2022.2

Project Initialization

This Demo Project takes the user first through how to correctly run a small Project that outputs Array elements to the console by making sure all asynchronous Logic is completed. Then it demonstrates how one might do this with multiple files, using a Boolean check.

The Demo Project guide is broken up into two parts, with their corresponding subsections:

Part One

In traditional, text-based programming languages, there is a clear order of execution. Lines of code are generally executed from top-to-bottom.

As Incari has a non-linear execution of Logic, there is no implicit way to guarantee that certain entities will be initialized before you try and do something with them. This is especially problematic when:

  • Working with Events - Because Incari is event-driven and multiple Branches of Logic can listen for the same event. This means that you can’t know for sure which branch will be fired in what order.

  • Working with Asynchronous Nodes - For most cases, Incari waits for Nodes to be evaluated before moving on to the next operation. It also waits for an entire Branch of Logic to finish before moving to the next Branch. This is referred to as synchronous. There are some Nodes, however, that take longer than normal, and Incari will start executing other parts of the Logic while waiting for these asynchronous Nodes to finish what they’re doing.

To ensure that things like Variables are initialized via the Logic, before trying to access them, you need to create some additional Logic. This involves creating some additional checks to verify that the Project is in the state that you want it to be in, before trying to work with its data.

The Project

To demonstrate this issue, we have a simple Project, which loads a JSON file containing a single object. This object is an Array of fruit names:

{
  "fruits": [
    "apple",
    "banana",
    "orange",
    "pear",
    "grape",
    "strawberry",
    "watermelon",
    "cherry",
    "mango",
    "pineapple",
    "coconut",
    "papaya",
    "guava",
    "lemon",
    "lime"
  ]
}

There are 3 blocks in the Project tab of the Logic Editor:

  1. “Project Init” - Uses the built-in On Initialize Event in combination with a Custom Event, called Project Init.

  2. “Load fruits.json” - Loads our fruits.json file, uses JSON Parse to convert it to a Dictionary, gets the Array of fruit names, and then saves it to a Variable, called Fruits.

  3. “Get a fruit name” - Attempts to get the fruit name with the index 10 from the Fruits Variable and print it’s name to the Console.

The Problem

❌

Error: cannot get array element 10. Check if index is in array range.

When running the Project, we get an error in the Console. This is because Incari is unable to find anything at the index 10, since the length of the Array is empty. This is due to it not yet being initialized with the loaded data from the fruits.json file.

The Solution

To fix this issue, we can:

  1. Create a Boolean-type Variable called isFruitsLoaded, with the default value of false.

  2. After the Fruits Variable's value is assigned, set isFruitsLoaded to true.

  3. Create an Event Listener to listen for the Variable’s value changing.

  4. Create a Branch Node to check if isFruitsLoaded is true. If it is, continue with the Branch of Logic.

Now, when we run the Project, we get the expected output:

✅

coconut

Part Two

In the previous example, we discussed how to manually check that a specific branch of asynchronous Logic has been completed, before trying to use any data generated or loaded by it. There are often cases, though, where you need to ensure that multiple criteria are met before the Project is classified as “initialized”.

In that case, we need to:

  • Create a Boolean Variable for each check

  • Create another Boolean that ensures all other checks are true.

The Other File

To illustrate the new use case, we have added an additional file, called vegetables.json, which contains a single object, called vegetables:

{
  "vegetables": [
    "carrot",
    "potato",
    "tomato",
    "cucumber",
    "onion",
    "pepper",
    "celery",
    "garlic",
    "ginger",
    "sweet potato",
    "pumpkin",
    "cauliflower",
    "artichoke",
    "asparagus",
    "eggplant",
    "okra",
    "zucchini",
    "brussel sprout",
    "cabbage",
    "lettuce",
    "spinach",
    "kale",
    "broccoli",
    "collard green",
    "radish",
    "pea",
    "bell pepper",
    "parsnip",
    "spring onion",
    "mushroom",
    "beet",
    "sweetcorn"
  ]
}

To load the JSON, we do the same as before, but change the:

  1. File Attribute of the Load File Node.

  2. Key Attribute of the Get Dictionary Element Node.

  3. The Array Variable that is set to a new one named isVegetablesLoaded.

Checking if ALL JSON Files are loaded

Because we now need to check that both the Vegetables and Fruits Arrays are loaded, we need to do things a little bit differently. Before, we could plug the onChange Events directly into our other Logic. Now, however, we need an additional Boolean, which we will call isJSONLoaded. We then need to utilize the AND Node, which returns true if all of its inputs are also true.

The Event Listener

Now that we have our additional checks, we can listen for the isJSONLoaded Variable being changed, so that we can access both our Vegetables and Fruits Arrays and be sure that they have been populated with the values from the JSON files.

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