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https://github.com/khueue/prolongo

MongoDB Driver for Prolog
https://github.com/khueue/prolongo

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MongoDB Driver for Prolog

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README 

        
MongoDB Driver for Prolog

=========================



A MongoDB driver compatible with SWI-Prolog that implements basic CRUD

functionality. Several things have yet to be implemented (authentication,

GridFS, etc.), but the driver can be used for simple use cases.



## Release History



### Version 1.1.1 (2016-09-13)



* Updated implementation to be compatible with the current MongoDB

  version (currently 3.2.9). (In particular, `mongo:list_collection_names/2`

  was updated to stop using removed MongoDB functionality.)

* Tested on SWI-Prolog 7.2.3.



### Version 1.1.0 (2012-09-10)



* BSON parser is now an external dependency (separate repository).

* Updated BSON parser to handle new binary 'uuid' subtype.

* Rewritten exception handling, exceptions now follow:

  `mongo_error(DescriptionAtom, ListOfRelatedVars)`.

* Fix buggy hex_bytes/2 (used when handling object_id).

* Hopefully improved compilation on Windows (now includes stdint.h).

* Test suite can be run in parallel by separate Prolog sessions.

* Better API documentation (in the code).

* Minor performance improvements and code cleanup.

* Internal module usage rewritten.

* Now tested on MongoDB 2.2.0.

* Prepared for SWI-Prolog 6.2.0.



### Version 1.0.0 (2012-08-11)



* First real release.

* Fix issue #1 ("Two tests failing on Swi-Prolog 6.0.2").

* Add runnable example program (simple todo).



## Dependencies



* **SWI-Prolog** - Tested on Mac OS X using SWI 7.2.3.

* **MongoDB** - Tested on Mac OS X using MongoDB 3.2.9.

* **BSON parser** - Found at .



## Installation and Usage



1. Clone the BSON parser found at ,

   switch to a certain release if you like (e.g. `git checkout v1.0.0`) and

   build it according to its instructions.

2. Clone prolongo (and possibly switch to a release, `git checkout v1.0.0`).

3. Edit the path to the BSON loader script found in `load.pl`. The path

   should be relative to prolongo's root (so you don't have to edit

   anything if you clone both BSON and prolongo into the same parent

   folder).

4. Run `make` to run the tests (will also run the BSON tests). Some

   of the tests require a MongoDB instance running on localhost on the

   default port.

5. See the example below, the tests (`*.plt`) in the `src` folder as well

   as the API documentation in the source code for more usage information.



## Usage Example



A small to-do application (also found in the examples folder):



```prolog

#!/usr/bin/env swipl --quiet -O -t todo -f



% Usage: Run `examples/todo.pl` from the project root.



% Setup prolongo load paths and load the library.

:- [load].

:- use_module(mongo(mongo), []). % Empty import forces use of namespace.



todo :-

    print_welcome,

    setup_call_cleanup(

        mongo:new_connection(Connection),

        todo_run(Connection),

        mongo:free_connection(Connection)).



print_welcome :-

    format('--- Simple Todo ---~n'),

    format('Terminate input with a period.~n~n').



todo_run(Connection) :-

    mongo:get_database(Connection, 'prolongo_example_todo', Database),

    mongo:get_collection(Database, 'items', Collection),

    action(list, Collection).



action(list, Collection) :- !,

    list_items(Collection),

    new_action(Collection).

action(add, Collection) :- !,

    add_item(Collection),

    new_action(Collection).

action(delete, Collection) :- !,

    delete_item(Collection),

    new_action(Collection).

action(quit, _Collection) :- !,

    format('Bye!~n').

action(_Unknown, Collection) :-

    format('Unknown alternative.~n'),

    new_action(Collection).



new_action(Collection) :-

    format('~nEnter list/add/delete/quit: '),

    read(Action),

    action(Action, Collection).



list_items(Collection) :-

    mongo:find_all(Collection, [], [], Docs),

    print_items(Docs).



print_items(Docs) :-

    format('Id~26|Label~45|Priority~n'),

    print_items_aux(Docs).



print_items_aux([]).

print_items_aux([Doc|Docs]) :-

    bson:doc_get(Doc, '_id', object_id(Id)),

    bson:doc_get(Doc, label, Label),

    bson:doc_get(Doc, priority, Priority),

    format('~w~26|~w~45|~w~n', [Id,Label,Priority]),

    print_items_aux(Docs).



add_item(Collection) :-

    format('Label: '),

    read(Label),

    format('Priority: '),

    read(Priority),

    Doc = [label-Label,priority-Priority],

    mongo:insert(Collection, Doc).



delete_item(Collection) :-

    format('Id: '),

    read(Id),

    mongo:delete(Collection, ['_id'-object_id(Id)]).

```



Consult the file and make sure you have a MongoDB instance running on

localhost, then run it:



```

?- todo.

--- Simple Todo ---

Id                        Label              Priority



Enter list/add/delete/quit: add.

Label: 'Make tea'.

Priority: 1.



Enter list/add/delete/quit: add.

Label: 'Go for a walk'.

Priority: 2.



Enter list/add/delete/quit: list.

Id                        Label              Priority

4dff66bd4c594ffa3e17cb70  Make tea           1

4dff66eb4c594ffa3e17cb71  Go for a walk      2



Enter list/add/delete/quit: delete.

Id: '4dff66eb4c594ffa3e17cb71'.



Enter list/add/delete/quit: list.

Id                        Label              Priority

4dff66bd4c594ffa3e17cb70  Make tea           1



Enter list/add/delete/quit: quit.

Bye!

```



## Todo



* Reduce amount of arguments to CRUD predicates.



## Issues



* RequestId and ResponseId are completely ignored (set to 0) in

  mongo message headers.



## License



Licensed under the MIT license which can be found in the file

`LICENSE` in the project root.



## Coding Guidelines



* Use empty imports (use_module(mymodule, [])) in order to not

  pollute the namespace.

* Always use module prefixes (mymodule:predicate(...)) in order to

  clarify where things are coming from.

* Always use the "made-up" module prefix "core:" when calling

  built-in predicates. This is completely unnecessary, and doesn't even

  work in all cases, but I think it is a good idea as long as it doesn't

  cause any problems. This decision may need to be revised when

  compatibility between different Prologs is investigated.

* Avoid the if-then-else construct. It just looks ugly.

* Avoid disjunctions. They are ugly, and can be replaced by properly

  written helpers. Think: premises are "and", clauses are "or".

* Use cuts where appropriate, and try to keep each cut on a line by

  itself unless its placement is obvious and consistent in each clause.

  PlUnit is excellent at pointing out when tests succeed but leave

  choice points.

* Try to avoid spaces within lists and structures, but always use

  spaces between arguments.

* Predicates, atoms, etc. should use "this_naming_style" while variables

  should use "ThisNamingStyle".

* Try to stick to the PlDoc structure.

* If in doubt, consult: .