Thursday, December 8, 2011

Creating a Flex AIR text editor: Part 59

In this tutorial we will add the ability to remove snippet categories.

When a category is deleted, all its contents also are to be deleted. Moreover, all the categories below the one that's deleted need to have their categoryPosition value updated.

First of all add a click listener for the bDeleteCategory button. Set the event handler to a function called deleteCategory().

<s:Button id="bDeleteCategory" label="Delete category with its contents" enabled="false" click="deleteCategory();" />

Now we fill this function with content. The first thing we're going to do is declare 3 variables - currentID, currentPos and totalCategoriesBelow. On declaration, set the first two variables to the id and categoryPosition values of the tree's selected item.

private function deleteCategory():void {
var currentID:int = snippetManageTree.selectedItem.@id;
var currentPos:int = snippetManageTree.selectedItem.@categoryPosition;
var totalCategoriesBelow:int;

}

Now we need to delete the category from the database. This is easy, since we all we need to do is call one statement and specify the id of the item:

// Delete category from database

var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = categoryConnection;
stat.text = "DELETE FROM categories WHERE id=" + currentID;
stat.execute();

Now we delete all the snippets belonging to this category, also from the database.

// Delete all snippets belonging to this category

var stat2:SQLStatement = new SQLStatement();
stat2.sqlConnection = snippetConnection;
stat2.text = "DELETE FROM snippets WHERE categoryID=" + currentID;
stat2.execute();

Next, we can remove the category from the xml.

// Delete from the xml

delete treeData.category[currentPos];

Now we need to loop through the categories that are below this one and update their categoryPosition. This is done using a loop similar to the one from the previous tutorial:

// Increase categoryPosition of all categories below
totalCategoriesBelow = treeData.category.length() - currentPos;

for (var i:int = 0; i < totalCategoriesBelow; i++) {
treeData.category[currentPos + i].@categoryPosition = currentPos + i;

var stat3:SQLStatement = new SQLStatement();
stat3.sqlConnection = categoryConnection;
stat3.text = "UPDATE categories SET categoryPosition=@categoryPosition WHERE categoryPosition=" + (currentPos + i);
stat3.parameters["@categoryPosition"] = currentPos + i - 1;
stat3.execute();
}

Finally we disable all selection enabled things:

// Disable all selection enabled components

bSaveSnippet.enabled = false;
bDeleteSnippet.enabled = false;
bSaveCategory.enabled = false;
bDeleteCategory.enabled = false;
upCategory.enabled = false;
downCategory.enabled = false;
upSnippet.enabled = false;
downSnippet.enabled = false;

The full function code:

private function deleteCategory():void {
var currentID:int = snippetManageTree.selectedItem.@id;
var currentPos:int = snippetManageTree.selectedItem.@categoryPosition;
var totalCategoriesBelow:int;

// Delete category from database

var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = categoryConnection;
stat.text = "DELETE FROM categories WHERE id=" + currentID;
stat.execute();

// Delete all snippets belonging to this category

var stat2:SQLStatement = new SQLStatement();
stat2.sqlConnection = snippetConnection;
stat2.text = "DELETE FROM snippets WHERE categoryID=" + currentID;
stat2.execute();

// Delete from the xml

delete treeData.category[currentPos];

// Increase categoryPosition of all categories below
totalCategoriesBelow = treeData.category.length() - currentPos;

for (var i:int = 0; i < totalCategoriesBelow; i++) {
treeData.category[currentPos + i].@categoryPosition = currentPos + i;

var stat3:SQLStatement = new SQLStatement();
stat3.sqlConnection = categoryConnection;
stat3.text = "UPDATE categories SET categoryPosition=@categoryPosition WHERE categoryPosition=" + (currentPos + i);
stat3.parameters["@categoryPosition"] = currentPos + i - 1;
stat3.execute();
}

// Disable all selection enabled components

bSaveSnippet.enabled = false;
bDeleteSnippet.enabled = false;
bSaveCategory.enabled = false;
bDeleteCategory.enabled = false;
upCategory.enabled = false;
downCategory.enabled = false;
upSnippet.enabled = false;
downSnippet.enabled = false;
}

And now SnippetWindow.mxml code:

<?xml version="1.0" encoding="utf-8"?>
<mx:Window xmlns:fx="http://ns.adobe.com/mxml/2009" 
xmlns:s="library://ns.adobe.com/flex/spark" 
xmlns:mx="library://ns.adobe.com/flex/mx"
xmlns:custom="*"
title="Snippet management" type="utility" width="500" height="730"
creationComplete="init();" showStatusBar="false" alwaysInFront="true" resizable="false" backgroundColor="#dddddd">

<fx:Script>
<![CDATA[
import flash.data.SQLConnection;
import flash.data.SQLResult;
import flash.data.SQLStatement;
import flash.events.Event;
import flash.net.Responder;
import mx.controls.Alert;

[Bindable]
public var treeData:XMLList;
private var snippetConnection:SQLConnection;
private var categoryConnection:SQLConnection;
[Bindable]
private var categories:Array = [];

private function init():void{
this.addEventListener(Event.CLOSING, onClose);
}

private function onClose(evt:Event):void {
this.visible = false;
evt.preventDefault();
}

public function setValues(xmlData:XMLList, conn1:SQLConnection, conn2:SQLConnection, createNewOnStart:Boolean = false, newText:String = ""):void {
snippetConnection = conn1;
categoryConnection = conn2;
treeData = xmlData;
newTextInput.text = newText;
newNameInput.text = "New snippet name here";
if (newText=="") {
newTextInput.text = "New snippet text here";
}
updateCategoryCombo();
}

private function addSnippet(name:String, text:String):void{
if (name != "" && text != "") {
var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = snippetConnection;
stat.text = "INSERT INTO snippets (snippetName, snippetText, categoryID, snippetPosition) VALUES (@snippetName, @snippetText, @categoryID, @snippetPosition);"
stat.parameters["@snippetName"] = name;
stat.parameters["@snippetText"] = text;
stat.parameters["@categoryID"] = categoryCombo.selectedItem.ind;
stat.parameters["@snippetPosition"] = totalItemsIn(categoryCombo.selectedItem.ind);
stat.execute(-1, new Responder(addSnippetXML));
}else {
Alert.show("The name and text of the snippet must not be blank!","Oops!");
}
}

private function addSnippetXML(evt:SQLResult):void {
if (treeData.category.length() == 0 && treeData..snippet.length() == 0) {
treeData = new XMLList(<root></root>);
}
var aSnippet:XML = <snippet/>;
aSnippet.@id = evt.lastInsertRowID;
aSnippet.@label = newNameInput.text;
aSnippet.@categoryID = categoryCombo.selectedItem.ind;
aSnippet.@snippetPosition = totalItemsIn(categoryCombo.selectedItem.ind);
aSnippet.@isBranch = false;
if(aSnippet.@categoryID!=-1){
treeData.category.(@id == categoryCombo.selectedItem.ind).appendChild(aSnippet);
}else {
treeData[0].appendChild(aSnippet);
}
}

private function addCategory(name:String):void {
if (name != "") {
var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = categoryConnection;
stat.text = "INSERT INTO categories (categoryName, categoryPosition) VALUES (@categoryName, @categoryPosition);"
stat.parameters["@categoryName"] = name;
stat.parameters["@categoryPosition"] = treeData.category.length();
stat.execute(-1, new Responder(addCategoryXML));
}else {
Alert.show("The name of the category must not be blank!","Oops!");
}
}

private function addCategoryXML(evt:SQLResult):void {
if (treeData.category.length() == 0 && treeData..snippet.length() == 0) {
treeData = new XMLList(<root></root>);
}
var aCategory:XML = <category/>;
aCategory.@id = evt.lastInsertRowID;
aCategory.@label = newCategoryInput.text;
aCategory.@categoryPosition = treeData.category.length();
aCategory.@isBranch = true;
if(treeData.category.length()>0){
var prevLastCategory:XML = treeData.category[treeData.category.length()-1];
treeData[0].insertChildAfter(prevLastCategory, aCategory);
} else
if(treeData[0].snippet.length()>0){
var firstSnippet:XML = treeData[0].snippet[0];
treeData[0].insertChildBefore(firstSnippet, aCategory);
} else {
treeData[0].appendChild(aCategory);
}
snippetManageTree.selectedItem = aCategory;
selectTree();
updateCategoryCombo();
}

private function updateCategoryCombo():void{
categories = [];
categories.push( { label:"No category", ind: -1 } );
for each (var cat:XML in treeData.category) {
categories.push({label:cat.@label, ind:cat.@id});
}
categoryCombo.selectedIndex = 0;
}

private function totalItemsIn(id:int):int {
var toRet:int;
if(id>=0){
toRet = treeData.category.(@id == id).children().length();
}
if (id == -1) {
toRet = treeData.snippet.length();
}
return toRet;
}

private function selectTree():void {
bSaveSnippet.enabled = false;
bDeleteSnippet.enabled = false;
bSaveCategory.enabled = false;
bDeleteCategory.enabled = false;
upCategory.enabled = false;
downCategory.enabled = false;
upSnippet.enabled = false;
downSnippet.enabled = false;

if (snippetManageTree.selectedItem.@isBranch == true) {
bSaveCategory.enabled = true;
bDeleteCategory.enabled = true;
upCategory.enabled = canCategoryUp();
downCategory.enabled = canCategoryDown();
newCategoryInput.text = snippetManageTree.selectedItem.@label;
} else {
bSaveSnippet.enabled = true;
bDeleteSnippet.enabled = true;
upSnippet.enabled = canSnippetUp();
downSnippet.enabled = canSnippetDown();
categoryCombo.selectedIndex = treeData.category.(@id == snippetManageTree.selectedItem.@categoryID).@categoryPosition + 1;
if (snippetManageTree.selectedItem.@categoryID == -1) {
categoryCombo.selectedIndex = 0;
}
var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = snippetConnection;
stat.text = "SELECT snippetText FROM snippets WHERE id=" + snippetManageTree.selectedItem.@id;
stat.execute( -1, new Responder(loadSnippetText));
}
}

private function loadSnippetText(evt:SQLResult):void{
newNameInput.text = snippetManageTree.selectedItem.@label;
newTextInput.text = evt.data[0].snippetText;
}

private function canCategoryUp():Boolean {
var toRet:Boolean = true;
if (snippetManageTree.selectedItem.@categoryPosition == 0) {
toRet = false;
}
return toRet;
}

private function canCategoryDown():Boolean {
var toRet:Boolean = true;
if (snippetManageTree.selectedItem.@categoryPosition == (treeData.category.length()-1)) {
toRet = false;
}
return toRet;
}

private function canSnippetUp():Boolean {
var toRet:Boolean = true;
if (snippetManageTree.selectedItem.@snippetPosition == 0) {
toRet = false;
}
return toRet;
}

private function canSnippetDown():Boolean {
var toRet:Boolean = true;
if (snippetManageTree.selectedItem.@categoryID != -1 && snippetManageTree.selectedItem.@snippetPosition == (treeData.category.(@id == snippetManageTree.selectedItem.@categoryID).children().length()-1)) {
toRet = false;
}
if (snippetManageTree.selectedItem.@snippetPosition == (treeData.snippet.length()-1)) {
toRet = false;
}
return toRet;
}

private function categoryMove(dir:String):void{
var currentPos:int = snippetManageTree.selectedItem.@categoryPosition;
var currentId:int = snippetManageTree.selectedItem.@id;
var newPos:int = (dir=="up")?(currentPos - 1):(currentPos + 1);

// Databases:

// Set the above category's position to current one
var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = categoryConnection;
stat.text = "UPDATE categories SET categoryPosition=@currentPos WHERE categoryPosition=@newPos"
stat.parameters["@newPos"] = newPos;
stat.parameters["@currentPos"] = currentPos;
stat.execute();

// Set the current category's position to the one above
var stat2:SQLStatement = new SQLStatement();
stat2.sqlConnection = categoryConnection;
stat2.text = "UPDATE categories SET categoryPosition=@newPos WHERE id=@currentId"
stat2.parameters["@newPos"] = newPos;
stat2.parameters["@currentId"] = currentId;
stat2.execute();

// XML:

var copy:XML = treeData.category[currentPos].copy();
delete treeData.category[currentPos];
if(dir=="up"){
treeData.insertChildBefore(treeData.category[newPos], copy);
}else {
treeData.insertChildAfter(treeData.category[currentPos], copy);
}
copy.@categoryPosition = newPos;
treeData.category[currentPos].@categoryPosition = currentPos;
snippetManageTree.selectedItem = copy;
selectTree();
}

private function snippetMove(dir:String):void{
var currentPos:int = snippetManageTree.selectedItem.@snippetPosition;
var currentId:int = snippetManageTree.selectedItem.@id;
var newPos:int = (dir == "up")?(currentPos - 1):(currentPos + 1);
var currentCategoryID:int = snippetManageTree.selectedItem.@categoryID;
var currentCategoryPos:int = NaN;

if (currentCategoryID != -1) {
currentCategoryPos = treeData.category.(@id == currentCategoryID).@categoryPosition;
}

// Databases:

// Set the above category's position to current one
var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = snippetConnection;
stat.text = "UPDATE snippets SET snippetPosition=@currentPos WHERE snippetPosition=@newPos"
stat.parameters["@newPos"] = newPos;
stat.parameters["@currentPos"] = currentPos;
stat.execute();

// Set the current category's position to the one above
var stat2:SQLStatement = new SQLStatement();
stat2.sqlConnection = snippetConnection;
stat2.text = "UPDATE snippets SET snippetPosition=@newPos WHERE id=@currentId"
stat2.parameters["@newPos"] = newPos;
stat2.parameters["@currentId"] = currentId;
stat2.execute();

// XML:

var copy:XML = new XML();

if(currentCategoryID != -1){
copy = treeData.category[currentCategoryPos].snippet[currentPos].copy();
delete treeData.category[currentCategoryPos].snippet[currentPos];
if(dir=="up"){
treeData.category[currentCategoryPos].insertChildBefore(treeData.category[currentCategoryPos].snippet[newPos], copy);
}else {
treeData.category[currentCategoryPos].insertChildAfter(treeData.category[currentCategoryPos].snippet[currentPos], copy);
}
copy.@snippetPosition = newPos;
treeData.category[currentCategoryPos].snippet[currentPos].@snippetPosition = currentPos;
}

if(currentCategoryID == -1){
copy = treeData.snippet[currentPos].copy();
delete treeData.snippet[currentPos];
if(dir=="up"){
treeData.insertChildBefore(treeData.snippet[newPos], copy);
}else {
treeData.insertChildAfter(treeData.snippet[currentPos], copy);
}
copy.@snippetPosition = newPos;
treeData.snippet[currentPos].@snippetPosition = currentPos;
}

snippetManageTree.selectedItem = copy;
selectTree();
}

private function saveCategory():void {
var currentID:int = snippetManageTree.selectedItem.@id;

var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = categoryConnection;
stat.text = "UPDATE categories SET categoryName=@categoryName WHERE id=" + currentID;
stat.parameters["@categoryName"] = newCategoryInput.text;
stat.execute();

treeData.category[snippetManageTree.selectedItem.@categoryPosition].@label = newCategoryInput.text;
updateCategoryCombo();
}

private function saveSnippet():void {
var currentID:int = snippetManageTree.selectedItem.@id;

var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = snippetConnection;
stat.text = "UPDATE snippets SET snippetName=@snippetName, snippetText=@snippetText WHERE id=" + currentID;
stat.parameters["@snippetName"] = newNameInput.text;
stat.parameters["@snippetText"] = newTextInput.text;
stat.execute();

var currentPos:int = snippetManageTree.selectedItem.@snippetPosition;
var currentCategoryID:int = snippetManageTree.selectedItem.@categoryID;
var currentCategoryPos:int;

if (currentCategoryID != -1) {
currentCategoryPos = treeData.category.(@id == currentCategoryID).@categoryPosition;
treeData.category[currentCategoryPos].snippet[currentPos].@label = newNameInput.text;
}else {
treeData.snippet[currentPos].@label = newNameInput.text;
}

}

private function deleteSnippet():void {
var currentPos:int = snippetManageTree.selectedItem.@snippetPosition;
var currentId:int = snippetManageTree.selectedItem.@id;
var currentCategoryID:int = snippetManageTree.selectedItem.@categoryID;
var currentCategoryPos:int = NaN;

if (currentCategoryID != -1) {
currentCategoryPos = treeData.category.(@id == currentCategoryID).@categoryPosition;
}
var totalSnippetsBelow:int;

// Delete from the SQL database
var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = snippetConnection;
stat.text = "DELETE FROM snippets WHERE id=" + currentId;
stat.execute();

// If in a category:
if (currentCategoryID != -1) {

// Delete from the XML
delete treeData.category[currentCategoryPos].snippet[currentPos];

// Increase snippetPosition of all snippets below
totalSnippetsBelow = treeData.category[currentCategoryPos].children().length() - currentPos;

for (var i:int = 0; i < totalSnippetsBelow; i++) {
treeData.category[currentCategoryPos].snippet[currentPos + i].@snippetPosition = currentPos + i;

var snipStat1:SQLStatement = new SQLStatement();
snipStat1.sqlConnection = snippetConnection;
snipStat1.text = "UPDATE snippets SET snippetPosition=@snippetPosition WHERE snippetPosition=" + (currentPos + i);
snipStat1.parameters["@snippetPosition"] = currentPos + i - 1;
snipStat1.execute();
}

}

// If in a root tags:
if (currentCategoryID == -1) {

// Delete from the XML
delete treeData.snippet[currentPos];

// Increase snippetPosition of all snippets below
totalSnippetsBelow = treeData.snippet.length() - currentPos;

for (var u:int = 0; u < totalSnippetsBelow; u++) {
treeData.snippet[currentPos + u].@snippetPosition = currentPos + u;

var snipStat2:SQLStatement = new SQLStatement();
snipStat2.sqlConnection = snippetConnection;
snipStat2.text = "UPDATE snippets SET snippetPosition=@snippetPosition WHERE snippetPosition=" + (currentPos + u);
snipStat2.parameters["@snippetPosition"] = currentPos + u - 1;
snipStat2.execute();
}

}

// Disable all selection enabled components

bSaveSnippet.enabled = false;
bDeleteSnippet.enabled = false;
bSaveCategory.enabled = false;
bDeleteCategory.enabled = false;
upCategory.enabled = false;
downCategory.enabled = false;
upSnippet.enabled = false;
downSnippet.enabled = false;
}

private function deleteCategory():void {
var currentID:int = snippetManageTree.selectedItem.@id;
var currentPos:int = snippetManageTree.selectedItem.@categoryPosition;
var totalCategoriesBelow:int;

// Delete category from database

var stat:SQLStatement = new SQLStatement();
stat.sqlConnection = categoryConnection;
stat.text = "DELETE FROM categories WHERE id=" + currentID;
stat.execute();

// Delete all snippets belonging to this category

var stat2:SQLStatement = new SQLStatement();
stat2.sqlConnection = snippetConnection;
stat2.text = "DELETE FROM snippets WHERE categoryID=" + currentID;
stat2.execute();

// Delete from the xml

delete treeData.category[currentPos];

// Increase categoryPosition of all categories below
totalCategoriesBelow = treeData.category.length() - currentPos;

for (var i:int = 0; i < totalCategoriesBelow; i++) {
treeData.category[currentPos + i].@categoryPosition = currentPos + i;

var stat3:SQLStatement = new SQLStatement();
stat3.sqlConnection = categoryConnection;
stat3.text = "UPDATE categories SET categoryPosition=@categoryPosition WHERE categoryPosition=" + (currentPos + i);
stat3.parameters["@categoryPosition"] = currentPos + i - 1;
stat3.execute();
}

// Disable all selection enabled components

bSaveSnippet.enabled = false;
bDeleteSnippet.enabled = false;
bSaveCategory.enabled = false;
bDeleteCategory.enabled = false;
upCategory.enabled = false;
downCategory.enabled = false;
upSnippet.enabled = false;
downSnippet.enabled = false;
}
]]>
</fx:Script>

<s:VGroup paddingLeft="5" paddingRight="5" paddingTop="5" paddingBottom="5">
<s:Label text="Snippet creation and management: " />
<s:HGroup>
<s:TextInput id="newNameInput" text="New snippet name" width="240" />
<mx:ComboBox id="categoryCombo" width="240" dataProvider="{categories}" />
</s:HGroup>
<s:TextArea id="newTextInput" width="490" height="200" text="Snippet text" />
<s:HGroup>
<s:Button id="bAddSnippet" label="Add snippet" click="addSnippet(newNameInput.text, newTextInput.text);" />
<s:Button id="bSaveSnippet" label="Save changes" enabled="false" />
<s:Button id="bDeleteSnippet" label="Delete snippet"  enabled="false" click="deleteSnippet();" />
<custom:IconButton id="upSnippet" icon="@Embed('../lib/arrow_up.png')" toolTip="Move up" enabled="false" click="snippetMove('up');" />
<custom:IconButton id="downSnippet" icon="@Embed('../lib/arrow_down.png')" toolTip="Move down" enabled="false" click="snippetMove('down');" />
</s:HGroup>

<s:Label text="" />

<s:Label text="Category creation and management: " />
<s:TextInput id="newCategoryInput" text="New category name" width="490" />
<s:HGroup>
<s:Button id="bAddCategory" label="Add category" click="addCategory(newCategoryInput.text);"/>
<s:Button id="bSaveCategory" label="Save changes" enabled="false" click="saveCategory();" />
<s:Button id="bDeleteCategory" label="Delete category with its contents" enabled="false" click="deleteCategory();" />
<custom:IconButton id="upCategory" icon="@Embed('../lib/arrow_up.png')" toolTip="Move up" enabled="false" click="categoryMove('up');" />
<custom:IconButton id="downCategory" icon="@Embed('../lib/arrow_down.png')" toolTip="Move down" enabled="false" click="categoryMove('down');" />
</s:HGroup>

<s:Label text="" />

<mx:Tree id="snippetManageTree" dataProvider="{treeData}" width="490" height="300" showRoot="false" labelField="@label" itemClick="selectTree();" />
</s:VGroup>

</mx:Window>

Thanks for reading!

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