knowrob::mongo::Cursor Class Reference

#include <Cursor.h>

Inheritance diagram for knowrob::mongo::Cursor:

Public Member Functions
	Cursor (const std::shared_ptr< Collection > &collection)
	Cursor (const Cursor &)=delete
	~Cursor ()
const auto &	id ()
void	limit (unsigned int limit)
void	ascending (const char *key)
void	descending (const char *key)
void	filter (const bson_t *query_doc)
void	aggregate (const bson_t *query_doc)
bool	next (const bson_t **doc, bool ignore_empty=false)
bool	erase ()
const auto *	query () const
	Cursor (const std::shared_ptr< Collection > &collection)
	Cursor (const Cursor &)=delete
	~Cursor ()
const auto &	id ()
void	limit (unsigned int limit)
void	ascending (const char *key)
void	descending (const char *key)
void	filter (const bson_t *query_doc)
void	aggregate (const bson_t *query_doc)
bool	next (const bson_t **doc, bool ignore_empty=false)
bool	erase ()
const auto *	query () const

Detailed Description

An abstraction for MongoDB answer cursors.

Definition at line 18 of file Cursor.h.

Constructor & Destructor Documentation

Cursor() [1/4]

Cursor::Cursor ( const std::shared_ptr< Collection > &  collection )

explicit

Definition at line 15 of file Cursor.cpp.

        : collection_(collection),
          cursor_(nullptr),
          isAggregateQuery_(false),
          limit_(0) {
    query_ = bson_new();
    opts_ = bson_new();
    collection_->appendSession(opts_);
    // use pointer as id
    std::stringstream ss;
    ss << static_cast<const void *>(this);
    id_ = ss.str();
}

Cursor() [2/4]

knowrob::mongo::Cursor::Cursor ( const Cursor &  )

delete

~Cursor() [1/2]

Cursor::~Cursor

(

)

Definition at line 29 of file Cursor.cpp.

                {
    if (cursor_ != nullptr) {
        mongoc_cursor_destroy(cursor_);
        cursor_ = nullptr;
    }
    if (query_ != nullptr) {
        bson_destroy(query_);
        query_ = nullptr;
    }
    if (opts_ != nullptr) {
        bson_destroy(opts_);
        opts_ = nullptr;
    }
}

Cursor() [3/4]

knowrob::mongo::Cursor::Cursor ( const std::shared_ptr< Collection > &  collection )

explicit

Cursor() [4/4]

knowrob::mongo::Cursor::Cursor ( const Cursor &  )

delete

~Cursor() [2/2]

knowrob::mongo::Cursor::~Cursor

(

)

Member Function Documentation

aggregate() [1/2]

void Cursor::aggregate

(

const bson_t *

query_doc

)

Run an aggregation pipeline to obtain results for this Cursor.

Parameters

query_doc

Definition at line 62 of file Cursor.cpp.

                                              {
    isAggregateQuery_ = true;
    bson_concat(query_, query_doc);
}

aggregate() [2/2]

void knowrob::mongo::Cursor::aggregate

(

const bson_t *

query_doc

)

Run an aggregation pipeline to obtain results for this Cursor.

Parameters

query_doc

ascending() [1/2]

void Cursor::ascending

(

const char *

key

)

Sort results in ascending order.

Parameters

key	a field name in result documents.

Definition at line 48 of file Cursor.cpp.

                                      {
    static bson_t *doc = BCON_NEW("sort", "{", key, BCON_INT32(1), "}");
    bson_concat(opts_, doc);
}

ascending() [2/2]

void knowrob::mongo::Cursor::ascending

(

const char *

key

)

Sort results in ascending order.

Parameters

key	a field name in result documents.

descending() [1/2]

void Cursor::descending

(

const char *

key

)

Sort results in descending order.

Parameters

key	a field name in result documents.

Definition at line 53 of file Cursor.cpp.

                                       {
    static bson_t *doc = BCON_NEW("sort", "{", key, BCON_INT32(-1), "}");
    bson_concat(opts_, doc);
}

descending() [2/2]

void knowrob::mongo::Cursor::descending

(

const char *

key

)

Sort results in descending order.

Parameters

key	a field name in result documents.

erase() [1/2]

bool Cursor::erase

(

)

Erase all documents that are result documents of this Cursor.

Returns

true on success.

Definition at line 98 of file Cursor.cpp.

                   {
    bson_error_t err;
    bool success = mongoc_collection_delete_many(
            collection_->coll(), query_, opts_, nullptr /* reply */, &err);
    if (!success) {
        throw MongoException("erase_error", err);
    }
    return true;
}

erase() [2/2]

bool knowrob::mongo::Cursor::erase

(

)

Erase all documents that are result documents of this Cursor.

Returns

true on success.

filter() [1/2]

void Cursor::filter

(

const bson_t *

query_doc

)

Filter results of the getAnswerCursor by the pattern provided.

Parameters

query_doc

a query document.

Definition at line 58 of file Cursor.cpp.

                                           {
    bson_concat(query_, query_doc);
}

filter() [2/2]

void knowrob::mongo::Cursor::filter

(

const bson_t *

query_doc

)

Filter results of the getAnswerCursor by the pattern provided.

Parameters

query_doc

a query document.

id() [1/2]

const auto& knowrob::mongo::Cursor::id ( )

inline

Returns

the unique id of this Cursor.

Definition at line 29 of file Cursor.h.

{ return id_; };

id() [2/2]

const auto& knowrob::mongo::Cursor::id ( )

inline

Returns

the unique id of this Cursor.

Definition at line 29 of file Cursor.h.

{ return id_; };

limit() [1/2]

void Cursor::limit

(

unsigned int

limit

)

Limit results produced by this Cursor.

Parameters

limit

the maximum number of results.

Definition at line 44 of file Cursor.cpp.

                                     {
    limit_ = limit;
}

limit() [2/2]

void knowrob::mongo::Cursor::limit

(

unsigned int

limit

)

Limit results produced by this Cursor.

Parameters

limit

the maximum number of results.

next() [1/2]

bool Cursor::next	(	const bson_t **	doc,
		bool	ignore_empty = false
	)

Start the query if it has not been started yet and generate the next result document.

Parameters

doc	pointer to result document.
ignore_empty

Returns

true on success

Definition at line 67 of file Cursor.cpp.

                                                       {
    if (cursor_ == nullptr) {
        if (isAggregateQuery_) {
            cursor_ = mongoc_collection_aggregate(
                    collection_->coll(), MONGOC_QUERY_NONE, query_, opts_, nullptr /* read_prefs */ );
        } else {
            cursor_ = mongoc_collection_find_with_opts(
                    collection_->coll(), query_, opts_, nullptr /* read_prefs */ );
        }
        if (limit_ > 0) {
            mongoc_cursor_set_limit(cursor_, limit_);
        }
    }
    // make sure cursor has no error
    bson_error_t err1;
    if (mongoc_cursor_error(cursor_, &err1)) {
        throw MongoException("cursor_error", err1);
    }
    // get next document
    if (!mongoc_cursor_next(cursor_, doc)) {
        // make sure cursor has no error after next has been called
        bson_error_t err2;
        if (mongoc_cursor_error(cursor_, &err2)) {
            throw MongoException("cursor_error", err2);
        }
        return ignore_empty;
    } else {
        return true;
    }
}

next() [2/2]

bool knowrob::mongo::Cursor::next	(	const bson_t **	doc,
		bool	ignore_empty = false
	)

Start the query if it has not been started yet and generate the next result document.

Parameters

doc	pointer to result document.
ignore_empty

Returns

true on success

query() [1/2]

const auto* knowrob::mongo::Cursor::query ( ) const

inline

Returns

the bson_t object associated to this Cursor.

Definition at line 78 of file Cursor.h.

{ return query_; }

query() [2/2]

const auto* knowrob::mongo::Cursor::query ( ) const

inline

Returns

the bson_t object associated to this Cursor.

Definition at line 78 of file Cursor.h.

{ return query_; }

---

The documentation for this class was generated from the following files:

• build/_CPack_Packages/Linux/DEB/knowrob-2.1.0-Linux/usr/include/knowrob/storage/mongo/Cursor.h
• src/storage/mongo/Cursor.cpp