RoboSpice persist JSON array with OrmLite

Question

I\'m using RoboSpice with Spring for Android and would like to persist a JSON array of objects with OrmLite. GSON is used for the JSON marshalling. With the default caching

Answer 1

I struggled with this the whole of today and finally figured how to save a JSON array into a SQLite database using Robospice Spring Android without modifying the JSON.

This is my post JSON array returned from my server:

[
{
"id": "5573547af58cd75df03306cc",
"name": "Simon",
"postheader": "First Post"
},
{
"id": "55735475f58cd75df03306cb",
"name": "Tyron",
"postheader": "Second Post"
}
]

This is similar to the JSON in this question:

[{"id": 1, "title": "Test 1"},{"id": 2, "title": "Test 3"},{"id": 3, "title": "Test 3"}]

Step 1:

You will need to create 2 classes on the android side.

One will be the normal object that you want to save from the array. In my case, I have an object called "Post" and my server returns an array of "Post".

@DatabaseTable(tableName = "post")
@JsonIgnoreProperties(ignoreUnknown = true)
public class Post implements Serializable {
    @DatabaseField(id = true)
    private String id;
    @DatabaseField
    private String name;
    @DatabaseField
    private String postheader;
    @DatabaseField(foreign = true,foreignAutoCreate = true,foreignAutoRefresh = true)
    private EmbedPost posts;

The other object will be a wrapper object that wraps over the array, I called mine "EmbedPost".

@DatabaseTable
public class EmbedPost implements Serializable {
    @DatabaseField(allowGeneratedIdInsert=true, generatedId=true)
    private int ID;
    @ForeignCollectionField(eager = false)
    private Collection posts;

By defining an int called ID in my EmbedPost class, I'm effectively creating a object that if I converted to JSON would look like this:

{"id": 1, "posts": [
{
"id": "5573547af58cd75df03306cc",
"name": "Simon",
"postheader": "First Post"
},
{
"id": "55735475f58cd75df03306cb",
"name": "Tyron",
"postheader": "Second Post"
}
]}

This is effectively a JSON string that looks very similar to what Uipko used in his solution.

{ 
    "id": 1,
    "result":[{"id": 1, "title": "Test 1"},{"id": 2, "title": "Test 3"},{"id": 3, "title": "Test 3"}]
}

Step 2:

You now persist it using SpringAndroidSpiceService.

public class AndroidSpiceService extends SpringAndroidSpiceService {
    private static final int WEBSERVICES_TIMEOUT = 10000;

    @Override
    public CacheManager createCacheManager( Application application ) {
        CacheManager cacheManager = new CacheManager();
        List< Class< ? >> classCollection = new ArrayList< Class< ? >>();

        // add persisted classes to class collection
        classCollection.add(EmbedPost.class);
        classCollection.add( Post.class );
        // init
        RoboSpiceDatabaseHelper databaseHelper = new RoboSpiceDatabaseHelper( application, "sample_database.db", 3);
        InDatabaseObjectPersisterFactory inDatabaseObjectPersisterFactory = new InDatabaseObjectPersisterFactory( application, databaseHelper, classCollection );
        cacheManager.addPersister( inDatabaseObjectPersisterFactory );
        return cacheManager;
    }

    @Override
    public RestTemplate createRestTemplate() {
        RestTemplate restTemplate = new RestTemplate();
        // set timeout for requests

        HttpComponentsClientHttpRequestFactory httpRequestFactory = new HttpComponentsClientHttpRequestFactory();
        httpRequestFactory.setReadTimeout( WEBSERVICES_TIMEOUT );
        httpRequestFactory.setConnectTimeout( WEBSERVICES_TIMEOUT );
        restTemplate.setRequestFactory( httpRequestFactory );

        MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter = new MappingJackson2HttpMessageConverter();
        final List> listHttpMessageConverters = restTemplate.getMessageConverters();

        listHttpMessageConverters.add( mappingJackson2HttpMessageConverter  );
        restTemplate.setMessageConverters( listHttpMessageConverters );
        return restTemplate;
    }

}

Be sure to add both the EmbedPost.class and Post.class to your classCollection as ORMLite cannot do its work without you persisting both. You had used ForeignKeys when you wrote up your objects and these foreign keys have to tie to something so therefore both classes must persist.

If you run into trouble, try using the logcat to figure it out. You might have to read all the messages and not just the error ones. See my post here to see how to read all logcat messages:

Robospice storing object that extends ArrayList in database via Ormlite