Game Foundation Tutorials

Playing with properties at runtime

In the previous tutorial, we learned how to configure mutable properties in the item definition.

In this one, we'll take a look at the code to get and modify the property of an item instance.

Prerequisites

We'll start from the end of the inventory tutorial. If you didn't follow this tutorial, please copy/paste the final source code in to a class file named GFInit.cs and associate it to a new GameObject of the new scene.

Checking the property existence for an item

Open your GFInit.cs file and replace OnInitSucceeded with the following code:

void OnInitSucceeded()
{
    Debug.Log("Game Foundation is successfully initialized");

    // Use the key you've used in the previous tutorial.
    const string definitionKey = "myFirstItem";

    // Finding a definition takes a non-null string parameter.
    InventoryItemDefinition definition = GameFoundationSdk.catalog.Find<InventoryItemDefinition>(definitionKey);

    // Make sure you retrieved a valid definition.
    if (definition is null)
    {
        Debug.Log($"Definition {definitionKey} not found");
        return;
    }

    // You should be able to get information from your definition now.
    Debug.Log($"Definition {definition.key} '{definition.displayName}' found.");

    InventoryItem item = GameFoundationSdk.inventory.CreateItem(definition);

    Debug.Log($"Item {item.id} of definition '{item.definition.key}' created");

    // This is the key of the property we've created
    const string propertyKey = "durability";

    // Check if the item has the property. Note that you can check
    // the property's existence on both the item and its definition.
    //bool hasProperty = definition.HasProperty(propertyKey);
    bool hasProperty = item.HasProperty(propertyKey);

    if (!hasProperty)
    {
        Debug.LogError($"Cannot find the property {propertyKey}");
        return;
    }

    Debug.Log($"Property '{propertyKey}' found");
}

Compile and start the scene. You should see the following log entry:

! Property 'durability' found

Getting the property's default value

You can retrieve the default value of a property within an item definition as following. Back to your code, append the follow code:

// Get the default property from the item definition.
Property defaultValue = definition.GetDefaultProperty(propertyKey);

Debug.Log($"The default value of '{propertyKey}' is {defaultValue.AsString()}");

Compile and start the scene. You should see the following log entry:

! The default value of 'durability' is 20

Getting the current value of the property of an item instance

While the default value of a property cannot be changed in the definition, the item instance can overwrite it.

Append the following code:

// Tries to get the value of the property for the created item
bool found = item.TryGetProperty(propertyKey, out var propertyValue);
if (!found)
{
    Debug.LogError($"item '{definition.displayName}' doesn't have a property '{propertyKey}'");
}
else
{
    Debug.Log($"item '{definition.displayName}' value for '{propertyKey}' is {propertyValue.AsString()}");
}

This new code should log the following message:

! item 'My First Item' value for 'durability' is 20

As expected, the current value is the same as the default one. That's because we haven't played with it yet. That's what we are about to do, with the following code:

item.SetProperty(propertyKey, 18);

propertyValue = item.GetProperty(propertyKey);

Debug.Log($"item '{definition.displayName}' value for '{propertyKey}' is {propertyValue.AsString()}");

Start your scene. Your console should have the following log:

! item 'My First Item' value for 'durability' is 18

As you can see, setting a property is pretty straightforward.

Conclusion

Playing with static properties and [mutable properties] of your catalog items will help you build a better economy for your game.

Going forward

Speaking about economy, now is the time to turn your game into a successful business.

In the next tutorial, we'll talk about transactions. But we'll start smooth with the virtual transactions.

Final source code of this tutorial

using System;
using System.Collections;
using UnityEngine;
using UnityEngine.GameFoundation;
using UnityEngine.GameFoundation.DefaultLayers;
using UnityEngine.Promise;

public class GFInit : MonoBehaviour
{
    IEnumerator Start()
    {
        // Creates a new data layer for Game Foundation,
        // with the default parameters.
        MemoryDataLayer dataLayer = new MemoryDataLayer();

        // Initializes Game Foundation with the data layer.
        Deferred initDeferred = GameFoundationSdk.Initialize(dataLayer);
        yield return initDeferred.Wait();

        if (initDeferred.isFulfilled)
            OnInitSucceeded();
        else
            OnInitFailed(initDeferred.error);

        initDeferred.Release();
    }

    // Called when Game Foundation is successfully initialized.
    void OnInitSucceeded()
    {
        Debug.Log("Game Foundation is successfully initialized");

        // Use the key you've used in the previous tutorial.
        const string definitionKey = "myFirstItem";

        // Finding a definition takes a non-null string parameter.
        InventoryItemDefinition definition = GameFoundationSdk.catalog.Find<InventoryItemDefinition>(definitionKey);

        // Make sure you retrieved a valid definition.
        if (definition is null)
        {
            Debug.Log($"Definition {definitionKey} not found");
            return;
        }

        // You should be able to get information from your definition now.
        Debug.Log($"Definition {definition.key} '{definition.displayName}' found.");

        InventoryItem item = GameFoundationSdk.inventory.CreateItem(definition);

        Debug.Log($"Item {item.id} of definition '{item.definition.key}' created");

        // <---- Insert the following code here

        // This is the key of the property we've created
        const string propertyKey = "durability";

        // Check if the item has the property. Note that you can check
        // the property's existence on both the item and its definition.
        //bool hasProperty = definition.HasProperty(propertyKey);
        bool hasProperty = item.HasProperty(propertyKey);

        if (!hasProperty)
        {
            Debug.LogError($"Cannot find the property {propertyKey}");
            return;
        }

        Debug.Log($"Property '{propertyKey}' found");

        // Get the default property from the item definition.
        Property defaultValue = definition.GetDefaultProperty(propertyKey);

        Debug.Log($"The default value of '{propertyKey}' is {defaultValue.AsString()}");

        // Tries to get the value of the property for the created item
        bool found = item.TryGetProperty(propertyKey, out var propertyValue);
        if (!found)
        {
            Debug.LogError($"item '{definition.displayName}' doesn't have a property '{propertyKey}'");
        }
        else
        {
            Debug.Log($"item '{definition.displayName}' value for '{propertyKey}' is {propertyValue.AsString()}");
        }

        item.SetProperty(propertyKey, 18);

        propertyValue = item.GetProperty(propertyKey);

        Debug.Log($"item '{definition.displayName}' value for '{propertyKey}' is {propertyValue.AsString()}");
    }

    // Called if Game Foundation initialization fails 
    void OnInitFailed(Exception error)
    {
        Debug.LogException(error);
    }
}