CouchDB2

CouchDB2

CouchDB v2.x Python 3 interface in a single module. Also a command line tool; see below.

Most, but not all, features of this module work with CouchDB version < 2.0.

Installation

The CouchDB2 module is available at PyPi. It can be installed using pip:

$ pip install couchdb2

The module relies on requests: http://docs.python-requests.org/en/master/ and tqdm: https://tqdm.github.io/

Example code

import couchdb2

server = couchdb2.Server()   # Arguments required according to local setup
db = server.create("test")

doc1 = {"_id": "myid", "name": "mydoc", "level": 4}
db.put(doc1)
doc = db["myid"]
assert doc == doc1

doc2 = {"name": "another", "level": 0}
db.put(doc2)
print(doc2)
# {"_id": "66b5...", "_rev": "1-f3ac...", "name": "another", "level": 0}

db.put_design("mydesign", 
              {"views":
               {"name": {"map": "function (doc) {emit(doc.name, null);}"}
               }
              })
result = db.view("mydesign", "name", key="another", include_docs=True)
assert len(result) == 1
print(result[0].doc)         # Same printout as above, using OrderedDict

db.destroy()

News

• 1.12.0
  • Added progressbar to dump and undump, using tqdm.
  • Corrected bug fetching attachments with names having "weird" characters.
  • Corrected bug creating partitioned database; thanks to https://github.com/N-Vlahovic
• 1.11.0
  • Added db.changes(). But not adequately tested!
  • Corrected returned value from set_replicate: JSON data rather than response from requests.
  • Refactored code: Got rid of object_pairs_hook=dict in json(). response.json() on a separate line everywhere.
• 1.10.0
  • Changed to unittest for the test script. Got rid of package pytest. Added some tests.
  • Improved the documentation in source and README.
  • Fixed setup.py.
  • Added __del__ to Server class.
  • Simplified get_scheduler_docs.
  • Hid module-level functions which are just help functions for the command-line tool.
  • Removed CouchDB version >= 2.0 from some methods incorrectly marked as such.
  • Changed signatures of class Database methods __init__, create, find and explain.
• 1.9.5
  • Added __str__ to Server class.
• 1.9.4
  • Added update parameter on views; thanks to https://github.com/rbarreiro
  • Added n and q parameters when creating a database; thanks to https://github.com/elChapoSing
• 1.9.3
  • Handle get_attachment rev/If-Match issue; thanks to https://github.com/seb4itik
• 1.9.2
  • Added retrieve of conflicts; thanks to https://github.com/seb4itik
• 1.9.1
  • Added ca_file parameter for HTTPS; thanks to https://github.com/seb4itik
• 1.9.0
  • Changed put_attachment and delete_attachment to update the input doc by the new _rev value.
• 1.8.5
  • Added ids(): Return an iterator over all document identifiers.
• 1.8.4
  • Added get_bulk(ids): Get several documents in one operation.

class Server

server = Server(href="http://localhost:5984/",
                username=None, password=None,
                use_session=True, ca_file=None)

An instance of the class is a connection to the CouchDB server.

• href is the URL to the CouchDB server itself.
• username and password specify the CouchDB user account to use.
• If use_session is True, then an authenticated session is used transparently. Otherwise, the values of username and password are sent with each request.
• ca_file is a path to a file or a directory containing CAs if you need to access databases in HTTPS.

server.version

Property attribute providing the version of the CouchDB server software.

server.user_context

Property attribute providing the user context of the connection.

__str__

str(server)

Returns a simple string representation of the server interface.

__len__

len(server)

Returns the number of user-defined databases.

__iter__

for db in server: ...

Returns an iterator over all user-defined databases on the server.

__getitem__

db = server[name]

Gets the named database.

__contains__

if name in server: ...

Does the named database exist?

__call__

data = server()

Returns meta information about the server.

__del__

Clean-up: Closes the requests session.

Not for explicit use; it is automatically called when the Python garbage collection mechanism deletes the instance.

server.up()

Is the server up and running, ready to respond to requests? Returns a boolean.

CouchDB version >= 2.0

server.get(name, check=True)

Gets the named database. Returns an instance of class Database.

Raises NotFoundError if check is True and the database does not exist.

server.create(name, n=3, q=8, partitioned=False)

Creates the named database. Raises CreationError if it already exists.

• name: The name of the database.
• n: The number of replicas.
• q: The number of shards.
• partitioned: Whether to create a partitioned database.

server.get_config(nodename="_local")

Gets the named node's configuration.

server.get_active_tasks()

Returns a list of running tasks.

server.get_cluster_setup(ensure_dbs_exists=None)

Returns the status of the node or cluster.

ensure_dbs_exists is a list system databases to ensure exist on the node/cluster. Defaults to ["_users","_replicator"].

CouchDB version >= 2.0

server.set_cluster_setup(doc)

Configures a node as a single node, as part of a cluster, or finalise a cluster.

See the CouchDB documentation for the contents of doc.

CouchDB version >= 2.0

server.get_membership()

Returns data about the nodes that are part of the cluster.

CouchDB version >= 2.0

server.set_replicate(doc)

Request, configure, or stop, a replication operation.

See the CouchDB documentation for the contents of doc.

server.get_scheduler_jobs(limit=None, skip=None)

Gets a list of replication jobs.

• limit: How many results to return.
• skip: How many result to skip starting at the beginning, ordered by replication ID.

server.get_scheduler_docs(limit=None, skip=None)

Gets information about replication document states.

• limit: How many results to return.
• skip: How many result to skip starting at the beginning, ordered by document ID.

server.get_node_stats(nodename="_local")

Returns statistics for the running server.

server.get_node_system(nodename="_local")

Returns various system-level statistics for the running server.

class Database

db = Database(server, name, check=True)

An instance of the class is an interface to a CouchDB database.

• server: An instance of Server.
• name: The name of the database.
• If check is True, then raise NotFoundError if the the database does not exist.

__str__

str(db)

Returns the name of the CouchDB database.

__len__

len(db)

Returns the number of documents in the database.

__contains__

if identifier in db: ...

Does a document with the given identifier exist in the database?

__iter__

for doc in db: ...

Returns an iterator over all documents in the database.

__getitem__

doc = db[id]

Returns the document with the given id.

db.exists()

Does the database exist? Returns a boolean.

db.check()

Raises NotFoundError if the database does not exist.

db.create(n=3, q=8, partitioned=False)

Creates the database. Raises CreationError if it already exists.

• n: The number of replicas.
• q: The number of shards.
• partitioned: Whether to create a partitioned database.

db.destroy()

Deletes the database and all its contents.

db.get_info()

Returns a dictionary with information about the database.

db.get_security()

Returns a dictionary with security information for the database.

db.set_security(doc)

Sets the security information for the database.

See the CouchDB documentation for the contents of doc.

db.compact(finish=False, callback=None)

Compacts the CouchDB database by rewriting the disk database file and removing old revisions of documents.

• If finish is True, then return only when compaction is done.
• In addition, if defined, the function callback(seconds) is called every second until compaction is done.

db.compact_design(designname)

Compacts the view indexes associated with the named design document.

db.view_cleanup()

Removes unnecessary view index files due to changed views in design documents of the database.

db.get(id, default=None, rev=None, revs_info=False, conflicts=False)

Returns the document with the given identifier, or the default value if not found.

• rev: Retrieves document of specified revision, if specified.
• revs_info: Whether to include detailed information for all known document revisions.
• conflicts: Whether to include information about conflicts in the document in the _conflicts attribute.

db.get_bulk(ids)

Gets several documents in one operation, given a list of document identifiers, each of which is a string (the document _id), or a tuple of the document (_id, _rev).

Returns a list of documents. If no document is found for a specified _id or (_id, _rev), None is returned in that slot of the list.

db.ids()

for identifier in db.ids(): ...

Returns an iterator over all document identifiers.

db.put(doc)

Inserts or updates the document.

If the document is already in the database, the _rev item must be present in the document; its value will be updated.

If the document does not contain an item _id, it is added having a UUID4 hex value. The _rev item will also be added.

db.update(docs)

Performs a bulk update or insertion of the given documents using a single HTTP request.

Returns an iterable (list) over the resulting documents.

docs is a sequence of dictionaries or Document objects, or objects providing an items() method that can be used to convert them to a dictionary.

The return value of this method is a list containing a tuple for every element in the docs sequence. Each tuple is of the form (success, docid, rev_or_exc), where success is a boolean indicating whether the update succeeded, docid is the ID of the document, and rev_or_exc is either the new document revision, or an exception instance (e.g. ResourceConflict) if the update failed.

If an object in the documents list is not a dictionary, this method looks for an items() method that can be used to convert the object to a dictionary.

db.delete(doc)

Deletes the document, which must contain the _id and _rev items.

db.purge(docs)

Performs purging (complete removal) of the given list of documents.

Uses a single HTTP request to purge all given documents. Purged documents do not leave any meta-data in the storage and are not replicated.

db.get_designs()

Returns the design documents for the database.

NOTE: CouchDB version >= 2.2

db.get_design(designname)

Gets the named design document.

db.put_design(designname, doc, rebuild=True)

Inserts or updates the design document under the given name.

If the existing design document is identical, no action is taken and False is returned, else the document is updated and True is returned.

If rebuild is True, force view indexes to be rebuilt after update by accessing the view. This may take some time.

Example of doc:

  {"views":
    {"name":
      {"map": "function (doc) {emit(doc.name, null);}"},
     "name_sum":
      {"map": "function (doc) {emit(doc.name, 1);}",
       "reduce": "_sum"},
     "name_count":
      {"map": "function (doc) {emit(doc.name, null);}",
       "reduce": "_count"}
  }}

More info: http://docs.couchdb.org/en/latest/api/ddoc/common.html

db.view(designname, viewname, **kwargs)

Query a view index to obtain data and/or documents.

Keyword arguments (default value is None unless specified):

• key: Return only rows that match the specified key.
• keys: Return only rows where they key matches one of those specified as a list.
• startkey: Return rows starting with the specified key.
• endkey: Stop returning rows when the specified key is reached.
• skip: Skip the number of rows before starting to return rows.
• limit: Limit the number of rows returned.
• sorted=True: Sort the rows by the key of each returned row. The items total_rows and offset are not available if set to False.
• descending=False: Return the rows in descending order.
• group=False: Group the results using the reduce function of the design document to a group or a single row. If set to True implies reduce to True and defaults the group_level to the maximum.
• group_level: Specify the group level to use. Implies group is True.
• reduce: If set to False then do not use the reduce function if there is one defined in the design document. Default is to use the reduce function if defined.
• include_docs=False: If True, include the document for each row. This will force reduce to False.
• update="true": Whether ir not the view should be updated prior to returning the result. Supported value are "true", "false" and "lazy".

Returns an instance of class ViewResult, containing the following attributes:

• rows: The list of Row objects.
• offset: The offset used for the set of rows.
• total_rows: The total number of rows selected.

A Row object contains the following attributes:

• id: The identifier of the document, if any.
• key: The key for the index row.
• value: The value for the index row.
• doc: The document, if any.

db.get_indexes()

Returns a list of all Mango indexes in the database.

CouchDB version >= 2.0

db.put_index(fields, ddoc=None, name=None, selector=None)

Stores a Mango index specification.

• fields: A list of fields to index.
• ddoc: The design document name. Generated if none given.
• name: The name of the index. Generated if none given.
• selector: A partial filter selector, which may be omitted.

Returns a dictionary with items id (design document name; sic!), name (index name) and result (created or exists).

CouchDB version >= 2.0

db.delete_index(designname, name)

Deletes the named index in the design document of the given name.

CouchDB version >= 2.0

db.find(selector, **kwargs)

data = db.find(selector, limit=25, skip=None, sort=None, fields=None,
               use_index=None, bookmark=None, update=True, conflicts=False)

Selects documents according to the Mango index selector.

• selector: The Mango index. For more information on selector syntax, see https://docs.couchdb.org/en/latest/api/database/find.html#find-selectors
• limit: Maximum number of results returned.
• skip: Skip the given number of results.
• sort: A list of dictionaries specifying the order of the results, where the field name is the key and the direction is the value; either "asc" or "desc".
• fields: List specifying which fields of each result document should be returned. If omitted, return the entire document.
• use_index: String or list of strings specifying the index(es) to use.
• bookmark: A string that marks the end the previous set of results. If given, the next set of results will be returned.
• update: Whether to update the index prior to returning the result.
• conflicts: Whether to include conflicted documents.

Returns a dictionary with items docs, warning, execution_stats and bookmark.

CouchDB version >= 2.0

db.explain(selector, **kwargs)

data = db.explain(selector, use_index=None, limit=None, skip=None,
                  sort=None, fields=None, bookmark=None)

Returns info on which index is being used by the query.

• selector: The Mango index. For more information on selector syntax, see https://docs.couchdb.org/en/latest/api/database/find.html#find-selectors
• limit: Maximum number of results returned.
• skip: Skip the given number of results.
• sort: A list of dictionaries specifying the order of the results, where the field name is the key and the direction is the value; either "asc" or "desc".
• fields: List specifying which fields of each result document should be returned. If omitted, return the entire document.
• bookmark: A string that marks the end the previous set of results. If given, the next set of results will be returned.

CouchDB version >= 2.0

db.get_attachment(doc, filename)

Returns a file-like object containing the content of the specified attachment.

db.put_attachment(doc, content, filename=None, content_type=None)

Adds or updates the given file as an attachment to the given document in the database.

• content is a string or a file-like object.
• If filename is not provided, then an attempt is made to get it from the content object. If this fails, ValueError is raised.
• If content_type is not provided, then an attempt to guess it from the filename extension is made. If that does not work, it is set to "application/octet-stream"

Returns the new revision of the document, in addition to updating the _rev field in the document.

db.delete_attachment(doc, filename)

Deletes the attachment.

Returns the new revision of the document, in addition to updating the _rev field in the document.

db.dump(filepath, callback=None, exclude_designs=False, progressbar=False)

Dumps the entire database to a tar file.

Returns a tuple (ndocs, nfiles) giving the number of documents and attached files written out.

If defined, the function callback(ndocs, nfiles) is called every 100 documents.

If exclude_designs is True, design document will be excluded from the dump.

If progressbar is True, display a progress bar.

If the filepath ends with .gz, then the tar file is gzip compressed. The _rev item of each document is included in the dump.

db.undump(filepath, callback=None, progressbar=False)

Loads the tar file given by the path. It must have been produced by db.dump.

Returns a tuple (ndocs, nfiles) giving the number of documents and attached files read from the file.

If defined, the function callback(ndocs, nfiles) is called every 100 documents.

If progressbar is True, display a progress bar.

NOTE: The documents are just added to the database, ignoring any _rev items. This means that no document with the same identifier may exist in the database.

CouchDB2Exception

The Base CouchDB2 exception, from which all others derive.

NotFoundError

No such entity (e.g. database or document) exists.

BadRequestError

Invalid request; bad name, body or headers.

CreationError

Could not create the entity; it exists already.

RevisionError

Wrong or missing _rev item in the document to save.

AuthorizationError

Current user not authorized to perform the operation.

ContentTypeError

Bad Content-Type value in the request.

ServerError

Internal CouchDB server error.

class ViewResult(rows, offset, total_rows)

An instance of this class is returned as result from db.view(). Instances of this class are not supposed to be created by client software.

Attributes:

• rows: the list of Row objects.
• offset: the offset used for the set of rows.
• total_rows: the total number of rows selected.

__len__

len(viewresult)

Return the number of rows in the view result.

__iter__

for row in viewresult: ...

Return an iterator over all rows in the view result.

__getitem__

row = viewresult[i]

Return the indexed view result row.

vr.json()

Return the view result data in a JSON-like representation.

class Row(id, key, value, doc)

Named-tuple object returned in ViewResult list attribute rows.

Attributes:

• id: the identifier of the document, if any. Alias for row[0].
• key: the key for the index row. Alias for row[1].
• value: the value for the index row. Alias for row[2].
• doc: the document, if any. Alias for row[3].

Utility functions at the module level

read_settings(filepath, settings=None)

Read the settings lookup from a JSON format file.

If settings is given, then return an updated copy of it, else copy the default settings, update, and return it.

Command line tool

The module is also a command line tool for interacting with the CouchDB server. It is installed if pip is used to install this module.

Settings for the command line tool are updated from the following sources, each in the order given and if it exists:

1. Default values are

   {
     "SERVER": "http://localhost:5984",
     "DATABASE": null,
     "USERNAME": null,
     "PASSWORD": null
   }
   

2. Read from the JSON file ~/.couchdb2 (in your home directory).
3. Read from the JSON file settings.json (in the current working directory).
4. Read from the JSON file given by command line option --settings FILEPATH.
5. From environment variables.
6. From command line arguments.

Options

To show available command options:

$ couchdb2 -h
usage: couchdb2 [options]

CouchDB v2.x command line tool, leveraging Python module CouchDB2.

optional arguments:
  -h, --help            show this help message and exit
  --settings FILEPATH   Settings file in JSON format.
  -S SERVER, --server SERVER
                        CouchDB server URL, including port number.
  -d DATABASE, --database DATABASE
                        Database to operate on.
  -u USERNAME, --username USERNAME
                        CouchDB user account name.
  -p PASSWORD, --password PASSWORD
                        CouchDB user account password.
  -q, --password_question
                        Ask for the password by interactive input.
  --ca_file FILE_OR_DIRPATH
                        File or directory containing CAs.
  -o FILEPATH, --output FILEPATH
                        Write output to the given file (JSON format).
  --indent INT          Indentation level for JSON format output file.
  -y, --yes             Do not ask for confirmation (delete, destroy, undump).
  -v, --verbose         Print more information.
  -s, --silent          Print no information.

server operations:
  -V, --version         Output CouchDB server version.
  --list                Output a list of the databases on the server.

Database operations.:
  --create              Create the database.
  --destroy             Delete the database and all its contents.
  --compact             Compact the database; may take some time.
  --compact_design DDOC
                        Compact the view indexes for the named design doc.
  --view_cleanup        Remove view index files no longer required.
  --info                Output information about the database.
  --security            Output security information for the database.
  --set_security FILEPATH
                        Set security information for the database from the
                        JSON file.
  --list_designs        List design documents for the database.
  --design DDOC         Output the named design document.
  --put_design DDOC FILEPATH
                        Store the named design document from the file.
  --delete_design DDOC  Delete the named design document.
  --dump FILEPATH       Create a dump file of the database.
  --undump FILEPATH     Load a dump file into the database.

Document operations.:
  -G DOCID, --get DOCID
                        Output the document with the given identifier.
  -P FILEPATH, --put FILEPATH
                        Store the document; arg is literal doc or filepath.
  --delete DOCID        Delete the document with the given identifier.

attachments to document:
  --attach DOCID FILEPATH
                        Attach the specified file to the given document.
  --detach DOCID FILENAME
                        Remove the attached file from the given document.
  --get_attach DOCID FILENAME
                        Get the attached file from the given document; write
                        to same filepath or that given by '-o'.

query a design view, returning rows:
  --view SPEC           Design view '{design}/{view}' to query.
  --key KEY             Key value selecting view rows.
  --startkey KEY        Start key value selecting range of view rows.
  --endkey KEY          End key value selecting range of view rows.
  --startkey_docid DOCID
                        Return rows starting with the specified document.
  --endkey_docid DOCID  Stop returning rows when specified document reached.
  --group               Group the results using the 'reduce' function.
  --group_level INT     Specify the group level to use.
  --noreduce            Do not use the 'reduce' function of the view.
  --limit INT           Limit the number of returned rows.
  --skip INT            Skip this number of rows before returning result.
  --descending          Sort rows in descending order (swap start/end keys!).
  --include_docs        Include documents in result.