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definition:
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getEntryWithKey :: Show kid => EntityDescription a -> Column k
-> (kid -> Value k) -> kid -> DBAction a
getEntryWithKey endescr keycolumn keyval key = do
vals <- getEntries All endescr
(Criteria (equal (colNum keycolumn 0) (keyval key)) Nothing)
[]
Nothing
if null vals then failDB keyNotFoundError
else return (head vals)
where
keyNotFoundError =
DBError UnknownError $
"'" ++ getTable endescr ++ "' entity with key '" ++
show key ++ "' not available"
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demand:
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no demanded arguments
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deterministic:
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deterministic operation
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documentation:
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--- Gets an entry of an entity with a given key.
--- @param endescr - the EntityDescription describing the entities
--- @param keycolumn - the column containing the primary key
--- @param keyval - the id-to-value function for entities
--- @param key - the key of the entity to be fetched
--- @return a DB result with the entry if everything went right,
--- or an error if something went wrong
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failfree:
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<FAILING>
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indeterministic:
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referentially transparent operation
|
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infix:
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no fixity defined
|
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iotype:
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{(_,_,_,_,_) |-> _}
|
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name:
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getEntryWithKey
|
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precedence:
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no precedence defined
|
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result-values:
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_
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signature:
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Prelude.Show c => Database.CDBI.Description.EntityDescription a
-> Database.CDBI.Description.Column b -> (c -> Database.CDBI.Criteria.Value b)
-> c -> Database.CDBI.Connection.DBAction a
|
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solution-complete:
|
operation might suspend on free variables
|
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terminating:
|
possibly non-terminating
|
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totally-defined:
|
possibly non-reducible on same data term
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