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var doc = require('dynamodb-doc');
var dynamo = new doc.DynamoDB();
var DDB_EPISODES_TABLE = 'podcast-episodes';
/**
* PodcastEpisode represents a single podcast episode.
*
* @param {Object} episode - properties to set on the episode.
* @constructor
*/
var PodcastEpisode = module.exports = function PodcastEpisode(episode) {
for (var property in episode) {
if (episode.hasOwnProperty(property)) {
this[property] = episode[property];
}
}
};
/**
* Find an episode in DynamoDB by Id.
*
* @param {Object} id - The episode id.
* @param {Function} - Callback to call with an error or episode.
*/
PodcastEpisode.findById = function(id, callback) {
var params = {
TableName: DDB_EPISODES_TABLE,
Key: id
};
dynamo.getItem(params, function(error, data) {
if (error) {
callback(error);
return;
}
var episode = new PodcastEpisode(data.Item);
callback(null, episode);
});
}
/**
* Find all episodes for a given feed.
*
* @param {Object} feedId - The feed id.
* @param {Function} - Callback with signature function(error, episode, last)
*/
PodcastEpisode.forEachEpisode = function(feedId, callback) {
forEachEpisode(feedId, callback);
};
function forEachEpisode(feedId, callback, startKey) {
var params = {
TableName: DDB_EPISODES_TABLE,
KeyConditionExpression: "feedId = :feedId",
ExpressionAttributeValues: {
':feedId': feedId
}
};
if (startKey) {
params['ExclusiveStartKey'] = startKey;
}
dynamo.query(params, function(error, data) {
if (error != null) {
callback(error);
return;
}
var lastResponse = !data.LastEvaluatedKey;
data.Items.forEach(function(episodeData, index, array) {
var episode = new PodcastEpisode(episodeData);
var last = lastResponse && index == (array.length - 1);
callback(null, episode, last);
});
// If this is not the last set of responses, get more.
if (!lastResponse) {
forEachEpisode(feedId, callback, data.LastEvaluatedKey);
}
});
}
/**
* Find all episodes for a given feed and return them as a collection.
*
* @param {Object} feedId - The feed id.
* @param {Function} - Callback with signature function(error, episodes)
*/
PodcastEpisode.getEpisodesForFeed = function(feedId, callback) {
var episodes = [];
PodcastEpisode.forEachEpisode(feedId, function(error, episode, last) {
if (error) {
callback(error);
return;
}
episodes.append(episode);
if (last) {
callbacK(null, episodes);
}
});
};
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