# Using the Book Search Data API

The Google Book Search Data API allows client applications to view and update Book Search content in the form of Google Data API feeds.

Your client application can use the Book Search Data API to issue full-text searches for books and to retrieve standard book information, ratings, and reviews. You can also access individual users' library collections and public reviews. Finally, your application can submit authenticated requests to enable users to create and modify library collections, ratings, labels, reviews, and other account-specific entities.

For more information on the Book Search Data API, please refer to the official PHP Developer's Guide on code.google.com.

## Authenticating to the Book Search service

You can access both public and private feeds using the Book Search Data API. Public feeds don't require any authentication, but they are read-only. If you want to modify user libraries, submit reviews or ratings, or add labels, then your client needs to authenticate before requesting private feeds. It can authenticate using either of two approaches: AuthSub proxy authentication or ClientLogin username/password authentication. Please refer to the Authentication section in the PHP Developer's Guide for more detail.

## Searching for books

The Book Search Data API provides a number of feeds that list collections of books.

The most common action is to retrieve a list of books that match a search query. To do so you create a VolumeQuery object and pass it to the Books::getVolumeFeed() method.

For example, to perform a keyword query, with a filter on viewability to restrict the results to partial or full view books, use the setMinViewability() and setQuery() methods of the VolumeQuery object. The following code snippet prints the title and viewability of all volumes whose metadata or text matches the query term "domino":

    $books = new Zend_Gdata_Books();
    $query = $books->newVolumeQuery();

    $query->setQuery('domino');
    $query->setMinViewability('partial_view');

    $feed = $books->getVolumeFeed($query);

    foreach ($feed as $entry) {
        echo $entry->getVolumeId();
        echo $entry->getTitle();
        echo $entry->getViewability();
    }

The Query class, and subclasses like VolumeQuery, are responsible for constructing feed URLs. The VolumeQuery shown above constructs a URL equivalent to the following:

    http://www.google.com/books/feeds/volumes?q=keyword&amp;min-viewability=partial

Note: Since Book Search results are public, you can issue a Book Search query without authentication.

Here are some of the most common VolumeQuery methods for setting search parameters:

setQuery(): Specifies a search query term. Book Search searches all book metadata and full text for books matching the term. Book metadata includes titles, keywords, descriptions, author names, and subjects. Note that any spaces, quotes or other punctuation in the parameter value must be URL-escaped (Use a plus (+) for a space). To search for an exact phrase, enclose the phrase in quotation marks. For example, to search for books matching the phrase "spy plane", set the q parameter to `%22spy+plane%22`. You can also use any of the advanced search operators supported by Book Search. For example, `jane+austen+-inauthor:austen` returns matches that mention (but are not authored by) Jane Austen.

setStartIndex(): Specifies the index of the first matching result that should be included in the result set. This parameter uses a one-based index, meaning the first result is 1, the second result is 2 and so forth. This parameter works in conjunction with the max-results parameter to determine which results to return. For example, to request the third set of 10 results—results 21-30—set the start-index parameter to 21 and the max-results parameter to 10. Note: This isn't a general cursoring mechanism. If you first send a query with `?start-index=1&max-results=10` and then send another query with `?start-index=11&max-results=10`, the service cannot guarantee that the results are equivalent to `?start-index=1&max-results=20`, because insertions and deletions could have taken place in between the two queries.

setMaxResults(): Specifies the maximum number of results that should be included in the result set. This parameter works in conjunction with the start-index parameter to determine which results to return. The default value of this parameter is 10 and the maximum value is 20.

setMinViewability(): Allows you to filter the results according to the books' viewability status. This parameter accepts one of three values: 'none' (the default, returning all matching books regardless of viewability), 'partial_view' (returning only books that the user can preview or view in their entirety), or 'full_view' (returning only books that the user can view in their entirety).

### Partner Co-Branded Search

Google Book Search provides Co-Branded Search, which lets content partners provide full-text search of their books from their own websites.

If you are a partner who wants to do Co-Branded Search using the Book Search Data API, you may do so by modifying the feed URL above to point to your Co-Branded Search implementation. if, for example, a Co-Branded Search is available at the following URL:

    http://www.google.com/books/p/PARTNER_COBRAND_ID?q=ball

then you can obtain the same results using the Book Search Data API at the following URL:

    http://www.google.com/books/feeds/p/PARTNER_COBRAND_ID/volumes?q=ball+-soccer

To specify an alternate URL when querying a volume feed, you can provide an extra parameter to newVolumeQuery()

    $query =
        $books->newVolumeQuery('http://www.google.com/books/p/PARTNER_COBRAND_ID');

For additional information or support, visit our Partner help center.

## Using community features

### Adding a rating

A user can add a rating to a book. Book Search uses a 1-5 rating system in which 1 is the lowest rating. Users cannot update or delete ratings.

To add a rating, add a Rating object to a VolumeEntry and post it to the annotation feed. In the example below, we start from an empty VolumeEntry object.

    $entry = new Zend_Gdata_Books_VolumeEntry();
    $entry->setId(new Zend_Gdata_App_Extension_Id(VOLUME_ID));
    $entry->setRating(new Zend_Gdata_Extension_Rating(3, 1, 5, 1));
    $books->insertVolume($entry, Zend_Gdata_Books::MY_ANNOTATION_FEED_URI);

### Reviews

In addition to ratings, authenticated users can submit reviews or edit their reviews. For information on how to request previously submitted reviews, see Retrieving annotations.

#### Adding a review

To add a review, add a Review object to a VolumeEntry and post it to the annotation feed. In the example below, we start from an existing VolumeEntry object.

    $annotationUrl = $entry->getAnnotationLink()->href;
    $review        = new Zend_Gdata_Books_Extension_Review();

    $review->setText("This book is amazing!");
    $entry->setReview($review);
    $books->insertVolume($entry, $annotationUrl);

#### Editing a review

To update an existing review, first you retrieve the review you want to update, then you modify it, and then you submit it to the annotation feed.

    $entryUrl = $entry->getId()->getText();
    $review   = new Zend_Gdata_Books_Extension_Review();

    $review->setText("This book is actually not that good!");
    $entry->setReview($review);
    $books->updateVolume($entry, $entryUrl);

### Labels

You can use the Book Search Data API to label volumes with keywords. A user can submit, retrieve and modify labels. See Retrieving annotations for how to read previously submitted labels.

#### Submitting a set of labels

To submit labels, add a Category object with the scheme `LABELS_SCHEME` to a VolumeEntry and post it to the annotation feed.

    $annotationUrl = $entry->getAnnotationLink()->href;
    $category      = new Zend_Gdata_App_Extension_Category(
        'rated',
        'http://schemas.google.com/books/2008/labels');
    $entry->setCategory(array($category));
    $books->insertVolume($entry, Zend_Gdata_Books::MY_ANNOTATION_FEED_URI);

### Retrieving annotations: reviews, ratings, and labels

You can use the Book Search Data API to retrieve annotations submitted by a given user. Annotations include reviews, ratings, and labels. To retrieve any user's annotations, you can send an unauthenticated request that includes the user's user ID. To retrieve the authenticated user's annotations, use the value me as the user ID.

    $feed = $books->getVolumeFeed(
                'http://www.google.com/books/feeds/users/USER_ID/volumes');
    <i>(or)</i>
    $feed = $books->getUserAnnotationFeed();

    // print title(s) and rating value
    foreach ($feed as $entry) {
        foreach ($feed->getTitles() as $title) {
            echo $title;
        }
        if ($entry->getRating()) {
            echo 'Rating: ' . $entry->getRating()->getAverage();
        }
    }

For a list of the supported query parameters, see the query parameters section.

### Deleting Annotations

If you retrieved an annotation entry containing ratings, reviews, and/or labels, you can remove all annotations by calling deleteVolume() on that entry.

    $books->deleteVolume($entry);

## Book collections and My Library

Google Book Search provides a number of user-specific book collections, each of which has its own feed.

The most important collection is the user's My Library, which represents the books the user would like to remember, organize, and share with others. This is the collection the user sees when accessing his or her My Library page.

### Retrieving books in a user's library

The following sections describe how to retrieve a list of books from a user's library, with or without query parameters.

You can query a Book Search public feed without authentication.

#### Retrieving all books in a user's library

To retrieve the user's books, send a query to the My Library feed. To get the library of the authenticated user, use me in place of `USER_ID`.

    $feed = $books->getUserLibraryFeed();

Note: The feed may not contain all of the user's books, because there's a default limit on the number of results returned. For more information, see the max-results query parameter in Searching for books.

#### Searching for books in a user's library

Just as you can search across all books, you can do a full-text search over just the books in a user's library. To do this, just set the appropriate paramters on the VolumeQuery object.

For example, the following query returns all the books in your library that contain the word "bear":

    $query = $books->newVolumeQuery(
        'http://www.google.com/books/feeds/users' .
        '/USER_ID/collections/library/volumes');
    $query->setQuery('bear');
    $feed = $books->getVolumeFeed($query);

For a list of the supported query parameters, see the query parameters section. In addition, you can search for books that have been labeled by the user:

    $query = $books->newVolumeQuery(
        'http://www.google.com/books/feeds/users/' .
        'USER_ID/collections/library/volumes');
    $query->setCategory(
    $query->setCategory('favorites');
    $feed = $books->getVolumeFeed($query);

### Updating books in a user's library

You can use the Book Search Data API to add a book to, or remove a book from, a user's library. Ratings, reviews, and labels are valid across all the collections of a user, and are thus edited using the annotation feed (see Using community features).

#### Adding a book to a library

After authenticating, you can add books to the current user's library.

You can either create an entry from scratch if you know the volume ID, or insert an entry read from any feed.

The following example creates a new entry and adds it to the library:

    $entry = new Zend_Gdata_Books_VolumeEntry();
    $entry->setId(new Zend_Gdata_App_Extension_Id(VOLUME_ID));
    $books->insertVolume(
        $entry,
        Zend_Gdata_Books::MY_LIBRARY_FEED_URI
    );

The following example adds an existing VolumeEntry object to the library:

    $books->insertVolume(
        $entry,
        Zend_Gdata_Books::MY_LIBRARY_FEED_URI
    );

#### Removing a book from a library

To remove a book from a user's library, call deleteVolume() on the VolumeEntry object.

    $books->deleteVolume($entry);