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package v1
import (
"context"
"fmt"
v1 "github.com/authzed/authzed-go/proto/authzed/api/v1"
"github.com/authzed/spicedb/pkg/datastore"
"github.com/authzed/spicedb/pkg/datastore/options"
"github.com/authzed/spicedb/pkg/datastore/queryshape"
)
var limitOne uint64 = 1
// checkPreconditions checks whether the preconditions are met in the context of a datastore
// read-write transaction, and returns an error if they are not met.
func checkPreconditions(
ctx context.Context,
rwt datastore.ReadWriteTransaction,
preconditions []*v1.Precondition,
) error {
for _, precond := range preconditions {
dsFilter, err := datastore.RelationshipsFilterFromPublicFilter(precond.Filter)
if err != nil {
return fmt.Errorf("error converting filter: %w", err)
}
iter, err := rwt.QueryRelationships(ctx, dsFilter, options.WithLimit(&limitOne), options.WithQueryShape(queryshape.Varying))
if err != nil {
return fmt.Errorf("error reading relationships: %w", err)
}
_, ok, err := datastore.FirstRelationshipIn(iter)
if err != nil {
return fmt.Errorf("error reading relationships from iterator: %w", err)
}
switch precond.Operation {
case v1.Precondition_OPERATION_MUST_NOT_MATCH:
if ok {
return NewPreconditionFailedErr(precond)
}
case v1.Precondition_OPERATION_MUST_MATCH:
if !ok {
return NewPreconditionFailedErr(precond)
}
default:
return fmt.Errorf("unspecified precondition operation: %s", precond.Operation)
}
}
return nil
}
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