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Wiki source code of Your First Rest Project

Version 22.1 by Filippo Laurìa on 2013/07/22 12:39
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1
2
3 {{toc/}}
4
5 = Introduction =
6
7 In the first part of the Blog tutorial, you will learn:
8
9 * How to create a EOModel for the database (we will use H2)
10 * How to use migrations to create the database tables
11 * How to use ERRest to create blog posts with JSON format and how to display the blog posts in HTML for readers
12
13 = Create a new project =
14
15 You will need to create a new project for this tutorial. In Eclipse, open the **File** menu, select **New** and select **Wonder REST Application**. Name your project as //BlogRest//.
16
17 = Create the database model =
18
19 == Database structure ==
20
21 We will build a small database model for the blog. The database will have two tables: BlogEntry and Author.
22
23 BlogEntry will have the following columns:
24
25 |=(((
26 Column name
27 )))|=(((
28 Type
29 )))|=(((
30 Constraints
31 )))
32 |(((
33 id
34 )))|(((
35 integer
36 )))|(((
37 primary key
38 )))
39 |(((
40 title
41 )))|(((
42 string(255)
43 )))|(((
44
45 )))
46 |(((
47 content
48 )))|(((
49 string(4000)
50 )))|(((
51
52 )))
53 |(((
54 creationDate
55 )))|(((
56 timestamp
57 )))|(((
58
59 )))
60 |(((
61 lastModified
62 )))|(((
63 timestamp
64 )))|(((
65
66 )))
67 |(((
68 author
69 )))|(((
70 integer
71 )))|(((
72 relation with Author
73 )))
74
75 Author will have the following columns:
76
77 |=(((
78 Column name
79 )))|=(((
80 Type
81 )))|=(((
82 Constraints
83 )))
84 |(((
85 id
86 )))|(((
87 integer
88 )))|(((
89 primary key
90 )))
91 |(((
92 firstName
93 )))|(((
94 string(50)
95 )))|(((
96
97 )))
98 |(((
99 lastName
100 )))|(((
101 string(50)
102 )))|(((
103
104 )))
105 |(((
106 email
107 )))|(((
108 string(100)
109 )))|(((
110 unique
111 )))
112
113 == Creating the EOModel ==
114
115 To create the database, we will first create a EOModel and use migrations to build the database on the file system (H2 will take care of creating the database file).
116
117 An EOModel consists of entities, attributes and relationships. When using it in a RDBMS context, an entity is a table (or a view), an attribute is a table column and a relationship is a join between two tables.
118
119 To create the EOModel, in the project right-click on the project name and select **New** -> **EOModel**.
120
121 Name it **BlogModel** and in the plugin list, select **H2**. Click **Finish**.
122
123 The model should show up in a window that looks like this:
124
125 [[image:attach:EOModeler.png]]
126
127 If it didn't show up, the window might have opened behind the main Eclipse window. If that's the case, open the **Window** menu and select the windows that have //Entity Modeler// in its name.
128
129 In the Entity Modeler window, click on **Default**, and for the **URL** field, type
130
131 {{code}}
132 jdbc:h2:~/BlogTutorial
133 {{/code}}
134
135 . When the database will be created, it will be stored in your home directory (/Users/youruser/ on OS X).
136
137 Now, right-click on **BlogModel** and select **New Entity**.
138
139 Type the following details in the **Basic** tab:
140
141 * **Name**: BlogEntry
142 * **Table Name**: BlogEntry
143 * **Class Name**: your.app.model.BlogEntry
144
145 Now, it's time to add the entity's attributes (aka, the table's columns). You will see that the entity already have an attributed named "id". That attribute is a integer for the primary key. Leave it there.
146
147 Let's create the first attribute: the title of the blog entry. Right-click on the entity and select **New Attribute**. Type the following values:
148
149 * **Name**: title
150 * **Column**: title
151 * **Prototype**: varchar255
152
153 When you use prototypes, you don't need to define the type (varchar, int, etc.) for the database, so by using prototypes, if you switch from a RDBMS system to another one, say from H2 to MySQL, you only need to change the JDBC connection string and bundle the EOF plugin for the RDBMS, no need to switch data types in the model.
154
155 Now, repeat the last two steps to create the other attributes for the **BlogEntry** entity, with the following values:
156
157 |=(((
158 Attribute name
159 )))|=(((
160 Column
161 )))|=(((
162 Prototype
163 )))
164 |(((
165 content
166 )))|(((
167 content
168 )))|(((
169 longtext
170 )))
171 |(((
172 creationDate
173 )))|(((
174 creationDate
175 )))|(((
176 dateTime
177 )))
178 |(((
179 lastModified
180 )))|(((
181 lastModified
182 )))|(((
183 dateTime
184 )))
185
186 If you did everything well, the list of attributes should look like this:
187
188 [[image:attach:list.png]]
189
190 You will notice that the attributes have a column with a lock in it. When a lock is present, it will use the value of that attribute for //UPDATE ... WHERE attribute = ''// statement. This is to do optimistic locking, aka to prevent data conflict when the data object was modified by two different users. Using timestamps for optimistic locking is not a good idea because for certain RDBMS, the value can be different because of milliseconds, so remove the locks on the **creationDate** attribute. The final list should look like this:
191
192 Next step is to create the **Author** entity. Create a new entity with **Author** at its name (and also as the table name), and for the class name, use **your.app.model.Author**. The attributes for this entity are:
193
194 |=(((
195 Attribute name
196 )))|=(((
197 Column
198 )))|=(((
199 Prototype
200 )))
201 |(((
202 firstName
203 )))|(((
204 firstName
205 )))|(((
206 varchar50
207 )))
208 |(((
209 lastName
210 )))|(((
211 lastName
212 )))|(((
213 varchar50
214 )))
215 |(((
216 email
217 )))|(((
218 email
219 )))|(((
220 varchar100
221 )))
222
223 Final list of attributes should look like this:
224
225 [[image:attach:list.png]]
226
227 Now, it's time to link the two entities together. An Author can have multiple blog entries, and a BlogEntry can only have one author. To create the relationship (the join), right-click on **Author** and select **New Relationship**. On your right, select **BlogEntry** in the list. On your left, select **to many BlogEntries**, and on your right, select **to one Author**. Now, in BlogEntry, we need to store the primary key of the author so that we can make the join. The relationship builder allow us to add that attribute, so make sure **and a new foreign key named** is checked (it is checked by default). The **Create Relationship** pane should look like this:
228
229 If you check in the **Outline** tab, you should see that **Author** now have a **blogEntries** relationship, and **BlogEntry** have a **author** relationship.
230
231 You are now ready to save the model. Save it (File -> Save) and close the **Entity Modeler** window. If you open the **Sources** in the main Eclipse window, you will notice that the **Sources** folder contains a package named **your.app.model**. (If this folder doesn't appear, you may need to set your preferences to automatically generate these source files; see the second suggestion on [[http:~~/~~/wiki.wocommunity.org/display/documentation/Useful+Eclipse+or+WOLips+Preferences>>url:http://wiki.wocommunity.org/display/documentation/Useful+Eclipse+or+WOLips+Preferences||rel="nofollow" shape="rect" class="external-link"]].)
232
233 That package have four Java classes: **_Author**, **Author**, **_BlogEntry** and **BlogEntry**. Those classes were generated by Veogen, a templating engine build on Velocity. The two classes that starts with a underscore are recreated every time you change the EOModel, so if you want to change something in those classes, you need to change the template (no need for that right now). But you can change freely the two classes that don't have the underscore, and this is what we will be doing.
234
235 What we are going to do is to write a simple method that returns the full name of an author, e.g. a method that simply concatenate the first name, a space and the last name of the author. To do so, double-click on **Author.java** and add the following methods:
236
237 {{code}}
238 public String fullName() {
239 return this.firstName() + " " + this.lastName();
240 }
241
242 {{/code}}
243
244 Nothing fancy here. Now open **BlogEntry.java** and add the following method:
245
246 {{code}}
247 @Override
248 public void awakeFromInsertion(EOEditingContext editingContext) {
249 super.awakeFromInsertion(editingContext);
250 NSTimestamp now = new NSTimestamp();
251 setCreationDate(now);
252 setLastModified(now);
253 }
254
255 {{/code}}
256
257 Why are we adding this? **awakeFromInsertion** is a very good way of setting default values when creating a new instance of a Enterprise Object (EO). In this case, we want to set automatically the creation and last modification dates without having the user to add those values.
258
259 Now, let's use migrations to actually create the database.
260
261 == Using migrations ==
262
263 Migrations allow you to create the tables and columns (and some types of constraint). **Entity Modeler** has support to generate the code for the first migration, which is called "migration 0". To do that, open the EOModel (**BlogModel EOModel** in the **Resources** folder), right-click on the model name and select **Generate Migration**.
264
265 Copy the generated code in the clipboard. Close **Entity Modeler** and in the main Eclipse window, right-click on **Sources**, select **New** and select **Class**.
266
267 Type **your.app.model.migrations** as the package and **BlogModel0** as the name of the class. Click **Finish**.
268
269 In the **Sources** folder, open the **your.app.model.migrations** package, a class named **BlogModel0** should be there. Delete everything in that file **EXCEPT** the first line (which should be //package your.app.model.migrations//) and paste the code that was generated by **Entity Modeler**. Save the file.
270
271 One last step: migrations are disabled by default. To enable them, you need to uncomment two properties in the **Properties** file that is located in the **Resources** folder. Open that file (double-click on it).
272
273 Remove the pound char in front of those two properties:
274
275 {{code}}
276 #er.migration.migrateAtStartup=true
277 #er.migration.createTablesIfNecessary=true
278
279 {{/code}}
280
281 After removing the pound char, the two properties should look like this:
282
283 {{code}}
284 er.migration.migrateAtStartup=true
285 er.migration.createTablesIfNecessary=true
286
287 {{/code}}
288
289 You are now ready to start the application so that it creates the database! To do so, right-click on **Application.java** (in the **your.app** folder) and select **Run As** -> **WOApplication**. In Eclipse's Console tab, you should see some output, including something similar to:
290
291 {{code}}
292 BlogRest[62990] INFO er.extensions.migration.ERXMigrator - Upgrading BlogModel to version 0 with migration 'your.app.model.migrations.BlogModel0@4743bf3d'
293 BlogRest[62990] INFO er.extensions.jdbc.ERXJDBCUtilities - Executing CREATE TABLE Author(email VARCHAR(100) NOT NULL, firstName VARCHAR(50) NOT NULL, id INTEGER NOT NULL, lastName VARCHAR(50) NOT NULL)
294 BlogRest[62990] INFO er.extensions.jdbc.ERXJDBCUtilities - Executing ALTER TABLE Author ADD PRIMARY KEY (id)
295 BlogRest[62990] INFO er.extensions.jdbc.ERXJDBCUtilities - Executing CREATE TABLE BlogEntry(authorID INTEGER NOT NULL, content TIMESTAMP NOT NULL, creationDate TIMESTAMP NOT NULL, id INTEGER NOT NULL, title VARCHAR(255) NOT NULL)
296 BlogRest[62990] INFO er.extensions.jdbc.ERXJDBCUtilities - Executing ALTER TABLE BlogEntry ADD PRIMARY KEY (id)
297 BlogRest[62990] INFO er.extensions.jdbc.ERXJDBCUtilities - Executing ALTER TABLE BlogEntry ADD CONSTRAINT "FOREIGN_KEY_BLOGENTRY_AUTHORID_AUTHOR_ID" FOREIGN KEY (authorID) REFERENCES Author (id)
298 BlogRest[62990] DEBUG NSLog - evaluateExpression: <er.h2.jdbcadaptor.ERH2PlugIn$H2Expression: "UPDATE _dbupdater SET version = ? WHERE modelname = ?" withBindings: 1:0(version), 2:"BlogModel"(modelName)>
299
300 {{/code}}
301
302 If you see this and that the application is running (it should open a window in your favorite browser), migration worked and your database have been created, congratulations! You can now stop the application (click the square red button in Eclipse's Console tab) and continue to the next step.
303
304 = Creating REST controllers and routes =
305
306 Project Wonder contains a framework called ERRest, which follow the same patterns as Ruby on Rails REST concepts. Using REST-style URLs is perfect for building a public blog and to create REST services to manage posting over HTTP with JSON, XML or other formats.
307
308 By default, a REST route in ERRest will generate a link like this:
309
310 {{code}}
311 /cgi-bin/WebObjects/AppName.woa/ra/EntityName/id
312 {{/code}}
313
314 So for our case, to get the first blog posting from BlogRest, the URL will look like this:
315
316 {{code}}
317 /cgi-bin/WebObjects/BlogRest.woa/ra/blogEntries/1.html
318 {{/code}}
319
320 {{info}}
321 You can shorten the URL by using mod_rewrite in Apache httpd
322 {{/info}}
323
324 == Creating controllers ==
325
326 ERRest needs controllers to act as a broker between working with the objects and the routes. So let's create a controller for BlogEntry.
327
328 Create a Java class named **BlogEntryController**, in the **your.app.rest.controllers** package, that will extend from **er.rest.routes.ERXDefaultRouteController**. Click **Finish**.
329
330 When you extend from **ERXDefaultRouteController**, a bunch of methods are added to the subclass. Let's see what they are for.
331
332 * **updateAction**: to update a specific instance of BlogEntry
333 * **destroyAction**: to delete a specific instance of BlogEntry
334 * **showAction**: to get one specific instance of BlogEntry
335 * **createAction**: to create a new object (a new instance of BlogEntry)
336 * **indexAction**: to list all (or a sublist) of the objects.
337
338 {{info}}
339 In Project Wonder, **Action** at the end of a method is a convention for REST and Direct Actions, when you call those methods from certain components, you don't need to add the **Action** part.
340 {{/info}}
341
342 For this tutorial, we will implement the **createAction** and **indexAction** methods. But first, we need to create a key filter. A key filter will... filter the input and the output of REST request so that you don't have to send all attributes for a blog entry. For example, we want to show the details for an author, but we don't want to show the password for the author (in real-life, the password would be encrypted)!
343
344 Add this method in **BlogEntryController**:
345
346 {{code}}
347 protected ERXKeyFilter filter() {
348 ERXKeyFilter personFilter = ERXKeyFilter.filterWithAttributes();
349 personFilter.setAnonymousUpdateEnabled(true);
350
351 ERXKeyFilter filter = ERXKeyFilter.filterWithAttributes();
352 filter.include(BlogEntry.AUTHOR, personFilter);
353 filter.setUnknownKeyIgnored(true);
354
355 return filter;
356 }
357
358 {{/code}}
359
360 Now, let's implement the **createAction** method:
361
362 {{code}}
363 public WOActionResults createAction() throws Throwable {
364 BlogEntry entry = create(filter());
365 editingContext().saveChanges();
366 return response(entry, filter());
367 }
368
369 {{/code}}
370
371 In 3 lines of code, you can create an object based on the request, save the new object to the database and return the new object in the response. Not bad, eh?
372
373 Last step in the controller: implementing the **indexAction** method. Again, the code is simple:
374
375 {{code}}
376 public WOActionResults indexAction() throws Throwable {
377 NSArray<BlogEntry> entries = BlogEntry.fetchAllBlogEntries(editingContext());
378 return response(entries, filter());
379 }
380
381 {{/code}}
382
383 That code simply fetch all blog entries and return them in the response.
384
385 We can now go to the next step: adding the routes.
386
387 == Adding the routes ==
388
389 A route in ERRest is simply a way to define the URL for the entities and to specify which controller the route should use. When your controller extends from **ERXDefaultRouteController**, it's easy to register a controller and a route. In **Application.java**, in the **Application** constructor, add the following code:
390
391 {{code}}
392 ERXRouteRequestHandler restRequestHandler = new ERXRouteRequestHandler();
393 restRequestHandler.addDefaultRoutes(BlogEntry.ENTITY_NAME);
394 ERXRouteRequestHandler.register(restRequestHandler);
395 setDefaultRequestHandler(restRequestHandler);
396
397 {{/code}}
398
399 The **addDefaultRoutes** method do all of the required magic, and use convention. That's why we had to name the controller **BlogEntryController**, because the convention is <EntityName>Controller.
400
401 We are now reading to add and list blog postings! Start the application and take notice of the URL. It should be something like _[[http:~~/~~/yourip:someport/cgi-bin/WebObjects/BlogRest.woa_>>url:http://youripsomeport||shape="rect"]]
402
403 == Adding posts and authors with curl ==
404
405 Since we didn't implement any HTML for our REST routes, we will create blog entries with //curl//, an open source HTTP client that is bundled with Mac OS X (you can use another client, like wget, if you like too). So let's create a blog entry.
406
407 To create a blog entry, you need to use the POST HTTP method. We will use JSON as the format since it's a bit less chatty than XML. So if the URL to the application is //[[http:~~/~~/192.168.0.102:52406/cgi-bin/WebObjects/BlogRest.woa_>>url:http://192.168.0.102:52406/cgi-bin/WebObjects/BlogRest.woa_||shape="rect"]], the full _curl// command will be:
408
409 {{code}}
410 curl -X POST -v -d '{ "title": "First post", "content": "Some text", "author": { "firstName": "Pascal", "lastName": "Robert", "email": "probert@macti.ca" } }' http://192.168.0.102:52406/cgi-bin/WebObjects/BlogRest.woa/ra/blogEntries.json
411 {{/code}}
412
413 The response should look this:
414
415 {{code}}
416 HTTP/1.0 201 Apple WebObjects
417 Content-Length: 249
418 x-webobjects-loadaverage: 0
419 Content-Type: application/json
420
421 {"id":1,"type":"BlogEntry","content":"Some text","creationDate":"2011-12-27T21:59:08Z","title":"First post","author":{"id":1,"type":"Author","email":"probert@macti.ca","firstName":"Pascal","lastName":"Robert"}}
422
423 {{/code}}
424
425 To get a list of blog entries:
426
427 {{code}}
428 curl -X GET http://192.168.0.102:52406/cgi-bin/WebObjects/BlogRest.woa/ra/blogEntries.json
429
430 {{/code}}
431
432 You can stop the application and proceed to the next step.
433
434 == Adding HTML views for blog posts ==
435
436 Now, let's build a HTML view for blog posts (you don't want your readers to get your posts by JSON, right?). Again, we will use convention to make it work easily. Open up **BlogEntryController** and add the following method:
437
438 {{code}}
439 @Override
440 protected boolean isAutomaticHtmlRoutingEnabled() {
441 return true;
442 }
443
444 {{/code}}
445
446 Switching the return value of this method says that we will follow a certain convention for HTML components. The convention for automatic HTML routing is that the component should be named <EntityName><Action>Page.wo. So in our case, the component will be **BlogEntryIndexPage**. Right-click on the project name in Eclipse and select **New** -> **WOComponent**. Change the name to **BlogEntryIndexPage** and check the **Create HTML contents** button. Click **Finish**.
447
448 The next step to get it to work is to make **BlogEntryIndexPage** to implement the **er.rest.routes.IERXRouteComponent** interface.
449
450 {{code}}
451 import er.rest.routes.IERXRouteComponent;
452
453 public class BlogEntryIndexPage extends WOComponent implements IERXRouteComponent {
454
455 {{/code}}
456
457 So now, the automatic HTML routing will send the request for **ra/blogEntries.html** to the **BlogEntryIndexPage** component. But we don't have any content in this component, so let's make a method to fetch all blog entries per creation date in descending order. So in **BlogEntryIndexPage.java**, add the following method:
458
459 {{code}}
460 public NSArray<BlogEntry> entries() {
461 EOEditingContext ec = ERXEC.newEditingContext();
462 return BlogEntry.fetchAllBlogEntries(ec, BlogEntry.CREATION_DATE.descs());
463 }
464
465 {{/code}}
466
467 We need to use that method in a WORepetition, and for that loop, we need a BlogEntry variable to iterate in the list, so add the following code to **BlogEntryIndexPage.java**:
468
469 {{code}}
470 private BlogEntry entryItem;
471
472 public BlogEntry entryItem() {
473 return entryItem;
474 }
475
476 public void setEntryItem(BlogEntry entryItem) {
477 this.entryItem = entryItem;
478 }
479
480 {{/code}}
481
482 The Java part is done, so let's add the loop inside the component. Open **BlogEntryIndexPage.wo** (it's located in the **Component** folder) and right after the <body> tag, add:
483
484 {{code}}
485 <wo:loop list="$entries" item="$entryItem">
486 <p><wo:str value="$entryItem.title" /></p>
487 <p><wo:str value="$entryItem.author.fullName" /></p>
488 </wo:loop>
489
490 {{/code}}
491
492 That component code will loop over the blog entries and display the title of the entry + the name of the author. Save everything and run the application.
493
494 If you go to [[http:~~/~~/192.168.0.102:52406/cgi-bin/WebObjects/BlogRest.woa/ra/blogEntries.html>>url:http://192.168.0.102:52406/cgi-bin/WebObjects/BlogRest.woa/ra/blogEntries.html||shape="rect"]], you will see the list of blog entries!
495
496 Now that we have a list of blog entries, let's make a page to show the content of a blog entry. Create a new component named **BlogEntryShowPage**.
497
498 Open **BlogEntryShowPage.java** and make sure the class implements **er.rest.routes.IERXRouteComponent**.
499
500 {{code}}
501 import er.rest.routes.IERXRouteComponent;
502
503 public class BlogEntryShowPage extends WOComponent implements IERXRouteComponent {
504
505 {{/code}}
506
507 We need to add other methods to receive the BlogEntry object from the controller. In **BlogEntryShowPage.java**, add:
508
509 {{code}}
510 private BlogEntry blogEntry;
511
512 @ERXRouteParameter
513 public void setBlogEntry(BlogEntry blogEntryFromController) {
514 this.blogEntry = blogEntryFromController;
515 }
516
517 public BlogEntry blogEntry() {
518 return this.blogEntry;
519 }
520
521 {{/code}}
522
523 The **@ERXRouteParameter** annotation tells the REST framework that it can automatically receive an object from the controller. And again, it's convention at work. You have to use the annotation and the setter name should be //set<EntityName>//, so for a BlogEntry, it's //setBlogEntry//, for a Author, it will be //setAuthor//.
524
525 The Java part of the work is done, so save the Java class. It's time to work on the component part. Open **BlogEntryShowPage.wo** and between the <body></body> part, add:
526
527 {{code}}
528 <h1><wo:str value="$blogEntry.title" /></h1>
529 <p><wo:str value="$blogEntry.content" /></p>
530 <p>Created on: <wo:str value="$blogEntry.creationDate" dateformat="%Y/%m/%d" /></p>
531 <p>Added by: <wo:str value="$blogEntry.author.fullName" /></p>
532
533 {{/code}}
534
535 Our view component is done, the only thing remaining is a link for the blog entry list (BlogEntryIndexPage) to the view page (BlogEntryShowPage). Save **BlogEntryShowPage.wo** and open **BlogEntryIndexPage.wo**. We are going to add a link on the title, you will replace to replace this:
536
537 {{code}}
538 <p><wo:str value="$entryItem.title" /></p>
539
540 {{/code}}
541
542 with:
543
544 {{code}}
545 <p><wo:ERXRouteLink entityName="BlogEntry" record="$entryItem" action="show"><wo:str value="$entryItem.title" /></wo:ERXRouteLink></p>
546
547 {{/code}}
548
549 Save the component and run the app. Go to [[http:~~/~~/192.168.0.102:52406/cgi-bin/WebObjects/BlogRest.woa/ra/blogEntries.html>>url:http://192.168.0.102:52406/cgi-bin/WebObjects/BlogRest.woa/ra/blogEntries.html||shape="rect"]] to get the list of posts, and you should see a link on the title. Click on it, and now you get the full details of the blog entry!
550
551 The REST part of this tutorial is now complete, [[you can now move to the next part of the tutorial>>doc:Your First Framework]].