pathwaycom/pathway · error · ValueError

'raw' endpoint input format requires 'value' column in schem

Error message

'raw' endpoint input format requires 'value' column in schema

What it means

Raised by pw.io.http.rest_connector when the endpoint runs in 'raw' input format but the schema has no column named 'query' (QUERY_SCHEMA_COLUMN = 'query'). In raw mode Pathway reads the plain request body into a single column, which must be called 'query'; the OpenAPI plaintext schema generator then needs that column to describe the endpoint. The error message saying 'value' column is misleading — the code actually looks up the 'query' column.

Source

Thrown at python/pathway/io/http/_server.py:226

            endpoint_description["description"] = self.description
        if self.summary is not None:
            endpoint_description["summary"] = self.summary

        return {method.lower(): endpoint_description}

    def _is_method_exposed(self, method):
        return self.method_types is None or method.upper() in self.method_types

    def _add_optional_traits_if_present(self, field_description, props):
        if props.example is not None:
            field_description["example"] = props.example
        if props.description is not None:
            field_description["description"] = props.description

    def _construct_openapi_plaintext_schema(self, schema) -> dict:
        query_column = schema.columns().get(QUERY_SCHEMA_COLUMN)
        if query_column is None:
            raise ValueError(
                "'raw' endpoint input format requires 'value' column in schema"
            )
        openapi_type = _ENGINE_TO_OPENAPI_TYPE.get(query_column, "string")
        openapi_format = _ENGINE_TO_OPENAPI_FORMAT.get(query_column)
        description = {
            "type": openapi_type,
        }
        if openapi_format:
            description["format"] = openapi_format
        if query_column.has_default_value():
            description["default"] = query_column.default_value
        self._add_optional_traits_if_present(description, query_column)

        return description

    def _construct_openapi_get_request_schema(self, schema) -> list:
        parameters = []
        for name, props in schema.columns().items():

View on GitHub (pinned to fa2f74a464)

Solutions

1. If you want raw body ingestion, pass schema=None and let rest_connector build the default 'query' column.
2. If you supply a custom schema, make sure it contains a column literally named 'query' when raw format is used: pw.schema_builder({'query': pw.column_definition(dtype=str)}).
3. For structured JSON payloads, use a full custom schema with typed columns (format switches to 'custom' automatically when schema is given to rest_connector).

Example fix

# before
schema = pw.schema_builder({"value": pw.column_definition()})
# after
schema = pw.schema_builder({"query": pw.column_definition()})  # or simply schema=None

from pathway import io as pio

def has_query_column(schema) -> bool:
    return "query" in schema.columns()

def is_raw_ready_schema(schema) -> bool:
    cols = schema.columns()
    return cols is not None and "query" in cols

When it happens

Trigger: Calling pw.io.http.rest_connector(...) with schema=None triggers the built-in raw schema pw.schema_builder({'query': ...}), so this error normally does not fire from that path. It fires when a custom schema lacking a 'query' column is combined with raw-format handling, e.g. via the internal RestServerSubject with format='raw', or when a schema passed to the connector defines columns like 'value' or 'data' instead of 'query'.

Common situations: Developers porting older REST connector code that used a 'value' column name; constructing a schema with pw.schema_builder({'value': pw.column_definition()}) and expecting raw body ingestion; calling lower-level internals with a custom schema but defaulting to raw format.

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AI-assisted analysis of pathwaycom/pathway@fa2f74a464 (2026-08-15). Data as JSON: /api/errors/5801705adc1ebb79. Report an issue: GitHub.