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persistent Database.Persist.Class A convenient alias for common type signatures
type
PersistStore a = PersistStoreWrite apersistent Database.Persist.Class A backwards-compatible alias for those that don't care about distinguishing between read and write queries. It signifies the assumption that, by default, a backend can write as well as read.
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persistent Database.Persist.Class No documentation available.
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persistent Database.Persist.Class No documentation available.
type
PersistUnique a = PersistUniqueWrite apersistent Database.Persist.Class A backwards-compatible alias for those that don't care about distinguishing between read and write queries. It signifies the assumption that, by default, a backend can write as well as read.
class PersistStoreRead backend =>
PersistUniqueRead backendpersistent Database.Persist.Class Queries against Unique keys (other than the id Key). Please read the general Persistent documentation to learn how to create Unique keys. Using this with an Entity without a Unique key leads to undefined behavior. A few of these functions require a single Unique, so using an Entity with multiple Uniques is also undefined. In these cases persistent's goal is to throw an exception as soon as possible, but persistent is still transitioning to that. SQL backends automatically create uniqueness constraints, but for MongoDB you must manually place a unique index on a field to have a uniqueness constraint.
class (PersistUniqueRead backend, PersistStoreWrite backend) =>
PersistUniqueWrite backendpersistent Database.Persist.Class Some functions in this module (insertUnique, insertBy, and replaceUnique) first query the unique indexes to check for conflicts. You could instead optimistically attempt to perform the operation (e.g. replace instead of replaceUnique). However,
- there is some fragility to trying to catch the correct exception and determing the column of failure;
- an exception will automatically abort the current SQL transaction.
module Database.Persist.Class.
PersistConfig No documentation available.
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persistent Database.Persist.Class.PersistConfig Represents a value containing all the configuration options for a specific backend. This abstraction makes it easier to write code that can easily swap backends.
module Database.Persist.Class.
PersistEntity No documentation available.