Delphi 5 Developer's Guide (Developer's Guide)

Developer’s Guide 1 Contents 3 Tables 26 Figures 29 Ch 1: Introduction 31 What’s in this manual? 31 Manual conventions 32 Developer support services 33 Part I: Programming with Delphi 35 Ch 2: Developing applications with Delphi 37 Integrated development environment 37 Designing applications 38 Creating projects 39 Editing code 40 Compiling applications 40 Debugging applications 41 Deploying applications 41 Ch 3: Using the component library 43 Understanding the component library 43 Properties, methods, and events 45 Properties 45 Methods 46 Events 46 User events 46 System events 46 Internal events 46 Objects, components, and controls 47 TObject branch 48 TPersistent branch 49 TComponent branch 49 TControl branch 51 TWinControl/TWidgetControl branch 52 Ch 4: Using the object model 53 What is an object? 53 Examining a Delphi object 54 Changing the name of a component 56 Inheriting data and code from an object 57 Scope and qualifiers 57 Private, protected, public, and published declarations 58 Using object variables 59 Creating, instantiating, and destroying objects 60 Components and ownership 61 Defining new classes 61 Using interfaces 64 Using interfaces across the hierarchy 65 Using interfaces with procedures 66 Implementing IInterface 66 TInterfacedObject 67 Using the as operator with interfaces 68 Reusing code and delegation 68 Using implements for delegation 69 Aggregation 70 Memory management of interface objects 70 Using reference counting 71 Not using reference counting 72 Using interfaces in distributed applications 73 Ch 5: Using BaseCLX 75 Using streams 76 Using streams to read or write data 76 Stream methods for reading and writing 76 Reading and writing components 77 Reading and writing strings 77 Copying data from one stream to another 78 Specifying the stream position and size 78 Seeking to a specific position 78 Using Position and Size properties 79 Working with files 79 Approaches to file I/O 80 Using file streams 80 Creating and opening files using filestreams 81 Using the file handle 82 Manipulating files 82 Deleting a file 82 Finding a file 82 Renaming a file 84 File date-time routines 84 Copying a file 85 Working with ini files and the system Registry 85 Using TIniFile and TMemIniFile 86 Using TRegistryIniFile 87 Using TRegistry 87 Working with lists 88 Common list operations 89 Adding list items 89 Deleting list items 89 Accessing list items 90 Rearranging list items 90 Persistent lists 90 Working with string lists 91 Loading and saving string lists 91 Creating a new string list 92 Short-term string lists 92 Long-term string lists 92 Manipulating strings in a list 94 Counting the strings in a list 94 Accessing a particular string 94 Locating items in a string list 94 Iterating through strings in a list 94 Adding a string to a list 95 Moving a string within a list 95 Deleting a string from a list 95 Associating objects with a string list 96 Working with strings 96 Wide character routines 96 Commonly used long string routines 97 Commonly used routines for nullterminatedstrings 100 Declaring and initializing strings 101 Mixing and converting string types 102 String to PChar conversions 102 String dependencies 103 Returning a PChar local variable 103 Passing a local variable as a PChar 103 Compiler directives for strings 104 Creating drawing spaces 105 Printing 106 Converting measurements 107 Performing conversions 107 Performing simple conversions 107 Performing complex conversions 107 Adding new measurement types 108 Creating a simple conversion family andaddingunits 108 Declare variables 109 Register the conversion family 109 Register measurement units 109 Use the new units 109 Using a conversion function 110 Declare variables 110 Register the conversion family 110 Register the base unit 110 Write methods to convert to and fromthebaseunit 110 Register the other units 111 Use the new units 111 Using a class to manage conversions 111 Creating the conversion class 112 Declare variables 113 Register the conversion family and theotherunits 113 Use the new units 114 Defining custom variants 114 Storing a custom variant type’s data 115 Creating a class to enable the customvarianttype 116 Enabling casting 116 Implementing binary operations 118 Implementing comparison operations 120 Implementing unary operations 121 Copying and clearing custom variants 122 Loading and saving custom variant values 123 Using the TCustomVariantType descendant 124 Writing utilities to work with a customvarianttype 124 Supporting properties and methods incustomvariants 125 Using TInvokeableVariantType 125 Using TPublishableVariantType 127 Ch 6: Working with components 129 Setting component properties 130 Setting properties at design time 130 Using property editors 131 Setting properties at runtime 131 Calling methods 131 Working with events and event handlers 131 Generating a new event handler 132 Generating a handler for a component’sdefaultevent 132 Locating event handlers 132 Associating an event with an existing eventhandler 133 Using the Sender parameter 133 Displaying and coding shared events 133 Associating menu events with event handlers 134 Deleting event handlers 134 Cross-platform and non-cross-platform components 135 Adding custom components to the Componentpalette 137 Ch 7: Working with controls 139 Implementing drag and drop in controls 139 Starting a drag operation 139 Accepting dragged items 140 Dropping items 141 Ending a drag operation 141 Customizing drag and drop with a drag object 141 Changing the drag mouse pointer 142 Implementing drag and dock in controls 142 Making a windowed control a docking site 142 Making a control a dockable child 143 Controlling how child controls are docked 143 Controlling how child controls are undocked 144 Controlling how child controls respond todraganddockoperations 144 Working with text in controls 144 Setting text alignment 145 Adding scroll bars at runtime 145 Adding the clipboard object 146 Selecting text 147 Selecting all text 147 Cutting, copying, and pasting text 148 Deleting selected text 148 Disabling menu items 149 Providing a pop-up menu 149 Handling the OnPopup event 150 Adding graphics to controls 151 Indicating that a control is owner-drawn 151 Adding graphical objects to a string list 152 Adding images to an application 152 Adding images to a string list 152 Drawing owner-drawn items 153 Sizing owner-draw items 154 Drawing owner-draw items 155 Ch 8: Building applications, components, and libraries 157 Creating applications 157 GUI applications 158 User interface models 158 SDI applications 158 MDI applications 158 Setting IDE, project, and compiler options 159 Programming templates 159 Console applications 160 Service applications 161 Service threads 164 Service name properties 165 Debugging service applications 166 Creating packages and DLLs 167 When to use packages and DLLs 167 Writing database applications 168 Distributing database applications 169 Creating Web server applications 169 Creating Web Broker applications 170 Creating WebSnap applications 171 Creating Web Services applications 171 Writing applications using COM 172 Using COM and DCOM 172 Using MTS and COM+ 172 Using data modules 173 Creating and editing standard data modules 173 Naming a data module and its unit file 174 Placing and naming components 175 Using component properties and eventsinadatamodule 175 Creating business rules in a data module 176 Accessing a data module from a form 176 Adding a remote data module to an applicationserver project 177 Using the Object Repository 177 Sharing items within a project 177 Adding items to the Object Repository 178 Sharing objects in a team environment 178 Using an Object Repository item in a project 178 Copying an item 178 Inheriting an item 179 Using an item 179 Using project templates 179 Modifying shared items 179 Specifying a default project, new form, andmainform 180 Enabling Help in applications 180 Help system interfaces 181 Implementing ICustomHelpViewer 181 Communicating with the Help Manager 182 Asking the Help Manager for information 182 Displaying keyword-based Help 183 Displaying tables of contents 184 Implementing IExtendedHelpViewer 184 Implementing IHelpSelector 185 Registering Help system objects 186 Registering Help viewers 186 Registering Help selectors 186 Using Help in a VCL application 187 How TApplication processes VCL Help 187 How VCL controls process Help 187 Using Help in a CLX application 188 How TApplication processes CLX Help 188 How CLX controls process Help 188 Calling a Help system directly 189 Using IHelpSystem 189 Customizing the IDE Help system 190 Ch 9: Developing the application user interface 191 Controlling application behavior 191 Working at the application level 192 Handling the screen 192 Setting up forms 193 Using the main form 193 Hiding the main form 193 Adding forms 194 Linking forms 194 Avoiding circular unit references 194 Managing layout 195 Using forms 196 Controlling when forms reside in memory 196 Displaying an auto-created form 196 Creating forms dynamically 197 Creating modeless forms such as windows 198 Creating a form instance using alocalvariable 198 Passing additional arguments to forms 198 Retrieving data from forms 199 Retrieving data from modeless forms 199 Retrieving data from modal forms 201 Reusing components and groups of components 203 Creating and using component templates 203 Working with frames 204 Creating frames 204 Adding frames to the Component palette 205 Using and modifying frames 205 Sharing frames 206 Developing dialog boxes 207 Using open dialog boxes 207 Organizing actions for toolbars and menus 208 What is an action? 209 Setting up action bands 210 Creating toolbars and menus 210 Adding color, patterns, or pictures tomenus,buttons,and toolbars 212 Adding icons to menus and toolbars 212 Selecting menu and toolbar styles 213 Creating dynamic menus 214 Creating toolbars and menus that userscancustomize 214 Hiding unused items and categories inactionbands 214 Creating most recently used (MRU) lists 215 Using action lists 216 Setting up action lists 216 What happens when an action fires 217 Responding with events 217 How actions find their targets 219 Updating actions 219 Predefined action classes 220 Writing action components 221 Registering actions 221 Creating and managing menus 222 Opening the Menu Designer 223 Building menus 224 Naming menus 224 Naming the menu items 224 Adding, inserting, and deleting menu items 225 Adding separator bars 226 Specifying accelerator keys and keyboardshortcuts 226 Creating submenus 227 Creating submenus by demoting existingmenus 227 Moving menu items 228 Adding images to menu items 228 Viewing the menu 229 Editing menu items in the Object Inspector 229 Using the Menu Designer context menu 230 Commands on the context menu 230 Switching between menus at design time 231 Using menu templates 231 Saving a menu as a template 233 Naming conventions for template menu itemsandevent handlers 234 Manipulating menu items at runtime 234 Merging menus 234 Specifying the active menu: Menu property 235 Determining the order of merged menu items: GroupIndex property 235 Importing resource files 235 Designing toolbars and cool bars 236 Adding a toolbar using a panel component 237 Adding a speed button to a panel 237 Assigning a speed button’s glyph 238 Setting the initial condition of a speed button 238 Creating a group of speed buttons 238 Allowing toggle buttons 239 Adding a toolbar using the toolbar component 239 Adding a tool button 239 Assigning images to tool buttons 240 Setting tool button appearance and initialconditions 240 Creating groups of tool buttons 241 Allowing toggled tool buttons 241 Adding a cool bar component 241 Setting the appearance of the cool bar 242 Responding to clicks 242 Assigning a menu to a tool button 242 Adding hidden toolbars 243 Hiding and showing toolbars 243 Demo programs 243 Common controls and XP themes 244 Ch 10: Types of controls 245 Text controls 245 Edit controls 245 Memo and rich edit controls 246 Text viewing controls 247 Labels 247 Specialized input controls 248 Scroll bars 248 Track bars 249 Up-down controls 249 Spin edit controls (CLX only) 249 Hot key controls (VCL only) 250 Splitter controls 250 Buttons and similar controls 250 Button controls 251 Bitmap buttons 251 Speed buttons 252 Check boxes 252 Radio buttons 252 Toolbars 253 Cool bars (VCL only) 253 List controls 253 List boxes and check-list boxes 254 Combo boxes 255 Tree views 255 List views 256 Icon views (CLX only) 256 Date-time pickers and month calendars 256 Grouping controls 256 Group boxes and radio groups 257 Panels 257 Scroll boxes 257 Tab controls 258 Page controls 258 Header controls 258 Display controls 259 Status bars 259 Progress bars 259 Help and hint properties 260 Grids 260 Draw grids 260 String grids 260 Value list editors (VCL only) 261 Graphic controls 262 Images 262 Shapes 262 Bevels 262 Paint boxes 263 Animation control 263 Ch 11: Designing classes and components with ModelMaker 265 ModelMaker fundamentals 266 ModelMaker models 266 Using ModelMaker with the IDE 266 Creating models 267 Using ModelMaker views 268 Collections pane 269 Classes view 269 Units view 269 Diagrams view 270 Members pane 271 Editors pane 271 Implementation Editor 271 Unit Code Editor 272 Diagram Editor 273 Other Editors 273 For more information 274 Ch 12: Working with graphics and multimedia 275 Overview of graphics programming 275 Refreshing the screen 276 Types of graphic objects 277 Common properties and methods of Canvas 278 Using the properties of the Canvas object 279 Using pens 279 Using brushes 282 Reading and setting pixels 283 Using Canvas methods to draw graphic objects 284 Drawing lines and polylines 284 Drawing shapes 285 Handling multiple drawing objects inyourapplication 286 Keeping track of which drawing tool to use 286 Changing the tool with speed buttons 287 Using drawing tools 288 Drawing on a graphic 290 Making scrollable graphics 291 Adding an image control 291 Loading and saving graphics files 293 Loading a picture from a file 293 Saving a picture to a file 294 Replacing the picture 294 Using the clipboard with graphics 295 Copying graphics to the clipboard 296 Cutting graphics to the clipboard 296 Pasting graphics from the clipboard 297 Rubber banding example 298 Responding to the mouse 298 Responding to a mouse-down action 299 Adding a field to a form object to trackmouseactions 301 Refining line drawing 302 Working with multimedia 304 Adding silent video clips to an application 304 Example of adding silent video clips 305 Adding audio and/or video clips to an application 306 Example of adding audio and/or video clips (VCL only) 307 Ch 13: Writing multi-threaded applications 309 Defining thread objects 310 Initializing the thread 311 Assigning a default priority 311 Indicating when threads are freed 312 Writing the thread function 312 Using the main VCL/CLX thread 312 Using thread-local variables 314 Checking for termination by other threads 314 Handling exceptions in the thread function 314 Writing clean-up code 315 Coordinating threads 315 Avoiding simultaneous access 315 Locking objects 316 Using critical sections 316 Using the multi-read exclusive-write synchronizer 316 Other techniques for sharing memory 317 Waiting for other threads 317 Waiting for a thread to finish executing 318 Waiting for a task to be completed 318 Executing thread objects 320 Overriding the default priority 320 Starting and stopping threads 320 Debugging multi-threaded applications 321 Naming a thread 321 Converting an unnamed thread toanamedthread 321 Assigning separate names to similar threads 323 Ch 14: Exception handling 325 Defining protected blocks 326 Writing the try block 326 Raising an exception 327 Writing exception handlers 328 Exception-handling statements 328 Handling classes of exceptions 330 Scope of exception handlers 330 Reraising exceptions 331 Writing finally blocks 332 Writing a finally block 333 Handling exceptions in VCL applications 333 VCL exception classes 334 Default exception handling in VCL 335 Silent exceptions 336 Defining your own VCL exceptions 337 Ch 15: Developing cross-platform applications 339 Creating CLX applications 340 Porting VCL applications 340 Porting techniques 340 Platform-specific ports 341 Cross-platform ports 341 Windows emulation ports 341 Modifying VCL applications 342 WinCLX versus VisualCLX 343 What VisualCLX does differently 344 Features that do not port directly or are missing 345 Comparing WinCLX and VisualCLX units 346 Differences in CLX object constructors 349 Handling system and widget events 350 Writing portable code 350 Using conditional directives 351 Terminating conditional directives 352 Including inline assembler code 353 Programming differences on Linux 354 Transferring applications between WindowsandLinux 355 Sharing source files between WindowsandLinux 355 Environmental differences between WindowsandLinux 356 Registry 358 Look and feel 358 Directory structure on Linux 358 Cross-platform database applications 359 dbExpress differences 360 Component-level differences 360 User interface-level differences 361 Porting database applications to Linux 362 Updating data in dbExpress applications 364 Cross-platform Internet applications 366 Porting Internet applications to Linux 366 Ch 16: Working with packages and components 367 Why use packages? 368 Packages and standard DLLs 368 Runtime packages 369 Loading packages in an application 369 Loading packages with the LoadPackagefunction 370 Deciding which runtime packages to use 370 Custom packages 371 Design-time packages 371 Installing component packages 372 Creating and editing packages 373 Creating a package 373 Editing an existing package 374 Understanding the structure of a package 374 Naming packages 374 Requires clause 375 Contains clause 375 Editing package source files manually 376 Compiling packages 376 Package-specific compiler directives 377 Compiling and linking from the command line 379 Package files created when compiling 379 Deploying packages 380 Deploying applications that use packages 380 Distributing packages to other developers 380 Package collection files 380 Ch 17: Creating international applications 383 Internationalization and localization 383 Internationalization 383 Localization 384 Internationalizing applications 384 Enabling application code 384 ~Character sets 384 OEM and ANSI character sets 385 Multibyte character sets 385 Wide characters 386 Including bi-directional functionality inapplications 386 BiDiMode property 386 Locale-specific features 389 Designing the user interface 389 Text 389 Graphic images 390 Formats and sort order 390 Keyboard mappings 390 Isolating resources 390 Creating resource DLLs 391 Using resource DLLs 392 Dynamic switching of resource DLLs 393 Localizing applications 394 Localizing resources 394 Ch 18: Deploying applications 395 Deploying general applications 395 Using installation programs 396 Identifying application files 396 Application files 397 Package files 397 Merge modules 397 ActiveX controls 399 Helper applications 399 DLL locations 400 Deploying CLX applications 400 Deploying database applications 400 Deploying dbExpress database applications 401 Deploying BDE applications 402 Borland Database Engine 402 Deploying multi-tiered database applications (DataSnap) 403 Deploying Web applications 403 Deploying on Apache servers 404 Enabling modules 404 CGI applications 405 Programming for varying host environments 406 Screen resolutions and color depths 406 Considerations when not dynamically resizing 406 Considerations when dynamically resizingformsandcontrols 407 Accommodating varying color depths 408 Fonts 408 Operating systems versions 409 Software license requirements 409 DEPLOY 409 README 410 No-nonsense license agreement 410 Third-party product documentation 410 Part II: Developing database applications 411 Ch 19: Designing database applications 413 Using databases 413 Types of databases 414 Database security 416 Transactions 416 Referential integrity, stored procedures, andtriggers 417 Database architecture 418 General structure 418 The user interface form 418 The data module 418 Connecting directly to a database server 420 Using a dedicated file on disk 421 Connecting to another dataset 422 Connecting a client dataset to another datasetinthe same application 424 Using a multi-tiered architecture 425 Combining approaches 426 Designing the user interface 427 Analyzing data 427 Writing reports 428 Ch 20: Using data controls 429 Using common data control features 430 Associating a data control with a dataset 431 Changing the associated dataset at runtime 432 Enabling and disabling the data source 432 Responding to changes mediated bythedatasource 432 Editing and updating data 433 Enabling editing in controls on user entry 433 Editing data in a control 433 Disabling and enabling data display 434 Refreshing data display 435 Enabling mouse, keyboard, and timer events 435 Choosing how to organize the data 435 Displaying a single record 435 Displaying data as labels 436 Displaying and editing fields in an edit box 436 Displaying and editing text in a memo control 437 Displaying and editing text in a rich editmemocontrol 437 Displaying and editing graphics fields inanimagecontrol 438 Displaying and editing data in list and combo boxes 438 Handling Boolean field values with checkboxes 441 Restricting field values with radio controls 442 Displaying multiple records 442 Viewing and editing data with TDBGrid 443 Using a grid control in its default state 444 Creating a customized grid 445 Understanding persistent columns 445 Creating persistent columns 446 Deleting persistent columns 447 Arranging the order of persistent columns 447 Setting column properties at design time 448 Defining a lookup list column 449 Putting a button in a column 450 Restoring default values to a column 450 Displaying ADT and array fields 450 Setting grid options 452 Editing in the grid 454 Controlling grid drawing 454 Responding to user actions at runtime 455 Creating a grid that contains other dataaware controls 456 Navigating and manipulating records 457 Choosing navigator buttons to display 458 Hiding and showing navigator buttonsatdesigntime 458 Hiding and showing navigator buttonsatruntime 459 Displaying fly-over help 459 Using a single navigator for multiple datasets 460 Ch 21: Creating reports with Rave Reports 461 Overview 461 Getting started 462 The Rave Visual Designer 463 Component overview 464 VCL/CLX components 464 Engine components 464 Render components 464 Data connection components 464 Rave project component 465 Reporting components 465 Project components 465 Data objects 465 Standard components 465 Drawing components 465 Report components 466 Bar code components 466 Getting more information 466 Ch 22: Using decision support components 467 Overview 467 About crosstabs 468 One-dimensional crosstabs 469 Multidimensional crosstabs 469 Guidelines for using decision support components 470 Using datasets with decision support components 471 Creating decision datasets with TQueryorTTable 472 Creating decision datasets with the DecisionQuery editor 472 Using decision cubes 473 Decision cube properties and events 473 Using the Decision Cube editor 474 Viewing and changing dimension settings 474 Setting the maximum available dimensionsandsummaries 475 Viewing and changing design options 475 Using decision sources 475 Properties and events 475 Using decision pivots 476 Decision pivot properties 476 Creating and using decision grids 477 Creating decision grids 477 Using decision grids 477 Opening and closing decision grid fields 477 Reorganizing rows and columns in decisiongrids 478 Drilling down for detail in decision grids 478 Limiting dimension selection in decisiongrids 478 Decision grid properties 478 Creating and using decision graphs 479 Creating decision graphs 479 Using decision graphs 480 The decision graph display 481 Customizing decision graphs 482 Setting decision graph template defaults 483 Customizing decision graph series 484 Decision support components at runtime 485 Decision pivots at runtime 485 Decision grids at runtime 485 Decision graphs at runtime 486 Decision support components and memorycontrol 486 Setting maximum dimensions, summaries,andcells 486 Setting dimension state 487 Using paged dimensions 487 Ch 23: Connecting to databases 489 Using implicit connections 490 Controlling connections 491 Connecting to a database server 491 Disconnecting from a database server 492 Controlling server login 492 Managing transactions 494 Starting a transaction 495 Ending a transaction 496 Ending a successful transaction 496 Ending an unsuccessful transaction 497 Specifying the transaction isolation level 497 Sending commands to the server 498 Working with associated datasets 500 Closing all datasets without disconnectingfromthe server 500 Iterating through the associated datasets 501 Obtaining metadata 501 Listing available tables 502 Listing the fields in a table 502 Listing available stored procedures 502 Listing available indexes 502 Listing stored procedure parameters 503 Ch 24: Understanding datasets 505 Using TDataSet descendants 506 Determining dataset states 507 Opening and closing datasets 508 Navigating datasets 509 Using the First and Last methods 510 Using the Next and Prior methods 511 Using the MoveBy method 511 Using the Eof and Bof properties 512 Eof 512 Bof 513 Marking and returning to records 513 The Bookmark property 513 The GetBookmark method 514 The GotoBookmark and BookmarkValid methods 514 The CompareBookmarks method 514 The FreeBookmark method 514 A bookmarking example 514 Searching datasets 515 Using Locate 515 Using Lookup 516 Displaying and editing a subset of data usingfilters 517 Enabling and disabling filtering 517 Creating filters 517 Setting the Filter property 518 Writing an OnFilterRecord event handler 519 Switching filter event handlers at runtime 520 Setting filter options 520 Navigating records in a filtered dataset 520 Modifying data 521 Editing records 522 Adding new records 523 Inserting records 523 Appending records 524 Deleting records 524 Posting data 525 Canceling changes 525 Modifying entire records 526 Calculating fields 527 Types of datasets 528 Using table type datasets 529 Advantages of using table type datasets 530 Sorting records with indexes 530 Obtaining information about indexes 531 Specifying an index with IndexName 531 Creating an index with IndexFieldNames 532 Using Indexes to search for records 532 Executing a search with Goto methods 533 Executing a search with Find methods 534 Specifying the current record after a successful search 534 Searching on partial keys 534 Repeating or extending a search 534 Limiting records with ranges 535 Understanding the differences betweenrangesandfilters 535 Specifying ranges 535 Modifying a range 538 Applying or canceling a range 538 Creating master/detail relationships 539 Making the table a detail of another dataset 539 Using nested detail tables 541 Controlling Read/write access to tables 542 Creating and deleting tables 542 Creating tables 542 Deleting tables 545 Emptying tables 545 Synchronizing tables 546 Using query-type datasets 546 Specifying the query 547 Specifying a query using the SQL property 548 Specifying a query using the CommandTextproperty 548 Using parameters in queries 549 Supplying parameters at design time 549 Supplying parameters at runtime 551 Establishing master/detail relationships using parameters 551 Preparing queries 552 Executing queries that don’t return a result set 553 Using unidirectional result sets 553 Using stored procedure-type datasets 554 Working with stored procedure parameters 555 Setting up parameters at design time 556 Using parameters at runtime 558 Preparing stored procedures 559 Executing stored procedures that don’t returnaresult set 559 Fetching multiple result sets 560 Ch 25: Working with field components 561 Dynamic field components 562 Persistent field components 563 Creating persistent fields 564 Arranging persistent fields 565 Defining new persistent fields 565 Defining a data field 566 Defining a calculated field 567 Programming a calculated field 568 Defining a lookup field 569 Defining an aggregate field 570 Deleting persistent field components 571 Setting persistent field properties and events 571 Setting display and edit properties atdesigntime 571 Setting field component properties atruntime 573 Creating attribute sets for field components 573 Associating attribute sets with field components 574 Removing attribute associations 574 Controlling and masking user input 575 Using default formatting for numeric, date,andtimefields 575 Handling events 576 Working with field component methods at runtime 577 Displaying, converting, and accessing field values 578 Displaying field component values in standardcontrols 578 Converting field values 579 Accessing field values with the default datasetproperty 580 Accessing field values with a dataset’s Fieldsproperty 581 Accessing field values with a dataset’s FieldByName method 581 Setting a default value for a field 582 Working with constraints 582 Creating a custom constraint 582 Using server constraints 583 Using object fields 583 Displaying ADT and array fields 584 Working with ADT fields 585 Using persistent field components 585 Using the dataset’s FieldByName method 585 Using the dateset’s FieldValues property 585 Using the ADT field’s FieldValues property 586 Using the ADT field’s Fields property 586 Working with array fields 586 Using persistent fields 586 Using the array field’s FieldValues property 587 Using the array field’s Fields property 587 Working with dataset fields 587 Displaying dataset fields 587 Accessing data in a nested dataset 588 Working with reference fields 588 Displaying reference field