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Cursor.cs
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Cursor.cs
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using System;
using System.Collections.Generic;
using System.IO;
using MongoDB.Driver.Connections;
using MongoDB.Driver.Protocol;
using MongoDB.Driver.Serialization;
namespace MongoDB.Driver.Generic
{
public class Cursor<T> : ICursor<T>
where T : class
{
private readonly Connection _connection;
private readonly Document _specOpts = new Document();
private bool _isModifiable = true;
private object _spec;
private object _fields;
private int _limit;
private QueryOptions _options;
private ReplyMessage<T> _reply;
private int _skip;
private readonly ISerializationFactory _serializationFactory = SerializationFactory.Default;
/// <summary>
/// Initializes a new instance of the <see cref = "Cursor<T>" /> class.
/// </summary>
/// <param name = "connection">The conn.</param>
/// <param name = "fullCollectionName">Full name of the collection.</param>
public Cursor(Connection connection, string fullCollectionName){
//Todo: should be internal
Id = -1;
_connection = connection;
FullCollectionName = fullCollectionName;
}
/// <summary>
/// Initializes a new instance of the <see cref = "Cursor<T>" /> class.
/// </summary>
/// <param name = "connection">The conn.</param>
/// <param name = "fullCollectionName">Full name of the collection.</param>
/// <param name = "spec">The spec.</param>
/// <param name = "limit">The limit.</param>
/// <param name = "skip">The skip.</param>
/// <param name = "fields">The fields.</param>
public Cursor(Connection connection, string fullCollectionName, object spec, int limit, int skip, object fields)
: this(connection, fullCollectionName){
//Todo: should be internal
if(spec == null)
spec = new Document();
_spec = spec;
_limit = limit;
_skip = skip;
_fields = fields;
}
/// <summary>
/// Gets or sets the full name of the collection.
/// </summary>
/// <value>The full name of the collection.</value>
public string FullCollectionName { get; private set; }
/// <summary>
/// Gets or sets the id.
/// </summary>
/// <value>The id.</value>
public long Id { get; private set; }
/// <summary>
/// Specs the specified spec.
/// </summary>
/// <param name="spec">The spec.</param>
/// <returns></returns>
public ICursor<T> Spec(Document spec){
return Spec((object)spec);
}
/// <summary>
/// Specs the specified spec.
/// </summary>
/// <param name="spec">The spec.</param>
/// <returns></returns>
public ICursor<T> Spec(object spec){
TryModify();
_spec = spec;
return this;
}
/// <summary>
/// Limits the specified limit.
/// </summary>
/// <param name="limit">The limit.</param>
/// <returns></returns>
public ICursor<T> Limit(int limit){
TryModify();
_limit = limit;
return this;
}
/// <summary>
/// Skips the specified skip.
/// </summary>
/// <param name="skip">The skip.</param>
/// <returns></returns>
public ICursor<T> Skip(int skip){
TryModify();
_skip = skip;
return this;
}
/// <summary>
/// Fieldses the specified fields.
/// </summary>
/// <param name="fields">The fields.</param>
/// <returns></returns>
public ICursor<T> Fields(Document fields){
return Fields((object)fields);
}
/// <summary>
/// Fieldses the specified fields.
/// </summary>
/// <param name="fields">The fields.</param>
/// <returns></returns>
public ICursor<T> Fields(object fields){
TryModify();
_fields = fields;
return this;
}
/// <summary>
/// Sorts the specified field.
/// </summary>
/// <param name = "field">The field.</param>
/// <returns></returns>
public ICursor<T> Sort(string field){
return Sort(field, IndexOrder.Ascending);
}
/// <summary>
/// Sorts the specified field.
/// </summary>
/// <param name = "field">The field.</param>
/// <param name = "order">The order.</param>
/// <returns></returns>
public ICursor<T> Sort(string field, IndexOrder order){
return Sort(new Document().Add(field, order));
}
/// <summary>
/// Sorts the specified fields.
/// </summary>
/// <param name="fields">The fields.</param>
/// <returns></returns>
public ICursor<T> Sort(Document fields){
return Sort((object)fields);
}
/// <summary>
/// Sorts the specified fields.
/// </summary>
/// <param name="fields">The fields.</param>
/// <returns></returns>
public ICursor<T> Sort(object fields)
{
TryModify();
AddOrRemoveSpecOpt("$orderby", fields);
return this;
}
/// <summary>
/// Hints the specified index.
/// </summary>
/// <param name = "index">The index.</param>
/// <returns></returns>
public ICursor<T> Hint(Document index){
return Hint((object)index);
}
/// <summary>
/// Hints the specified index.
/// </summary>
/// <param name="index">The index.</param>
/// <returns></returns>
public ICursor<T> Hint(object index)
{
TryModify();
AddOrRemoveSpecOpt("$hint", index);
return this;
}
/// <summary>
/// Snapshots the specified index.
/// </summary>
/// <param name = "index">The index.</param>
/// <returns></returns>
public ICursor<T> Snapshot(Document index){
return Snapshot((object)index);
}
/// <summary>
/// Snapshots the specified index.
/// </summary>
/// <param name="index">The index.</param>
/// <returns></returns>
public ICursor<T> Snapshot(object index)
{
TryModify();
AddOrRemoveSpecOpt("$snapshot", index);
return this;
}
/// <summary>
/// Explains this instance.
/// </summary>
/// <returns></returns>
public T Explain(){
//Todo: i am not sure that this will work now.
TryModify();
_specOpts["$explain"] = true;
var documents = Documents;
using((IDisposable)documents){
foreach(var document in documents)
return document;
}
throw new InvalidOperationException("Explain failed.");
}
/// <summary>
/// Gets a value indicating whether this <see cref = "Cursor<T>" /> is modifiable.
/// </summary>
/// <value><c>true</c> if modifiable; otherwise, <c>false</c>.</value>
public bool IsModifiable{
get { return _isModifiable; }
}
/// <summary>
/// Gets the documents.
/// </summary>
/// <value>The documents.</value>
public IEnumerable<T> Documents{
get{
if(_reply == null)
RetrieveData();
if(_reply == null)
throw new InvalidOperationException("Expecting reply but get null");
var documents = _reply.Documents;
var documentCount = 0;
var shouldBreak = false;
while(!shouldBreak){
foreach(var document in documents)
if((_limit == 0) || (_limit != 0 && documentCount < _limit)){
documentCount++;
yield return document;
}
else
yield break;
if(Id != 0){
RetrieveMoreData();
documents = _reply.Documents;
if(documents == null)
shouldBreak = true;
}
else
shouldBreak = true;
}
}
}
/// <summary>
/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
/// </summary>
public void Dispose(){
if(Id == 0) //All server side resources disposed of.
return;
var killCursorsMessage = new KillCursorsMessage(Id);
try{
_connection.SendMessage(killCursorsMessage);
Id = 0;
}
catch(IOException exception){
throw new MongoCommException("Could not read data, communication failure", _connection, exception);
}
}
/// <summary>
/// Optionses the specified options.
/// </summary>
/// <param name = "options">The options.</param>
/// <returns></returns>
public ICursor<T> Options(QueryOptions options){
TryModify();
_options = options;
return this;
}
/// <summary>
/// Retrieves the data.
/// </summary>
private void RetrieveData(){
var descriptor = _serializationFactory.GetBsonDescriptor(typeof(T), _connection);
var query = new QueryMessage<T>(descriptor){
FullCollectionName = FullCollectionName,
Query = BuildSpec(),
NumberToReturn = _limit,
NumberToSkip = _skip,
Options = _options
};
if(_fields != null)
query.ReturnFieldSelector = _fields;
var builder = _serializationFactory.GetBsonBuilder(typeof(T), _connection);
try{
_reply = _connection.SendTwoWayMessage<T>(query, builder);
Id = _reply.CursorId;
if(_limit < 0)
_limit = _limit*-1;
_isModifiable = false;
}
catch(IOException exception){
throw new MongoCommException("Could not read data, communication failure", _connection, exception);
}
}
/// <summary>
/// Retrieves the more data.
/// </summary>
private void RetrieveMoreData(){
var getMoreMessage = new GetMoreMessage(FullCollectionName, Id, _limit);
var builder = _serializationFactory.GetBsonBuilder(typeof(T), _connection);
try{
_reply = _connection.SendTwoWayMessage<T>(getMoreMessage, builder);
Id = _reply.CursorId;
}
catch(IOException exception){
Id = 0;
throw new MongoCommException("Could not read data, communication failure", _connection, exception);
}
}
/// <summary>
/// Tries the modify.
/// </summary>
private void TryModify(){
if(_isModifiable)
return;
throw new InvalidOperationException("Cannot modify a cursor that has already returned documents.");
}
/// <summary>
/// Adds the or remove spec opt.
/// </summary>
/// <param name = "key">The key.</param>
/// <param name = "doc">The doc.</param>
private void AddOrRemoveSpecOpt(string key, object doc){
if(doc == null)
_specOpts.Remove(key);
else
_specOpts[key] = doc;
}
/// <summary>
/// Builds the spec.
/// </summary>
/// <returns></returns>
private object BuildSpec(){
if(_specOpts.Count == 0)
return _spec;
var document = new Document();
_specOpts.CopyTo(document);
document["$query"] = _spec;
return document;
}
}
}