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graflo.architecture.query.models

Read-request models for the DB-agnostic graph query surface.

Four questions an agent asks of a live graph — which nodes, what is adjacent to this one, what is reachable from these, how many — expressed once, in logical schema names, and answered identically by every backend.

Filters are :class:FilterExpression, which already renders to AQL, Cypher, nGQL, GSQL, SQL and Python. There is no new query language here, and there is deliberately no way to pass a backend query through: Connection.execute must never be reachable from an agent-facing path, so nothing in this module carries a raw query string.

Validation raises rather than clamps. Silently reducing hops=99 to 3 hands the caller a partial answer it believes is complete — the failure mode this codebase already rejected for TigerGraph edge direction.

Attributes

Classes

AggregateQuery

Bases: GraphQuery

Count or summarise one vertex type.

Source code in graflo/architecture/query/models.py 
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class AggregateQuery(GraphQuery):
    """Count or summarise one vertex type."""

    vertex_type: str = PydanticField(...)
    function: AggregationType = PydanticField(
        default=AggregationType.COUNT, description="Aggregation to apply."
    )
    group_by: str | None = PydanticField(
        default=None, description="Property to group by. COUNT only."
    )
    aggregated_field: str | None = PydanticField(
        default=None,
        description="Property to aggregate. Required for everything but COUNT.",
    )
    filters: FilterExpression | None = PydanticField(default=None)

    def named_fields(self) -> set[str]:
        grouped = {name for name in (self.group_by, self.aggregated_field) if name}
        return super().named_fields() | _filter_fields(self.filters) | grouped

    @property
    def aggregation(self) -> AggregationType:
        """`function` as an enum. See `NeighborQuery.edge_direction`."""
        return AggregationType(self.function)

    def _validate_specific(self, caps: QueryCaps) -> None:
        if self.function != AggregationType.COUNT and not self.aggregated_field:
            raise ValueError(
                f"aggregated_field is required for {self.function}; only COUNT "
                "can aggregate without naming a property"
            )
        if self.group_by and self.function != AggregationType.COUNT:
            raise ValueError(
                f"group_by is only supported for COUNT, not {self.function}"
            )

Attributes

aggregated_field = PydanticField(default=None, description='Property to aggregate. Required for everything but COUNT.') class-attribute instance-attribute
aggregation property

function as an enum. See NeighborQuery.edge_direction.

filters = PydanticField(default=None) class-attribute instance-attribute
function = PydanticField(default=AggregationType.COUNT, description='Aggregation to apply.') class-attribute instance-attribute
group_by = PydanticField(default=None, description='Property to group by. COUNT only.') class-attribute instance-attribute
vertex_type = PydanticField(...) class-attribute instance-attribute

Methods:

named_fields()
Source code in graflo/architecture/query/models.py 
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def named_fields(self) -> set[str]:
    grouped = {name for name in (self.group_by, self.aggregated_field) if name}
    return super().named_fields() | _filter_fields(self.filters) | grouped

GraphQuery

Bases: ConfigBaseModel

Shared envelope for every read request.

Note

There is intentionally no caps field. Caps come from :data:HARD_CAPS and are lowered only through :meth:narrowed, so a request body cannot raise its own ceiling.

Source code in graflo/architecture/query/models.py 
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class GraphQuery(ConfigBaseModel):
    """Shared envelope for every read request.

    Note:
        There is intentionally no ``caps`` field. Caps come from
        :data:`HARD_CAPS` and are lowered only through :meth:`narrowed`, so a
        request body cannot raise its own ceiling.
    """

    limit: int = PydanticField(
        default=100, ge=1, description="Rows to return, within `max_rows`."
    )
    timeout_s: float = PydanticField(
        default=10.0, gt=0, description="Seconds to allow, within `timeout_s`."
    )
    projection: list[str] | None = PydanticField(
        default=None,
        description=(
            "Property names to return. None returns whatever the backend "
            "stores, subject to the cap's allow-list."
        ),
    )

    def finish_init(self, caps: QueryCaps | None = None) -> Self:
        """Validate against *caps*, defaulting to the core ceiling.

        Returns:
            Self, so the call composes: ``NodeQuery(...).finish_init()``.

        Raises:
            CapExceededError: Naming the cap that was exceeded.
        """
        effective = caps or HARD_CAPS
        if self.limit > effective.max_rows:
            raise CapExceededError("max_rows", self.limit, effective.max_rows)
        if self.timeout_s > effective.timeout_s:
            raise CapExceededError("timeout_s", self.timeout_s, effective.timeout_s)
        if self.projection is not None and effective.projection_allow_list is not None:
            permitted = set(effective.projection_allow_list)
            denied = sorted(n for n in self.projection if n not in permitted)
            if denied:
                raise CapExceededError(
                    "projection_allow_list", denied, effective.projection_allow_list
                )
        self._validate_specific(effective)
        return self

    def _validate_specific(self, caps: QueryCaps) -> None:
        """Per-query-kind checks. Overridden by subclasses."""

    def named_fields(self) -> set[str]:
        """Every property the query names: projection, filters, grouping."""
        return set(self.projection or ())

    def refuse_reserved(self, reserved: Collection[str]) -> None:
        """Refuse a query that names any of *reserved*.

        Raises:
            ReservedFieldError: Naming none of them.
        """
        if self.named_fields() & set(reserved):
            raise ReservedFieldError()

    def narrowed(self, caps: QueryCaps) -> Self:
        """Return a copy fitted to *caps*, raising on anything explicitly asked for.

        The split is what makes caps both enforceable and usable:

        - A value the caller **explicitly set** above a cap raises
          :class:`CapExceededError`. Silently clamping it would hand back a
          partial answer the caller believes is complete — the failure mode this
          codebase already rejected for TigerGraph edge direction.
        - A value the caller **left at its default** is clamped. A policy of
          ``max_rows=5`` must not 422 every request that simply did not mention
          a limit; that would make strict policies unusable rather than safe.

        ``model_fields_set`` is what distinguishes the two, which is precisely
        why it must be consulted rather than comparing against the default.

        Projection is always intersected rather than raising, since an
        allow-list exists to *hide* properties: refusing the request would tell
        the caller which forbidden property they guessed correctly.
        """
        effective = HARD_CAPS.narrow(caps)
        explicit = self.model_fields_set
        narrowed = self.model_copy(deep=True)

        if "limit" in explicit and self.limit > effective.max_rows:
            raise CapExceededError("max_rows", self.limit, effective.max_rows)
        narrowed.limit = min(self.limit, effective.max_rows)

        if "timeout_s" in explicit and self.timeout_s > effective.timeout_s:
            raise CapExceededError("timeout_s", self.timeout_s, effective.timeout_s)
        narrowed.timeout_s = min(self.timeout_s, effective.timeout_s)

        if effective.projection_allow_list is not None:
            # A caller who names no projection gets the allow-list, not every
            # stored property.
            permitted = set(effective.projection_allow_list)
            if narrowed.projection is None:
                narrowed.projection = list(effective.projection_allow_list)
            else:
                narrowed.projection = [n for n in narrowed.projection if n in permitted]

        narrowed._narrow_specific(effective, explicit)
        return narrowed

    def _narrow_specific(self, caps: QueryCaps, explicit: set[str]) -> None:
        """Per-query-kind fitting. Overridden by subclasses.

        Args:
            caps: The effective ceiling.
            explicit: Field names the caller actually set, so an explicit
                over-ask can raise while a default is clamped.
        """

Attributes

limit = PydanticField(default=100, ge=1, description='Rows to return, within `max_rows`.') class-attribute instance-attribute
projection = PydanticField(default=None, description="Property names to return. None returns whatever the backend stores, subject to the cap's allow-list.") class-attribute instance-attribute
timeout_s = PydanticField(default=10.0, gt=0, description='Seconds to allow, within `timeout_s`.') class-attribute instance-attribute

Methods:

finish_init(caps=None)

Validate against caps, defaulting to the core ceiling.

Returns:

Type Description
Self

Self, so the call composes: NodeQuery(...).finish_init().

Raises:

Type Description
CapExceededError

Naming the cap that was exceeded.
Source code in graflo/architecture/query/models.py 
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def finish_init(self, caps: QueryCaps | None = None) -> Self:
    """Validate against *caps*, defaulting to the core ceiling.

    Returns:
        Self, so the call composes: ``NodeQuery(...).finish_init()``.

    Raises:
        CapExceededError: Naming the cap that was exceeded.
    """
    effective = caps or HARD_CAPS
    if self.limit > effective.max_rows:
        raise CapExceededError("max_rows", self.limit, effective.max_rows)
    if self.timeout_s > effective.timeout_s:
        raise CapExceededError("timeout_s", self.timeout_s, effective.timeout_s)
    if self.projection is not None and effective.projection_allow_list is not None:
        permitted = set(effective.projection_allow_list)
        denied = sorted(n for n in self.projection if n not in permitted)
        if denied:
            raise CapExceededError(
                "projection_allow_list", denied, effective.projection_allow_list
            )
    self._validate_specific(effective)
    return self
named_fields()

Every property the query names: projection, filters, grouping.

Source code in graflo/architecture/query/models.py 
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def named_fields(self) -> set[str]:
    """Every property the query names: projection, filters, grouping."""
    return set(self.projection or ())
narrowed(caps)

Return a copy fitted to caps, raising on anything explicitly asked for.

The split is what makes caps both enforceable and usable:

  • A value the caller explicitly set above a cap raises :class:CapExceededError. Silently clamping it would hand back a partial answer the caller believes is complete — the failure mode this codebase already rejected for TigerGraph edge direction.
  • A value the caller left at its default is clamped. A policy of max_rows=5 must not 422 every request that simply did not mention a limit; that would make strict policies unusable rather than safe.

model_fields_set is what distinguishes the two, which is precisely why it must be consulted rather than comparing against the default.

Projection is always intersected rather than raising, since an allow-list exists to hide properties: refusing the request would tell the caller which forbidden property they guessed correctly.

Source code in graflo/architecture/query/models.py 
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def narrowed(self, caps: QueryCaps) -> Self:
    """Return a copy fitted to *caps*, raising on anything explicitly asked for.

    The split is what makes caps both enforceable and usable:

    - A value the caller **explicitly set** above a cap raises
      :class:`CapExceededError`. Silently clamping it would hand back a
      partial answer the caller believes is complete — the failure mode this
      codebase already rejected for TigerGraph edge direction.
    - A value the caller **left at its default** is clamped. A policy of
      ``max_rows=5`` must not 422 every request that simply did not mention
      a limit; that would make strict policies unusable rather than safe.

    ``model_fields_set`` is what distinguishes the two, which is precisely
    why it must be consulted rather than comparing against the default.

    Projection is always intersected rather than raising, since an
    allow-list exists to *hide* properties: refusing the request would tell
    the caller which forbidden property they guessed correctly.
    """
    effective = HARD_CAPS.narrow(caps)
    explicit = self.model_fields_set
    narrowed = self.model_copy(deep=True)

    if "limit" in explicit and self.limit > effective.max_rows:
        raise CapExceededError("max_rows", self.limit, effective.max_rows)
    narrowed.limit = min(self.limit, effective.max_rows)

    if "timeout_s" in explicit and self.timeout_s > effective.timeout_s:
        raise CapExceededError("timeout_s", self.timeout_s, effective.timeout_s)
    narrowed.timeout_s = min(self.timeout_s, effective.timeout_s)

    if effective.projection_allow_list is not None:
        # A caller who names no projection gets the allow-list, not every
        # stored property.
        permitted = set(effective.projection_allow_list)
        if narrowed.projection is None:
            narrowed.projection = list(effective.projection_allow_list)
        else:
            narrowed.projection = [n for n in narrowed.projection if n in permitted]

    narrowed._narrow_specific(effective, explicit)
    return narrowed
refuse_reserved(reserved)

Refuse a query that names any of reserved.

Raises:

Type Description
ReservedFieldError

Naming none of them.
Source code in graflo/architecture/query/models.py 
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def refuse_reserved(self, reserved: Collection[str]) -> None:
    """Refuse a query that names any of *reserved*.

    Raises:
        ReservedFieldError: Naming none of them.
    """
    if self.named_fields() & set(reserved):
        raise ReservedFieldError()

NeighborQuery

Bases: GraphQuery

What is adjacent to one anchor vertex.

The instance-plane counterpart of SchemaGraph.schema_neighbors. They are different questions and must never share a name: this one asks which rows are adjacent, the other which types can be.

Source code in graflo/architecture/query/models.py 
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class NeighborQuery(GraphQuery):
    """What is adjacent to one anchor vertex.

    The instance-plane counterpart of ``SchemaGraph.schema_neighbors``. They are
    different questions and must never share a name: this one asks which *rows*
    are adjacent, the other which *types* can be.
    """

    vertex_type: str = PydanticField(..., description="Logical type of the anchor.")
    key: str | dict[str, Any] = PydanticField(
        ...,
        description=(
            "A complete key of the anchor: the value of a one-field primary "
            "identity, or a mapping naming exactly the primary identity, a "
            "derived key's source fields, or one secondary identity. Any other "
            "mapping is refused: matching other fields is a lookup."
        ),
    )
    hops: int = PydanticField(
        default=1, ge=1, description="Hop distance, within `max_hops`."
    )
    direction: EdgeDirection = PydanticField(
        default=EdgeDirection.OUT,
        description=(
            "Orientation followed from the anchor. Defaults to OUT, matching "
            "`Connection.fetch_edges`; an edge declared `directed: false` is "
            "followed both ways regardless."
        ),
    )
    edge_relations: list[str] | None = PydanticField(
        default=None, description="Restrict to these relations. None means all."
    )
    filters: FilterExpression | None = PydanticField(default=None)

    def named_fields(self) -> set[str]:
        return super().named_fields() | _filter_fields(self.filters)

    @property
    def edge_direction(self) -> EdgeDirection:
        """`direction` as an enum, for handing to a driver.

        `ConfigBaseModel` sets ``use_enum_values=True``, so the stored value is
        the bare string. Backends compare against `EdgeDirection` members, and a
        string silently matches none of them — which each backend then resolves
        differently, so the same query returns different neighbourhoods
        depending on where it runs. Always cross the boundary through this.
        """
        return EdgeDirection(self.direction)

    def _validate_specific(self, caps: QueryCaps) -> None:
        if self.hops > caps.max_hops:
            raise CapExceededError("max_hops", self.hops, caps.max_hops)
        if self.edge_relations and len(self.edge_relations) > caps.max_edge_types:
            raise CapExceededError(
                "max_edge_types", len(self.edge_relations), caps.max_edge_types
            )

    def _narrow_specific(self, caps: QueryCaps, explicit: set[str]) -> None:
        if "hops" in explicit and self.hops > caps.max_hops:
            raise CapExceededError("max_hops", self.hops, caps.max_hops)
        self.hops = min(self.hops, caps.max_hops)
        if self.edge_relations and len(self.edge_relations) > caps.max_edge_types:
            raise CapExceededError(
                "max_edge_types", len(self.edge_relations), caps.max_edge_types
            )

Attributes

direction = PydanticField(default=EdgeDirection.OUT, description='Orientation followed from the anchor. Defaults to OUT, matching `Connection.fetch_edges`; an edge declared `directed: false` is followed both ways regardless.') class-attribute instance-attribute
edge_direction property

direction as an enum, for handing to a driver.

ConfigBaseModel sets use_enum_values=True, so the stored value is the bare string. Backends compare against EdgeDirection members, and a string silently matches none of them — which each backend then resolves differently, so the same query returns different neighbourhoods depending on where it runs. Always cross the boundary through this.

edge_relations = PydanticField(default=None, description='Restrict to these relations. None means all.') class-attribute instance-attribute
filters = PydanticField(default=None) class-attribute instance-attribute
hops = PydanticField(default=1, ge=1, description='Hop distance, within `max_hops`.') class-attribute instance-attribute
key = PydanticField(..., description="A complete key of the anchor: the value of a one-field primary identity, or a mapping naming exactly the primary identity, a derived key's source fields, or one secondary identity. Any other mapping is refused: matching other fields is a lookup.") class-attribute instance-attribute
vertex_type = PydanticField(..., description='Logical type of the anchor.') class-attribute instance-attribute

Methods:

named_fields()
Source code in graflo/architecture/query/models.py 
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def named_fields(self) -> set[str]:
    return super().named_fields() | _filter_fields(self.filters)

NodeQuery

Bases: GraphQuery

List vertices of one type, optionally filtered.

Source code in graflo/architecture/query/models.py 
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class NodeQuery(GraphQuery):
    """List vertices of one type, optionally filtered."""

    vertex_type: str = PydanticField(..., description="Logical vertex type name.")
    filters: FilterExpression | None = PydanticField(
        default=None, description="Predicate applied before limiting."
    )

    def named_fields(self) -> set[str]:
        return super().named_fields() | _filter_fields(self.filters)

Attributes

filters = PydanticField(default=None, description='Predicate applied before limiting.') class-attribute instance-attribute
vertex_type = PydanticField(..., description='Logical vertex type name.') class-attribute instance-attribute

Methods:

named_fields()
Source code in graflo/architecture/query/models.py 
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def named_fields(self) -> set[str]:
    return super().named_fields() | _filter_fields(self.filters)

ReservedFieldError

Bases: Refusal

A query names a field only the writer may set.

The message names no field, so a refusal tells a caller nothing about which reserved field exists.

Source code in graflo/architecture/query/models.py 
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class ReservedFieldError(Refusal):
    """A query names a field only the writer may set.

    The message names no field, so a refusal tells a caller nothing about which
    reserved field exists.
    """

    def __init__(self) -> None:
        super().__init__(
            "the query names a property that cannot be read",
            check="reserved-field",
        )

Methods:

__init__()
Source code in graflo/architecture/query/models.py 
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def __init__(self) -> None:
    super().__init__(
        "the query names a property that cannot be read",
        check="reserved-field",
    )

TraverseQuery

Bases: GraphQuery

What is reachable from a set of anchors.

Source code in graflo/architecture/query/models.py 
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class TraverseQuery(GraphQuery):
    """What is reachable from a set of anchors."""

    seeds: list[dict[str, Any]] = PydanticField(
        ...,
        min_length=1,
        description=(
            "Anchors, each `{vertex_type, key}`, `key` a complete key as for "
            "`NeighborQuery.key`. Bounded by `max_seeds`: a "
            "traversal fans out per seed, so seed count multiplies cost."
        ),
    )
    max_hops: int = PydanticField(default=2, ge=1)
    direction: EdgeDirection = PydanticField(default=EdgeDirection.ANY)
    edge_relations: list[str] | None = PydanticField(default=None)
    filters: FilterExpression | None = PydanticField(default=None)

    def named_fields(self) -> set[str]:
        return super().named_fields() | _filter_fields(self.filters)

    @property
    def edge_direction(self) -> EdgeDirection:
        """`direction` as an enum. See `NeighborQuery.edge_direction`."""
        return EdgeDirection(self.direction)

    def _validate_specific(self, caps: QueryCaps) -> None:
        if self.max_hops > caps.max_hops:
            raise CapExceededError("max_hops", self.max_hops, caps.max_hops)
        if len(self.seeds) > caps.max_seeds:
            raise CapExceededError("max_seeds", len(self.seeds), caps.max_seeds)
        if self.edge_relations and len(self.edge_relations) > caps.max_edge_types:
            raise CapExceededError(
                "max_edge_types", len(self.edge_relations), caps.max_edge_types
            )
        for seed in self.seeds:
            missing = {"vertex_type", "key"} - set(seed)
            if missing:
                raise ValueError(
                    f"seed {seed!r} is missing {sorted(missing)}; each seed needs "
                    "a vertex_type and a key"
                )

    def _narrow_specific(self, caps: QueryCaps, explicit: set[str]) -> None:
        if "max_hops" in explicit and self.max_hops > caps.max_hops:
            raise CapExceededError("max_hops", self.max_hops, caps.max_hops)
        self.max_hops = min(self.max_hops, caps.max_hops)
        # Seeds are always explicit — there is no default set of anchors — so
        # dropping any of them would silently answer a different question.
        if len(self.seeds) > caps.max_seeds:
            raise CapExceededError("max_seeds", len(self.seeds), caps.max_seeds)
        if self.edge_relations and len(self.edge_relations) > caps.max_edge_types:
            raise CapExceededError(
                "max_edge_types", len(self.edge_relations), caps.max_edge_types
            )

Attributes

direction = PydanticField(default=EdgeDirection.ANY) class-attribute instance-attribute
edge_direction property

direction as an enum. See NeighborQuery.edge_direction.

edge_relations = PydanticField(default=None) class-attribute instance-attribute
filters = PydanticField(default=None) class-attribute instance-attribute
max_hops = PydanticField(default=2, ge=1) class-attribute instance-attribute
seeds = PydanticField(..., min_length=1, description='Anchors, each `{vertex_type, key}`, `key` a complete key as for `NeighborQuery.key`. Bounded by `max_seeds`: a traversal fans out per seed, so seed count multiplies cost.') class-attribute instance-attribute

Methods:

named_fields()
Source code in graflo/architecture/query/models.py 
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def named_fields(self) -> set[str]:
    return super().named_fields() | _filter_fields(self.filters)