52a18c6 · project-m36 · git.iko.soy

git.iko.soy/project-m36

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fix confusing error message when creating incdep where the expressions do not have equal relation types

52a18c6AgentM9 years ago

docs/tutd_tutorial.markdown+1−1

compare with master

unifiedsplit

@@ -526,7 +526,7 @@ Foreign keys are constraints which require that certain values appearing in one

526TutorialD (master/main): foreign key s#_in_sp sp{s#} in s{s#}

527```

528

529−This expression ensure that any sp{s#} must also appear as a value in s{s#}.

529+This expression ensure that any sp{s#} must also appear as a value in s{s#}. Note that the sub-expression (on the left of "in") and the super-expression (on the right) must be of the same relation type- the generated relation values' attribute names and types must be equal. Use `rename` to make attribute names identical.

530

531#### Functional dependencies

532

src/lib/ProjectM36/Error.hs+1−1

@@ -24,7 +24,7 @@ data RelationalError = NoSuchAttributeNamesError (S.Set AttributeName)

24 | CouldNotInferAttributes

25 | RelVarNotDefinedError RelVarName

26 | RelVarAlreadyDefinedError RelVarName

27− | RelVarAssignmentTypeMismatchError Attributes Attributes --expected, found

27+ | RelationTypeMismatchError Attributes Attributes --expected, found

28 | InclusionDependencyCheckError IncDepName

29 | InclusionDependencyNameInUseError IncDepName

30 | InclusionDependencyNameNotInUseError IncDepName

src/lib/ProjectM36/RelationalExpression.hs+18−14

@@ -244,8 +244,8 @@ setRelVar relVarName rel = do

244 potentialContext = currentContext { relationVariables = newRelVars }

245

246 case checkConstraints potentialContext of

247− Just err -> pure (Left err)

247+ Left err -> pure (Left err)

248− Nothing -> do

248+ Right _ -> do

249 putStateContext potentialContext

250 return (Right ())

251

@@ -295,7 +295,7 @@ evalDatabaseContextExpr (Assign relVarName expr) = do

295 if A.attributesEqual expectedAttributes foundAttributes then

296 setRelVar relVarName rel

297 else

298− pure (Left (RelVarAssignmentTypeMismatchError expectedAttributes foundAttributes))

298+ pure (Left (RelationTypeMismatchError expectedAttributes foundAttributes))

299

300evalDatabaseContextExpr (Insert relVarName relExpr) = do

301 context <- getStateContext

@@ -359,8 +359,8 @@ evalDatabaseContextExpr (AddInclusionDependency newDepName newDep) = do

359 else do

360 let potentialContext = currContext { inclusionDependencies = newDeps }

361 case checkConstraints potentialContext of

362− Just err -> pure (Left err)

362+ Left err -> pure (Left err)

363− Nothing -> do

363+ Right _ -> do

364 putStateContext potentialContext

365 return (Right ())

366

@@ -574,22 +574,26 @@ updateTupleWithAtomExprs exprMap context tupIn = do

574 pure (updateTupleWithAtoms (M.fromList atomsAssoc) tupIn)

575

576--run verification on all constraints

577−checkConstraints :: DatabaseContext -> Maybe RelationalError

577+checkConstraints :: DatabaseContext -> Either RelationalError ()

578−checkConstraints context = case failures of

578+checkConstraints context = do

579− [] -> Nothing

579+ mapM_ (uncurry checkIncDep) (M.toList deps)

580− l:_ -> Just l

580+ pure ()

581 where

582− failures = M.elems $ M.mapMaybeWithKey checkIncDep deps

583 deps = inclusionDependencies context

582 deps = inclusionDependencies context

584− eval expr = runReader (evalRelationalExpr expr) (RelationalExprStateElems context)

583+ eval expr = evalReader (evalRelationalExpr expr)

584+ evalReader f = runReader f (RelationalExprStateElems context)

585 checkIncDep depName (InclusionDependency subsetExpr supersetExpr) = do

586+ --if both expressions are of a single-attribute (such as with a simple foreign key), the names of the attributes are irrelevant (they need not match) because the expression is unambiguous, but special-casing this to rename the attribute automatically would not be orthogonal behavior and probably cause confusion. Instead, special case the error to make it clear.

587+ typeSub <- evalReader (typeForRelationalExpr subsetExpr)

588+ typeSuper <- evalReader (typeForRelationalExpr supersetExpr)

589+ when (typeSub /= typeSuper) (Left (RelationTypeMismatchError (attributes typeSub) (attributes typeSuper)))

586 let checkExpr = Equals supersetExpr (Union subsetExpr supersetExpr)

590 let checkExpr = Equals supersetExpr (Union subsetExpr supersetExpr)

587 case eval checkExpr of

591 case eval checkExpr of

588− Left err -> Just err

592+ Left err -> Left err

589 Right resultRel -> if resultRel == relationTrue then

593 Right resultRel -> if resultRel == relationTrue then

590− Nothing

594+ pure ()

591 else

595 else

592− Just $ InclusionDependencyCheckError depName

596+ Left (InclusionDependencyCheckError depName)

593

597

594-- the type of a relational expression is equal to the relation attribute set returned from executing the relational expression; therefore, the type can be cheaply derived by evaluating a relational expression and ignoring and tuple processing

598-- the type of a relational expression is equal to the relation attribute set returned from executing the relational expression; therefore, the type can be cheaply derived by evaluating a relational expression and ignoring and tuple processing

595-- furthermore, the type of a relational expression is the resultant header of the evaluated empty-tupled relation

599-- furthermore, the type of a relational expression is the resultant header of the evaluated empty-tupled relation

src/lib/ProjectM36/TransactionGraph.hs+2−2

@@ -407,8 +407,8 @@ mergeTransactions stamp newId parentId mergeStrategy (headNameA, headNameB) grap

407 case createMergeTransaction stamp newId mergeStrategy subGraph' (transA, transB) of

408 Left err -> Left (MergeTransactionError err)

409 Right mergedTrans -> case checkConstraints (concreteDatabaseContext mergedTrans) of

410− Just err -> Left err

410+ Left err -> Left err

411− Nothing -> case headNameForTransaction disconParent graph of

411+ Right _ -> case headNameForTransaction disconParent graph of

412 Nothing -> Left (TransactionIsNotAHeadError parentId)

413 Just headName -> do

414 (newTrans, newGraph) <- addTransactionToGraph headName mergedTrans graph

test/Client/Simple.hs+1−1

@@ -55,7 +55,7 @@ testSimpleCommitFailure = TestCase $ do

55 execute $ Assign "x" (ExistingRelation relationTrue)

56 --cause error

57 execute $ Assign "x" (MakeStaticRelation failAttrs emptyTupleSet)

58− let expectedErr = Left (RelError (RelVarAssignmentTypeMismatchError V.empty failAttrs))

58+ let expectedErr = Left (RelError (RelationTypeMismatchError V.empty failAttrs))

59 assertEqual "dbc error" expectedErr err