cakes" is the scopeName. This is the scope for your mapping. Each scope has a name to it. By default, the scope name is the same as the name of the source array, in this case "cakes".

  • $loop.type=="donut" is the condition to filter the array elements.

The above example displays as follows in the mapper:

To filter the cakes array based on type "donut", you would use the following: 
array.forEach($flow.body.cakes,"cakes",$loop.type=="donut")
To filter the batter array inside cakes array based on its type "Regular", use: 
array.forEach($loop[cakes].batters.batter,"batter",$loop.type=="Regular")

Here, $loop[cakes] indicates that the cakes parent array is being iterated over and during each iteration of the cakes array, the batter array is also being iterated.

To filter the topping array inside cakes array based on its type "Powdered Sugar", use: 
 array.forEach($loop[cakes].topping,"topping",$loop.type=="Powdered Sugar")

Here, while iterating the cakes parent array, we are also iterating over the topping array.

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