Codecs

hl7types.codecs.er7.encoder.encode_er7_segment(seg, enc=EncodingChars(field='|', component='^', repetition='~', escape='\\', subcomponent='&', truncation=''))

Encode a single segment model to an ER7 segment string.

Parameters:

  • seg (BaseModel) – The segment model instance to encode.

  • enc (EncodingChars, optional) – Delimiter characters to use. Defaults to the standard HL7 encoding characters (|, ^, ~, \, &).

Returns:

A single ER7 segment string with no trailing separator, e.g. "MSA|AA|MSG001".

Return type:

str

Examples

>>> from hl7types.hl7.v2_5_1.segments import MSA
>>> from hl7types.codecs.er7.encoder import encode_er7_segment
>>> encode_er7_segment(MSA(msa_1="AA", msa_2="MSG001"))
'MSA|AA|MSG001'
hl7types.codecs.er7.encoder.encode_er7(model, segment_separator='\r')

Encode a message or segment model to an ER7 wire string.

Encoding characters are read from the delimiter-definition segment (MSH, FHS, or BHS) in the model if present, falling back to the standard HL7 defaults.

Parameters:

  • model (BaseModel) – The message, group, or segment model instance to encode.

  • segment_separator (str, optional) – Character used to join segments. The HL7 v2 specification mandates a carriage return (\r, ASCII 0x0D). Defaults to "\r".

Returns:

ER7-encoded wire string with segments joined by segment_separator. Returns an empty string if the model contains no encodable segments.

Return type:

str

Examples

>>> from hl7types.hl7.v2_5_1.segments import MSA
>>> from hl7types.codecs.er7.encoder import encode_er7
>>> encode_er7(MSA(msa_1="AA", msa_2="MSG001"))
'MSA|AA|MSG001'
hl7types.codecs.er7.decoder.decode_er7_segment(seg_str, seg_cls, enc=EncodingChars(field='|', component='^', repetition='~', escape='\\', subcomponent='&', truncation=''), *, strict=False)

Decode a single ER7 segment string into a typed segment model.

Parameters:

  • seg_str (str) – A single ER7 segment string, e.g. "MSA|AA|MSG001".

  • seg_cls (type[BaseModel]) – The segment model class to decode into.

  • enc (EncodingChars, optional) – Delimiter characters to use for decoding. For delimiter-definition segments (MSH, FHS, BHS), the encoding characters are read from the segment string itself and override this value. Defaults to the standard HL7 encoding characters.

  • strict (bool, optional) – If True, raises pydantic.ValidationError when required fields are absent. If False, missing required fields are filled with empty placeholder values and a UserWarning is emitted. Defaults to False.

Returns:

A validated instance of seg_cls.

Return type:

BaseModel

Raises:

pydantic.ValidationError – If strict=True and required fields are missing, or if any field value fails format validation.

Examples

>>> from hl7types.hl7.v2_5_1.segments import MSA
>>> from hl7types.codecs.er7.decoder import decode_er7_segment
>>> seg = decode_er7_segment("MSA|AA|MSG001", MSA)
>>> seg.msa_1
'AA'
hl7types.codecs.er7.decoder.decode_er7(wire, msg_cls=None, segment_separator='\r', *, strict=True, registry=None)

Decode an ER7 wire string into a typed message model.

When msg_cls is not provided, the message class is resolved automatically from MSH.9 (message type) and MSH.12 (version) in the wire string. Encoding characters are read from the delimiter-definition segment in the wire and applied consistently throughout decoding.

Parameters:

  • wire (str) – A complete ER7-encoded message string with segments separated by segment_separator.

  • msg_cls (type[BaseModel], optional) – The message model class to decode into. If None, the class is resolved dynamically from MSH.9 and MSH.12.

  • segment_separator (str, optional) – Character used to split segments. Defaults to "\r".

  • strict (bool, optional) – If True, raises pydantic.ValidationError when required fields or segments are absent. If False, missing required fields are filled with empty placeholder values and a UserWarning is emitted. Defaults to True.

  • registry (HL7Registry, optional) – Registry of custom segment and message classes. Consulted when the decoder encounters a segment or message type not present in the generated specification models.

Returns:

A validated instance of the resolved or provided message class.

Return type:

BaseModel

Raises:

  • ValueError – If the wire string is empty, no MSH segment is found, or the message type or version cannot be resolved to a known model class.

  • pydantic.ValidationError – If strict=True and required fields or segments are missing, or if any field value fails format validation.

Examples

>>> from hl7types import decode_er7
>>> wire = "MSH|^~\\&|SEND||RECV||20260101||ACK|001|P|2.5.1\rMSA|AA|001"
>>> msg = decode_er7(wire)
>>> msg.MSA.msa_1
'AA'