Wednesday, December 7, 2011

Creating a Flex AIR text editor: Part 58

In this tutorial we will add a delete snippet feature.

Find the bDeleteSnippet button in your file and set its click even handler to deleteSnippet() function in SnippetWindow.mxml:

<s:Button id="bDeleteSnippet" label="Delete snippet"  enabled="false" click="deleteSnippet();" />

This function is all that we're going to work with in this tutorial, and it is a pretty complex function.

When deleting a snippet, 3 things need to happen in order. Firstly, the item gets removed from the database. Secondly, all the snippets that were below this snippet have their snippetPosition value updated (each value is substracted by 1, so that we don't have a "hole") in the XML. Thirdly, the same is done but now with SQL database. Moreover, we need to keep in mind that our snippets can be located both in categories and outside of them (root tags).

Firstly we declare 5 variables - currentPos, currentId, currentCategoryID, currentCategoryPos and totalSnippetsBelow. The first four were already introduced and used in previous tutorials in other functions, and the final variable is used store the number of snippets that we need to update. When we declare it, leave it empty.

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;

Now we remove the item from the database using the id provided. Pretty simple:

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

Now we have to check where the snippet is located - a category or root tags. Firstly we will do the code that is executed if the snippet is in a category.

Here we delete the item from the XML, then loop through all the snippets below and update their values (both in XML and SQL):

// 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();
}

}

Root tags now, similar, except for the paths:

// 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();
}

}

Finally, we disable all the selection related components:

// 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;

Full deleteSnippet() function:

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;
}

Full 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;
}
]]>
</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"/>
<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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