Beginning Web Development, Silverlight, and ASP.NET AJAX

More documents

Recommendations

Info

46 CHAPTER 3 ■ WEB FORMS WITH ASP.NET But you can’t, because the text box that you added earlier for txtResult was an ASP.NET HTML control. Based on the fact that web applications are stateless, the server doesn’t recognize the control, and your code will not compile! Why is this the case The answer lies in the fact that ASP.NET was designed for efficiency. For ASP.NET to be able to change the value of a page control when the page posts back, ASP.NET needs to first be made aware that the control could potentially have its value changed, and then ASP.NET needs to keep track of the value. This is called control state. We’ll see how to do this in the next section. For completeness, I should mention that if you don’t want to use the input text control to return the mathematical result to the user, you could use the Page.Response (HttpResponse) stream to write HTML directly to the response stream, overwriting the default HTML to be returned to the client (i.e., the HTML that makes up your form) with your own content. However, this isn’t recommended in general, because you will completely overwrite your application within the browser. Using a Server Control to Provide Feedback Earlier, you added an ASP.NET HTML text box to your page markup with the expectation that it could be used to store the results of the mathematical operation. But simply assigning the mathematical result to the text box will yield a compilation error. Clearly ASP.NET needs to provide a mechanism for returning calculated page values to the user! The answer to providing feedback to a form operation is to introduce the control to ASP.NET’s view state mechanism, which can be done in one of two ways. If you want to continue to use the HTML input text box, simply add this attribute to its definition in your page markup: runat="server" Since the control has a name attribute but not an id attribute, which ASP.NET requires, you also need to add this: id="txtResult" By doing this, you make ASP.NET aware that this control, txtResult, should be accessible on the server (allowing you to change its content, or state). But you may elect to forego the ASP.NET HTML controls and instead use the fullfledged ASP.NET server controls. In the following example, you’ll modify the previous example to use a server-side Literal control, and this control will be populated with the results of the operation. Go back to Design view for the Default.aspx page and amend it by removing the txtResults HTML control and replacing it with an ASP.NET Literal control. You can find this control on the Standard Visual Studio Toolbox tab. Once you’ve done so, your screen should look like Figure 3-3.
CHAPTER 3 ■ WEB FORMS WITH ASP.NET 47 Figure 3-3. Using the ASP.NET Literal control in your page The listing for this page will look like Listing 3-5. Listing 3-5. The Revised Form Untitled Page First Number Second Number Add
Page 1:
The EXPERT’s VOIce ® in .NET Beg
Page 4 and 5:
Beginning Web Development, Silverli
Page 6 and 7:
2ca983ba3745582e6151dc1b079b2db0
Page 9 and 10:
Contents About the Author . . . . .
Page 11 and 12:
■CONTENTS ix ■CHAPTER 5 ASP.NET
Page 13 and 14:
■CONTENTS xi ■CHAPTER 11 Ajax A
Page 15 and 16:
■CONTENTS xiii ■CHAPTER 15 Enha
Page 17: About the Author ■LAURENCE MORONE
Page 21 and 22: Introduction This book is aimed at
Page 23: PART 1 Building Web Applications
Page 26 and 27: 4 CHAPTER 1 ■ INTRODUCTION TO WEB
Page 32 and 33: 10 CHAPTER 2 ■ BASICS OF WEB DEVE
Page 60 and 61: 38 CHAPTER 3 ■ WEB FORMS WITH ASP
Page 91 and 92: CHAPTER 4 Data Binding with ASP.NET
Page 93 and 94: CHAPTER 4 ■ DATA BINDING WITH ASP
Page 119 and 120:
CHAPTER 4 ■ DATA BINDING WITH ASP
Page 121 and 122:
Page 123 and 124:
Page 125:
Page 128 and 129:
106 CHAPTER 5 ■ ASP.NET WEB SERVI
Page 130 and 131:
Page 132 and 133:
Page 134 and 135:
Page 136 and 137:
Page 138 and 139:
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
Page 146 and 147:
Page 148 and 149:
Page 151 and 152:
CHAPTER 6 Deploying Your Web Site I
Page 153 and 154:
CHAPTER 6 ■ DEPLOYING YOUR WEB SI
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173:
Page 177 and 178:
CHAPTER 7 .NET 3.0: Windows Communi
Page 179 and 180:
CHAPTER 7 ■ .NET 3.0: WINDOWS COM
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
CHAPTER 8 .NET 3.0: Windows Present
Page 201 and 202:
CHAPTER 8 ■ .NET 3.0: WINDOWS PRE
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
CHAPTER 9 .NET 3.0: Windows Workflo
Page 233 and 234:
CHAPTER 9 ■ .NET 3.0: WINDOWS WOR
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
Page 247 and 248:
Page 249 and 250:
Page 251 and 252:
Page 253:
Page 256 and 257:
234 CHAPTER 10 ■ .NET 3.0: PROGRA
Page 258 and 259:
Page 260 and 261:
Page 262 and 263:
Page 264 and 265:
Page 266 and 267:
Page 268 and 269:
Page 270 and 271:
Page 272 and 273:
Page 275 and 276:
CHAPTER 11 Ajax Applications and Em
Page 277 and 278:
CHAPTER 11 ■ AJAX APPLICATIONS AN
Page 279 and 280:
Page 281 and 282:
Page 283 and 284:
Page 285 and 286:
Page 287 and 288:
Page 289 and 290:
Page 291 and 292:
Page 293 and 294:
Page 295 and 296:
Page 297 and 298:
Page 299 and 300:
Page 301 and 302:
CHAPTER 12 AJAX Extensions for ASP.
Page 303 and 304:
CHAPTER 12 ■ AJAX EXTENSIONS FOR
Page 305 and 306:
Page 307 and 308:
Page 309 and 310:
Page 311 and 312:
Page 313 and 314:
Page 315 and 316:
Page 317 and 318:
Page 319 and 320:
Page 321 and 322:
Page 323 and 324:
Page 325 and 326:
Page 327 and 328:
Page 329 and 330:
Page 331 and 332:
CHAPTER 13 Ajax Scripts and Service
Page 333 and 334:
CHAPTER 13 ■ AJAX SCRIPTS AND SER
Page 335 and 336:
Page 337 and 338:
Page 339 and 340:
Page 341 and 342:
Page 343 and 344:
Page 345 and 346:
Page 347 and 348:
Page 349 and 350:
Page 351:
Page 354 and 355:
332 CHAPTER 14 ■ JAVASCRIPT PROGR
Page 356 and 357:
Page 358 and 359:
Page 360 and 361:
Page 362 and 363:
Page 364 and 365:
Page 366 and 367:
Page 368 and 369:
Page 370 and 371:
Page 372 and 373:
Page 375 and 376:
CHAPTER 15 Enhancing the Web Experi
Page 377 and 378:
CHAPTER 15 ■ ENHANCING THE WEB EX
Page 379 and 380:
Page 381 and 382:
Page 383 and 384:
Page 385 and 386:
Page 387 and 388:
Page 389 and 390:
Page 391 and 392:
Page 393 and 394:
Page 395:
Page 398 and 399:
376 CHAPTER 16 ■ PROGRAMMING SILV
Page 400 and 401:
Page 402 and 403:
Page 404 and 405:
Page 406 and 407:
Page 408 and 409:
Page 410 and 411:
Page 412 and 413:
Page 414 and 415:
Page 416 and 417:
Page 418 and 419:
Page 420 and 421:
Page 422 and 423:
Page 424 and 425:
Page 426 and 427:
Page 428 and 429:
Page 430 and 431:
Page 432 and 433:
Page 434 and 435:
Page 436 and 437:
Page 438 and 439:
416 ■INDEX applications. See also
Page 440 and 441:
418 ■INDEX copying web sites, 25
Page 442 and 443:
420 ■INDEX ■H H path language c
Page 444 and 445:
422 ■INDEX object orientation, 16
Page 446 and 447:
424 ■INDEX Sequential Workflow Co
Page 448 and 449:
426 ■INDEX ■V V path language c
show all

Beginning Web Development, Silverlight, and ASP.NET AJAX

Create successful ePaper yourself

Delete template?

Save as template?