Module Database.CDBI.ER

insertEntry :: EntityDescription a -> a -> DBAction ()   

Inserts an entry into the database.

Example call:

(insertEntry ed ent)

Parameters:

• ed : The EntityDescription that describes the entity to be saved
• ent : The entry to be inserted

Returns:

a DBAction with a void result

insertEntries :: EntityDescription a -> [a] -> DBAction ()   

Inserts several entries into the database.

Example call:

(insertEntries ed xs)

Parameters:

• ed : The EntityDescription that describes the entities to be saved
• xs : The list of entries to be inserted

Returns:

A Result without parameter if saving worked or an Error if there was a problem. If one saving operation reports an error, every following saving operation will be aborted but every saving operation up to that point will be executed. If these executed saving operations should also be discarded withTransaction or begin/commit/rollback should be used

restoreEntries :: EntityDescription a -> [a] -> DBAction ()   

Stores entries with their current keys in the database. It is an error if entries with the same key are already in the database. Thus, this operation is useful only to restore a database with saved data.

Example call:

(restoreEntries en xs)

Parameters:

• en : The EntityDescription that describes the entities to be saved
• xs : The list of entries to stored

Returns:

A Result without parameter if saving worked or an Error if there was a problem. If one saving operation reports an error, every following saving operation will be aborted but every saving operation up to that point will be executed. If these executed saving operations should also be discarded withTransaction or begin/commit/rollback should be used

getEntries :: Specifier -> EntityDescription a -> Criteria -> [Option] -> Maybe Int -> DBAction [a]   

Gets entries from the database.

Example call:

(getEntries spec en crit op limit)

Parameters:

• spec : Specifier All or Distinct
• en : The EntityDescription that describes the entity
• crit : Criteria for the query
• op : oreder-by clause
• limit : int value to limit number of entities returned

Returns:

a DBAction with a list of entries

getColumn :: [SetOp] -> [SingleColumnSelect a] -> [Option] -> Maybe Int -> DBAction [a]   

Gets a single Column from the database.

Example call:

(getColumn setops sels)

Parameters:

• setops : list of Setoperators to combine queries if more than one is given, can be empty otherwise
• sels : list of SingleColumnSelects to specify query, if there are more requests than can be combined with setoperators they will be ignored (where a is the type of the column)

getColumnTuple :: [SetOp] -> [TupleColumnSelect a b] -> [Option] -> Maybe Int -> DBAction [(a,b)]   

Gets two Columns from the database.

Example call:

(getColumnTuple setops sels)

Parameters:

• setops : list of Setoperators to combine queries if more than one is given, can be empty otherwise
• sels : list of TupleColumnSelects to specify queries, if there are more requests than can be combined with setoperators they will be ignored (where a is the type of the column)

getColumnTriple :: [SetOp] -> [TripleColumnSelect a b c] -> [Option] -> Maybe Int -> DBAction [(a,b,c)]   

Gets three Columns from the database.

Example call:

(getColumnTriple setops sels)

Parameters:

• setops : list of Setoperators to combine queries if more than one is given, can be empty otherwise
• sels : list of TripleColumnSelects to specify queries, if there are more requests than can be combined with setoperators they will be ignored (where a is the type of the column)

getColumnFourTuple :: [SetOp] -> [FourColumnSelect a b c d] -> [Option] -> Maybe Int -> DBAction [(a,b,c,d)]   

Gets four Columns from the database.

Example call:

(getColumnFourTuple setops sels)

Parameters:

• setops : list of Setoperators to combine queries if more than one is given, can be empty otherwise
• sels : list of FourColumnSelects to specify queries, if there are more requests than can be combined with setoperators they will be ignored (where a is the type of the column)

getColumnFiveTuple :: [SetOp] -> [FiveColumnSelect a b c d e] -> [Option] -> Maybe Int -> DBAction [(a,b,c,d,e)]   

Gets five Columns from the database.

Example call:

(getColumnFiveTuple setops sels)

Parameters:

• setops : list of Setoperators to combine queries if more than one is given, can be empty otherwise
• sels : list of FiveColumnSelects to specify queries, if there are more requests than can be combined with setoperators they will be ignored (where a is the type of the column)

getColumnSixTuple :: [SetOp] -> [SixColumnSelect a b c d e f] -> [Option] -> Maybe Int -> DBAction [(a,b,c,d,e,f)]   

Gets six Columns from the database.

Example call:

(getColumnSixTuple setops sels)

Parameters:

• setops : list of Setoperators to combine queries if more than one is given, can be empty otherwise
• sels : list of SixColumnSelects to specify queries, if there are more requests than can be combined with setoperators they will be ignored (where a is the type of the column)

getEntriesCombined :: Specifier -> CombinedDescription a -> [Join] -> Criteria -> [Option] -> Maybe Int -> DBAction [a]   

Gets combined entries from the database.

Example call:

(getEntriesCombined spec cd joins crit op limit)

Parameters:

• spec : Specifier Distinct or All
• cd : The CombinedDescription that describes the entity
• joins : joins to combine the entity, they will be applied in a left-associative manner
• crit : Criteria for the query
• op : order-by-clause
• limit : int value to determine number of values returned

Returns:

A DBAction with a list of entries

insertEntryCombined :: CombinedDescription a -> a -> DBAction ()   

Inserts combined entries.

Example call:

(insertEntryCombined cd ent)

Parameters:

• cd : The CombinedDescription that describes the entity
• ent : The combined Entity to be inserted

Returns:

A Result without parameter if saving worked or an Error if there was a problem

updateEntries :: EntityDescription a -> [ColVal] -> Constraint -> DBAction ()   

Updates entries depending on wether they fulfill the criteria or not

Example call:

(updateEntries en xs const)

Parameters:

• en : The EntityDescription descriping the Entities that are to be updated
• xs : A list of ColVal that descripe the columns that should be updated and which values are to be inserted into them
• const : A Constraint can be be given as input which describes which entities should be updated. Only entities fulfilling the constraint will be updated. Nothing updates every entry.

Returns:

A Result without parameter if everything went right, an Error if something went wrong

Further infos:

• partially defined

updateEntry :: EntityDescription a -> a -> DBAction ()   

Updates an entry by ID. Works for Entities that have a primary key as first value. This operation updates the entry in the database with the ID of the entry that is given as parameter with the values of the entry given as parameter.

Example call:

(updateEntry ed entry)

Parameters:

• ed : The EntityDescription describung the entity-type
• entry : The entry that will be updated

Returns:

A Result without parameter if everything went right, an Error if something went wrong

updateEntryCombined :: CombinedDescription a -> a -> DBAction ()   

Same as updateEntry but for combined Data

deleteEntries :: EntityDescription a -> Maybe Constraint -> DBAction ()   

Deletes entries depending on wether they fulfill the criteria or not

Example call:

(deleteEntries en const)

Parameters:

• en : The EntityDescription descriping the Entities that are to be updated
• const : A Constraint can be be given as input which describes which entities should be deleted. Only entities fulfilling the constraint will be deleted. Nothing deletes every entry.

Returns:

A Result without parameter if everything went right, an Error if something went wrong

getAllEntries :: EntityDescription a -> DBAction [a]   

Gets all entries of an entity stored in the database.

Example call:

(getAllEntries endescr)

Parameters:

• endescr : the EntityDescription describing the entities

Returns:

a DB result with the list of entries if everything went right, or an error if something went wrong

getCondEntries :: EntityDescription a -> (a -> Bool) -> DBAction [a]   

Gets all entries of an entity satisfying a given condition.

Example call:

(getCondEntries endescr cond)

Parameters:

• endescr : the EntityDescription describing the entities
• cond : a predicate on entities

Returns:

a DB result with the list of entries if everything went right, or an error if something went wrong

getEntryWithKey :: Show a => EntityDescription b -> Column c -> (a -> Value c) -> a -> DBAction b   

Gets an entry of an entity with a given key.

Example call:

(getEntryWithKey endescr keycolumn keyval key)

Parameters:

• endescr : the EntityDescription describing the entities
• keycolumn : the column containing the primary key
• keyval : the id-to-value function for entities
• key : the key of the entity to be fetched

Returns:

a DB result with the entry if everything went right, or an error if something went wrong

getEntriesWithColVal :: EntityDescription a -> Column b -> Value b -> DBAction [a]   

Get all entries of an entity where some column have a given value.

Example call:

(getEntriesWithColVal endescr valcolumn val)

Parameters:

• endescr : the EntityDescription describing the entities
• valcolumn : the column containing the required value
• val : the value required for fetched entities

Returns:

a DB result with the entry if everything went right, or an error if something went wrong

insertNewEntry :: EntityDescription a -> (a -> b -> a) -> (Int -> b) -> a -> DBAction a   

Inserts a new entry of an entity and returns the new entry with the new key.

Example call:

(insertNewEntry endescr setkey keycons entity)

Parameters:

• endescr : the EntityDescription describing the inserted entities
• setkey : the operation to set the key of an entry
• keycons : the constructor for entity keys
• entity : the entity to be inserted

Returns:

a DB result without a value if everything went right, or an error if something went wrong

deleteEntry :: EntityDescription a -> Column b -> (a -> Value b) -> a -> DBAction ()   

Deletes an existing entry from the database.

Example call:

(deleteEntry endescr keycolumn keyval entity)

Parameters:

• endescr : the EntityDescription describing the entities to be deleted
• keycolumn : the column containing the primary key
• keyval : the mapping from entities to their primary keys as SQL vals
• entity : the entity to be deleted

Returns:

a DB result without a value if everything went right, or an error if something went wrong

deleteEntryR :: EntityDescription a -> Column b -> Value b -> Column c -> Value c -> DBAction ()   

Deletes an existing binary relation entry from the database.

Example call:

(deleteEntryR endescr keycol1 keyval1 keycol2 keyval2)

Parameters:

• endescr : the EntityDescription describing the entities to be deleted
• keycol1 : the column containing the first key
• keyval1 : the value of the first key to be deleted
• keycol2 : the column containing the second key
• keyval2 : the value of the second key to be deleted

Returns:

a DB result without a value if everything went right, or an error if something went wrong

showDatabaseKey :: String -> (a -> Int) -> a -> String   

Shows a database key for an entity name as a string. Useful if a textual representation of a database key is necessary, e.g., as URL parameters in web pages. This textual representation should not be used to store database keys in attributes!

readDatabaseKey :: String -> (Int -> a) -> String -> Maybe a   

Transforms a string into a key for an entity name. Nothing is returned if the string does not represent a reasonable key.

saveDBTerms :: Show a => EntityDescription a -> String -> String -> IO ()   

Example call:

(saveDBTerms endescr dbname path)

Parameters:

• endescr : the EntityDescription of the entities to be saved
• dbname : name of the database (e.g. "database.db")
• path : directory where term file is written

restoreDBTerms :: Read a => EntityDescription a -> String -> String -> IO ()   

Restores entries saved in a term file by deleting all existing entries and inserting the saved entries.

Example call:

(restoreDBTerms endescr dbname path)

Parameters:

• endescr : the EntityDescription of the entities to be restored
• dbname : name of the database (e.g. "database.db")
• path : directory where term file was saved

runQueryOnDB :: String -> DBAction a -> IO a   

Executes a DB action on a database and returns the result. An error is raised if the DB action produces an error.

Example call:

(runQueryOnDB dbname dbaction)

Parameters:

• dbname : name of the database (e.g. "database.db")
• dbaction : a database action

Returns:

the result of the action

runTransactionOnDB :: String -> DBAction a -> IO (Either DBError a)   

Executes a DB action as a transcation on a database and returns the result. If the DB action produces an error, the transaction is rolled back and the error is returned, otherwise the transaction is committed.

Example call:

(runTransactionOnDB str dbaction)

Parameters:

• str : name of the database (e.g. "database.db")
• dbaction : a database action

Returns:

the result of the action

runJustTransactionOnDB :: String -> DBAction a -> IO a   

Executes a DB action as a transcation on a database and returns the result. An error is raised if the DB action produces an error so that the transaction is rolled back.

Example call:

(runJustTransactionOnDB str dbaction)

Parameters:

• str : name of the database (e.g. "database.db")
• dbaction : a database action

Returns:

the result of the action