Feature Representation

In addition to the generic FME feature attributes that FME Workbench adds to all features (see About Feature Attributes), this format adds the format-specific attributes described in this section.

Attribute Name Contents
couchdb_id

This format attribute is the alphanumeric ID for the document which represents the feature on the CouchDB server. This ID is unique among all features of a given feature type.

Input features that do not have a couchdb_id attribute will be assigned a unique ID by CouchDB. You must ensure that any user-specified IDs are globally-unique on the CouchDB server.

Note: The couchdb_id attribute is not modifiable once the document has been created.

couchdb_rev (read only)

This format attribute is the revision ID for the last time the server’s document was modified expressed as a hexadecimal string.

The couchdb_rev attribute of a CouchDB document is ­­­­regenerated each time the document is edited (including modifications to the couchdb_rev attribute). Because of this, you cannot set the couchdb_rev attribute.

couchdb_raw_json

This format attribute represents the document as serialized JSON.

If Read Original JSON Document is enabled on the reader, output features will contain the serialized JSON in this attribute.

CouchDB attributes cannot have names that contain non-ASCII characters; however, the attribute values support full UTF-8.

The CouchDB attribute type mapping is as follows.

CouchDB Attribute Type FME Attribute Type

string(width)

fme_varchar(width)

string(width)

fme_char(width)

string(255)

fme_buffer

string(1)

fme_char

real(width, decimal)

fme_decimal(width, decimal)

string(24)

fme_datetime

string(8)

fme_date

string(10)

fme_time

integer

fme_int32

real(10,0)

fme_uint32

real(20,0)

fme_int64

real(20,0)

fme_uint64

integer

fme_int16

integer

fme_uint16

integer

fme_uint8

real(15,7)

fme_real32

real(31,15)

fme_real64

integer

fme_boolean

Geometry

The geometry of CouchDB features may be identified by the wkb_type attribute. The valid values for this attribute are:

couchdb_type Description
wkb_none FME Feature with no geometry
wkb_point 2D Point feature
wkb_point_xyz 2.5D Point feature
wkb_line 2D Linear feature
wkb_line_xyz 2.5D Linear feature
wkb_polygon 2D Simple polygon or donut feature
wkb_polygon 2.5D Simple polygon or donut feature
wkb_geometry_collection 2D Feature with multiple geometries
wkb_geometry_collection_xyz 2.5D Feature with multiple heterogeneous geometries
wkb_multi_point 2D Feature with multiple heterogeneous point geometries
wkb_multi_point_xyz 2.5D Feature with multiple heterogeneous point geometries
wkb_multi_line 2D Feature with multiple line geometries
wkb_multi_line_xyz 2.5D Feature with multiple line geometries
wkb_multi_polygon 2D Feature with multiple polygon geometries
wkb_multi_polygon_xyz 2.5D Feature with multiple polygon geometries
wkb_geometry All geometries allowed
wkb_unknown All geometries allowed