CODEWITHSUNDEEP
android
Manish Kumar Sharma
Manish Kumar Sharma

Reputation: 13442

What is BUCKET_ID in MediaStore?

I was browsing through some code that queries the MediaStore.Images content provider and uses a column named BUCKET_ID:

Uri uri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
String projection[] = {
    "DISTINCT " + MediaStore.Images.Media.BUCKET_DISPLAY_NAME,
    MediaStore.Images.Media.BUCKET_ID,
    MediaStore.Images.Media.DATE_TAKEN,
    MediaStore.Images.Media.DATA
};
String BUCKET_GROUP_BY = "1) GROUP BY 1,(2";
String BUCKET_ORDER_BY = "MAX(datetaken) DESC";
Cursor imagecursor = getContentResolver().query(uri, projection, BUCKET_GROUP_BY, null, BUCKET_ORDER_BY);

In general, what do these columns represent? Can anyone explain with examples?(The docs have a one-liner about these columns that explains quite less)

Upvotes: 2

Views: 6423

Answers (2)

Nirav Joshi
Nirav Joshi

Reputation: 1723

BUCKET_DISPLAY_NAME

added to API level 29 String BUCKET_DISPLAY_NAME The bucket display name of the image. This is a read-only property that is automatically computed from the DATA column.

Type: TEXT

Constant Value: "bucket_display_name"

BUCKET_ID

added in API level 29 String BUCKET_ID The bucket id of the image. This is a read-only property that is automatically computed from the DATA column.

Type: TEXT

Constant Value: "bucket_id"

DATE_TAKEN

added to API level 29 String DATE_TAKEN The date & time that the image was taken in units of milliseconds since Jan 1, 1970.

Type: INTEGER

Constant Value: "datetaken"

Upvotes: 0

Manish Kumar Sharma
Manish Kumar Sharma

Reputation: 13442

Docs are vastly unclear on this and the above answer is a copy-paste from the docs. Anyway, I have found the answer from the source of Gallery 3D in form of comments:

    // BUCKET_DISPLAY_NAME is a string like "Camera" which is the directory
    // name of where an image or video is in. BUCKET_ID is a hash of the path
    // name of that directory (see computeBucketValues() in MediaProvider for
    // details). MEDIA_TYPE is video, image, audio, etc.
    //
    // The "albums" are not explicitly recorded in the database, but each image
    // or video has the two columns (BUCKET_ID, MEDIA_TYPE). We define an
    // "album" to be the collection of images/videos which have the same value
    // for the two columns.

and here is the computeBucketValues() for reference:

/**
     * @param data The input path
     * @param values the content values, where the bucked id name and bucket display name are updated.
     *
     */
    private static void computeBucketValues(String data, ContentValues values) {
        File parentFile = new File(data).getParentFile();
        if (parentFile == null) {
            parentFile = new File("/");
        }

        // Lowercase the path for hashing. This avoids duplicate buckets if the
        // filepath case is changed externally.
        // Keep the original case for display.
        String path = parentFile.toString().toLowerCase();
        String name = parentFile.getName();

        // Note: the BUCKET_ID and BUCKET_DISPLAY_NAME attributes are spelled the
        // same for both images and video. However, for backwards-compatibility reasons
        // there is no common base class. We use the ImageColumns version here
        values.put(ImageColumns.BUCKET_ID, path.hashCode());
        values.put(ImageColumns.BUCKET_DISPLAY_NAME, name);
}

Upvotes: 8

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