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Wiki source code of Your First Rest Project

Version 27.1 by Filippo Laurìa on 2013/07/22 12:51
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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_wlock.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 [[image:attach:list.png]]
193
194 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:
195
196 |=(((
197 Attribute name
198 )))|=(((
199 Column
200 )))|=(((
201 Prototype
202 )))
203 |(((
204 firstName
205 )))|(((
206 firstName
207 )))|(((
208 varchar50
209 )))
210 |(((
211 lastName
212 )))|(((
213 lastName
214 )))|(((
215 varchar50
216 )))
217 |(((
218 email
219 )))|(((
220 email
221 )))|(((
222 varchar100
223 )))
224
225 Final list of attributes should look like this:
226
227 [[image:attach:author_list.png]]
228
229 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:
230
231 [[image:attach:relationship.png]]
232
233 If you check in the **Outline** tab, you should see that **Author** now have a **blogEntries** relationship, and **BlogEntry** have a **author** relationship.
234
235 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"]].)
236
237 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.
238
239 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:
240
241 {{code}}
242 public String fullName() {
243 return this.firstName() + " " + this.lastName();
244 }
245
246 {{/code}}
247
248 Nothing fancy here. Now open **BlogEntry.java** and add the following method:
249
250 {{code}}
251 @Override
252 public void awakeFromInsertion(EOEditingContext editingContext) {
253 super.awakeFromInsertion(editingContext);
254 NSTimestamp now = new NSTimestamp();
255 setCreationDate(now);
256 setLastModified(now);
257 }
258
259 {{/code}}
260
261 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.
262
263 Now, let's use migrations to actually create the database.
264
265 == Using migrations ==
266
267 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**.
268
269 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**.
270
271 Type **your.app.model.migrations** as the package and **BlogModel0** as the name of the class. Click **Finish**.
272
273 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.
274
275 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).
276
277 Remove the pound char in front of those two properties:
278
279 {{code}}
280 #er.migration.migrateAtStartup=true
281 #er.migration.createTablesIfNecessary=true
282
283 {{/code}}
284
285 After removing the pound char, the two properties should look like this:
286
287 {{code}}
288 er.migration.migrateAtStartup=true
289 er.migration.createTablesIfNecessary=true
290
291 {{/code}}
292
293 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:
294
295 {{code}}
296 BlogRest[62990] INFO er.extensions.migration.ERXMigrator - Upgrading BlogModel to version 0 with migration 'your.app.model.migrations.BlogModel0@4743bf3d'
297 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)
298 BlogRest[62990] INFO er.extensions.jdbc.ERXJDBCUtilities - Executing ALTER TABLE Author ADD PRIMARY KEY (id)
299 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)
300 BlogRest[62990] INFO er.extensions.jdbc.ERXJDBCUtilities - Executing ALTER TABLE BlogEntry ADD PRIMARY KEY (id)
301 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)
302 BlogRest[62990] DEBUG NSLog - evaluateExpression: <er.h2.jdbcadaptor.ERH2PlugIn$H2Expression: "UPDATE _dbupdater SET version = ? WHERE modelname = ?" withBindings: 1:0(version), 2:"BlogModel"(modelName)>
303
304 {{/code}}
305
306 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.
307
308 = Creating REST controllers and routes =
309
310 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.
311
312 By default, a REST route in ERRest will generate a link like this:
313
314 {{code}}
315 /cgi-bin/WebObjects/AppName.woa/ra/EntityName/id
316 {{/code}}
317
318 So for our case, to get the first blog posting from BlogRest, the URL will look like this:
319
320 {{code}}
321 /cgi-bin/WebObjects/BlogRest.woa/ra/blogEntries/1.html
322 {{/code}}
323
324 {{info}}
325 You can shorten the URL by using mod_rewrite in Apache httpd
326 {{/info}}
327
328 == Creating controllers ==
329
330 ERRest needs controllers to act as a broker between working with the objects and the routes. So let's create a controller for BlogEntry.
331
332 Create a Java class named **BlogEntryController**, in the **your.app.rest.controllers** package, that will extend from **er.rest.routes.ERXDefaultRouteController**. Click **Finish**.
333
334 When you extend from **ERXDefaultRouteController**, a bunch of methods are added to the subclass. Let's see what they are for.
335
336 * **updateAction**: to update a specific instance of BlogEntry
337 * **destroyAction**: to delete a specific instance of BlogEntry
338 * **showAction**: to get one specific instance of BlogEntry
339 * **createAction**: to create a new object (a new instance of BlogEntry)
340 * **indexAction**: to list all (or a sublist) of the objects.
341
342 {{info}}
343 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.
344 {{/info}}
345
346 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)!
347
348 Add this method in **BlogEntryController**:
349
350 {{code}}
351 protected ERXKeyFilter filter() {
352 ERXKeyFilter personFilter = ERXKeyFilter.filterWithAttributes();
353 personFilter.setAnonymousUpdateEnabled(true);
354
355 ERXKeyFilter filter = ERXKeyFilter.filterWithAttributes();
356 filter.include(BlogEntry.AUTHOR, personFilter);
357 filter.setUnknownKeyIgnored(true);
358
359 return filter;
360 }
361
362 {{/code}}
363
364 Now, let's implement the **createAction** method:
365
366 {{code}}
367 public WOActionResults createAction() throws Throwable {
368 BlogEntry entry = create(filter());
369 editingContext().saveChanges();
370 return response(entry, filter());
371 }
372
373 {{/code}}
374
375 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?
376
377 Last step in the controller: implementing the **indexAction** method. Again, the code is simple:
378
379 {{code}}
380 public WOActionResults indexAction() throws Throwable {
381 NSArray<BlogEntry> entries = BlogEntry.fetchAllBlogEntries(editingContext());
382 return response(entries, filter());
383 }
384
385 {{/code}}
386
387 That code simply fetch all blog entries and return them in the response.
388
389 We can now go to the next step: adding the routes.
390
391 == Adding the routes ==
392
393 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:
394
395 {{code}}
396 ERXRouteRequestHandler restRequestHandler = new ERXRouteRequestHandler();
397 restRequestHandler.addDefaultRoutes(BlogEntry.ENTITY_NAME);
398 ERXRouteRequestHandler.register(restRequestHandler);
399 setDefaultRequestHandler(restRequestHandler);
400
401 {{/code}}
402
403 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.
404
405 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"]]
406
407 == Adding posts and authors with curl ==
408
409 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.
410
411 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:
412
413 {{code}}
414 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
415 {{/code}}
416
417 The response should look this:
418
419 {{code}}
420 HTTP/1.0 201 Apple WebObjects
421 Content-Length: 249
422 x-webobjects-loadaverage: 0
423 Content-Type: application/json
424
425 {"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"}}
426
427 {{/code}}
428
429 To get a list of blog entries:
430
431 {{code}}
432 curl -X GET http://192.168.0.102:52406/cgi-bin/WebObjects/BlogRest.woa/ra/blogEntries.json
433
434 {{/code}}
435
436 You can stop the application and proceed to the next step.
437
438 == Adding HTML views for blog posts ==
439
440 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:
441
442 {{code}}
443 @Override
444 protected boolean isAutomaticHtmlRoutingEnabled() {
445 return true;
446 }
447
448 {{/code}}
449
450 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**.
451
452 The next step to get it to work is to make **BlogEntryIndexPage** to implement the **er.rest.routes.IERXRouteComponent** interface.
453
454 {{code}}
455 import er.rest.routes.IERXRouteComponent;
456
457 public class BlogEntryIndexPage extends WOComponent implements IERXRouteComponent {
458
459 {{/code}}
460
461 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:
462
463 {{code}}
464 public NSArray<BlogEntry> entries() {
465 EOEditingContext ec = ERXEC.newEditingContext();
466 return BlogEntry.fetchAllBlogEntries(ec, BlogEntry.CREATION_DATE.descs());
467 }
468
469 {{/code}}
470
471 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**:
472
473 {{code}}
474 private BlogEntry entryItem;
475
476 public BlogEntry entryItem() {
477 return entryItem;
478 }
479
480 public void setEntryItem(BlogEntry entryItem) {
481 this.entryItem = entryItem;
482 }
483
484 {{/code}}
485
486 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:
487
488 {{code}}
489 <wo:loop list="$entries" item="$entryItem">
490 <p><wo:str value="$entryItem.title" /></p>
491 <p><wo:str value="$entryItem.author.fullName" /></p>
492 </wo:loop>
493
494 {{/code}}
495
496 That component code will loop over the blog entries and display the title of the entry + the name of the author. Save everything and run the application.
497
498 If you go to [[http:~~/~~/192.168.0.102:52406/cgi-bin/WebObjects/BlogRest.woa/ra/blogEntries.html>>url:http://192.168.0.102:52406/cgi-bin/WebObjects/BlogRest.woa/ra/blogEntries.html||shape="rect"]], you will see the list of blog entries!
499
500 Now that we have a list of blog entries, let's make a page to show the content of a blog entry. Create a new component named **BlogEntryShowPage**.
501
502 Open **BlogEntryShowPage.java** and make sure the class implements **er.rest.routes.IERXRouteComponent**.
503
504 {{code}}
505 import er.rest.routes.IERXRouteComponent;
506
507 public class BlogEntryShowPage extends WOComponent implements IERXRouteComponent {
508
509 {{/code}}
510
511 We need to add other methods to receive the BlogEntry object from the controller. In **BlogEntryShowPage.java**, add:
512
513 {{code}}
514 private BlogEntry blogEntry;
515
516 @ERXRouteParameter
517 public void setBlogEntry(BlogEntry blogEntryFromController) {
518 this.blogEntry = blogEntryFromController;
519 }
520
521 public BlogEntry blogEntry() {
522 return this.blogEntry;
523 }
524
525 {{/code}}
526
527 The **@ERXRouteParameter** annotation tells the REST framework that it can automatically receive an object from the controller. And again, it's convention at work. You have to use the annotation and the setter name should be //set<EntityName>//, so for a BlogEntry, it's //setBlogEntry//, for a Author, it will be //setAuthor//.
528
529 The Java part of the work is done, so save the Java class. It's time to work on the component part. Open **BlogEntryShowPage.wo** and between the <body></body> part, add:
530
531 {{code}}
532 <h1><wo:str value="$blogEntry.title" /></h1>
533 <p><wo:str value="$blogEntry.content" /></p>
534 <p>Created on: <wo:str value="$blogEntry.creationDate" dateformat="%Y/%m/%d" /></p>
535 <p>Added by: <wo:str value="$blogEntry.author.fullName" /></p>
536
537 {{/code}}
538
539 Our view component is done, the only thing remaining is a link for the blog entry list (BlogEntryIndexPage) to the view page (BlogEntryShowPage). Save **BlogEntryShowPage.wo** and open **BlogEntryIndexPage.wo**. We are going to add a link on the title, you will replace to replace this:
540
541 {{code}}
542 <p><wo:str value="$entryItem.title" /></p>
543
544 {{/code}}
545
546 with:
547
548 {{code}}
549 <p><wo:ERXRouteLink entityName="BlogEntry" record="$entryItem" action="show"><wo:str value="$entryItem.title" /></wo:ERXRouteLink></p>
550
551 {{/code}}
552
553 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!
554
555 The REST part of this tutorial is now complete, [[you can now move to the next part of the tutorial>>doc:Your First Framework]].