Creating a dynamic second scroll list, controlled on the selection of the first dynamic scroll list.

Book Controller Script

using System.Collections; using System.Collections.Generic; using System.IO; using System.Linq; using UnityEngine; using UnityEngine.UI; using UnityEngine.EventSystems; using TMPro; using System;

public class BookController : MonoBehaviour { public string filepath = "DataWriteRead.txt";

 public int LC = 0; // is the number of lines in the text file
 private int longestCategory = 0;
 private string printCategoryTextButton = "";
 private string printItemTextButton = "";
 private int i;
 
 // declarations of Arrays to store Items Data
 private string[] ItemID = new string[1000];
 private string[] ItemNo = new string[1000];
 private string[] ItemName = new string[1000];
 private string[] SelectedItemsName = new string[1000];
 private int differentNames = 0; // is the number of different Categories
 public string[] ItemCategory = new string[1000];
 private int differentCategories = 0; // is the number of different Categories
 private string[] ItemDescription = new string[1000];
 private string[] ItemCalories = new string[1000];
 private string[] ItemGrms = new string[1000];
 private string[] ItemPictureFilePath = new string[1000];
 private string[] uniqueCategory = new string[1000];
 private string[] sortedCategory = new string[1000];
 private string[] sortedNames = new string[1000];
 private int w = 0;
 public string MyTextString = "Martin";
 private ItemController itemController;
 private List<GameObject> buttons;

 [SerializeField] private GameObject buttonTemplate;     //for category buttons
 [SerializeField] private GameObject buttonTemplate2;     //for category buttons


 void Start()
 {
     //Read text file and prepare a table in array format
     ReadFile();

     uniqueCategory = ItemCategory.Distinct().ToArray(); // create an array with unique categories
     
     string[] sortCategory = new string[uniqueCategory.Length - 1]; // create an array that it will be used as the final button list
     string[] sortAlphabeticalOrderC = new string[] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", " ", "@", "%", "$", "€", "-", "+", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" };
     string[] sortedCategory = new string[uniqueCategory.Length];
     int sortedArrayCategoryNo = 0;
     int alphabetLength = sortAlphabeticalOrderC.Length;
     for (int z = 0; z < alphabetLength; z++)
     {
         for (int t = 0; t < sortCategory.Length; t++)
         {
             if (uniqueCategory[t].Substring(0, 1) == sortAlphabeticalOrderC[z])
             {
                 sortedCategory[sortedArrayCategoryNo] = uniqueCategory[t];
                 sortedArrayCategoryNo++;
             }
         }
     }


     // Sort and create the Category Buttons

     for (int t = 0; t < uniqueCategory.Length - 1; t++) //funcion to generate the category Buttons
          {
        
         GameObject button = Instantiate(buttonTemplate) as GameObject; // Create a new button
         button.SetActive(true); // Set the buttons active, false will disable button
         printCategoryTextButton = sortedCategory[t];
         if (printCategoryTextButton is null)
         {
             // do nothing
         }
         else
         {
             button.GetComponent<CategoryButtons>().SetText(printCategoryTextButton); // Set the text of the new button to "Button #" + No
             button.transform.SetParent(buttonTemplate.transform.parent, false); // Set the parent of the new button, as the parent of the button content
             button.GetComponent<CategoryButtons>().myTextString = sortedCategory[t];
         }
        
     } // end of Sort and create the Category Buttons
 }

 

 public void ButtonClicked(string myTextString)
 {
     Debug.Log(myTextString); 
     
     int k = 0;
     for (int g = 0; g < LC; g++) //LC is the number of lines in the text file
     {
         if (ItemCategory[g] == myTextString) //the value of this field is copied from BookController script
         {
             SelectedItemsName[k] = ItemName[g];
             k++;
         }
     }

     int sortedArrayNamesNo = 0;
     int betaLength = 0;
     int beta = 0;
     int h = 0;

     string[] uniqueNames = SelectedItemsName.Distinct().ToArray(); // create an array with unique items Names
     string[] sortNames = new string[uniqueNames.Length - 1]; // create an array that it will be used as the final Name's button list
     string[] SortAlphabeticalOrderN = new string[] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", " ", "@", "%", "$", "€", "-", "+", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" };
     string[] sortedNames = new string[uniqueNames.Length];
     sortedArrayNamesNo = 0;
     betaLength = SortAlphabeticalOrderN.Length;
     for (beta = 0; beta < betaLength; beta++)
     {
         for (h = 0; h < sortNames.Length; h++)
         {
             if (uniqueNames[h].Substring(0, 1) == SortAlphabeticalOrderN[beta])
             {
                 sortNames[sortedArrayNamesNo] = uniqueNames[h];
                 sortedArrayNamesNo++;
             }
         }
     }
     
     //funcion to generate the Item Names Buttons 

     // to clear the buttons already created before creating new once.
     
         buttons = new List<GameObject>();
         Debug.Log(buttons.Count);
         if (buttons.Count > 0)
         {
             foreach (GameObject button in buttons)
             {
                 Destroy(button.gameObject);
             }

             buttons.Clear();
         }

         for (int y = 0; y < uniqueNames.Length - 1; y++)
         {
             GameObject button = Instantiate(buttonTemplate2) as GameObject; // Create a new button
             button.SetActive(true); // Set the buttons active, false will disable button
             printItemTextButton = sortedNames[y];
             if (printItemTextButton is null)
             {
                 // do nothing
             }
             else
             {
                 button.GetComponent<ItemButtons>().SetText2(printItemTextButton); // Set the text of the new button to "Button #" + No
                 button.transform.SetParent(buttonTemplate2.transform.parent, false); // Set the parent of the new button, as the parent of the button content
                 button.GetComponent<ItemButtons>().myTextString2 = sortedNames[y];
             }
         }

     Debug.Log(buttons.Count);

 }

 public void ReadFile()
 {
     // set the file path to create array. Read all file until end   
     using (StreamReader reader = new StreamReader(filepath))
     {
         while (!reader.EndOfStream) // keep reading until you reach the end of file
         {
             string LineData = reader.ReadLine();
             string[] Words = LineData.Split("\t");
             for (i = 0; i < LineData.Length; i++)
                 ItemID[LC] = Words[0];
                 ItemNo[LC] = Words[1];
                 ItemName[LC] = Words[2];
                 ItemCategory[LC] = Words[3];
                 ItemDescription[LC] = Words[4];
                 ItemCalories[LC] = Words[5];
                 ItemGrms[LC] = Words[6];
                 ItemPictureFilePath[LC] = Words[7];
                 LC = LC + 1;
             // i=0, until i < Linedta.length, ie. line in not empty it will get a value more than 0, i++ will proceed, if Line is empty i++ is false and stops
             // LineData is the contect of a whole line
             // the commond Split is used to find the content of each cell
             // "\t" referres to TAB, which is being used as a seperator between fields
             // LC is the number of lines in the text file
             // There are 8 fields in each Line,as given above
         }
     }
 }
 

}

Category Buttons (1st Scroll list)

using System.Collections; using System.Collections.Generic; using System.IO; using System.Linq; using UnityEngine; using UnityEngine.UI; using UnityEngine.EventSystems; using TMPro;

public class CategoryButtons : MonoBehaviour

{ [SerializeField] private TextMeshProUGUI myText; //read Text on Button, the variant type should read TextMeshProUGUI and to include "using TMPro" at start;

 [SerializeField]
 private BookController bookController;

 public string test;
 public string myTextString;
 public Button button;
 
 public void SetText(string textString)  //the textString is the text to be set on the button 
 {
     myTextString = textString;
     myText.text = textString;
     
 }
    
 public void OnClick()
 {
   bookController.ButtonClicked(myTextString);
 }

}

Item Buttons (2nd scroll list buttons

using UnityEngine; using UnityEngine.UI; using TMPro;

public class ItemButtons : MonoBehaviour { [SerializeField] private TextMeshProUGUI myText2; //read Text on Button, the variant type should read TextMeshProUGUI and to include "using TMPro" at start;

 public string myTextString2;
 public void SetText2(string textString2)  //the textString is the text to be set on the button 
 {
     myText2.text = textString2;
 }

   

}