The constraint MonadSqlTx db m indicates that m is a monadic context that can run db actions, usually as a SQL transaction. Typically, this means that db needs a connection and m can provide one, e.g. from a connection pool.

A SqlBackend represents a handle or connection to a database. It contains functions and values that allow databases to have more optimized implementations, as well as references that benefit performance and sharing.

Instead of using the SqlBackend constructor directly, use the mkSqlBackend function.

A SqlBackend is *not* thread-safe. You should not assume that a SqlBackend can be shared among threads and run concurrent queries. This *will* result in problems. Instead, you should create a Pool SqlBackend, known as a ConnectionPool, and pass that around in multi-threaded applications.

To run actions in the persistent library, you should use the runSqlConn function. If you're using a multithreaded application, use the runSqlPool function.

A monadic context in which a SQL backend is available for running database queries

Generalize from SqlPersistT to MonadSqlBackend

Get a record by identifier, if available

Get a record by unique key, if available, returning both the identifier and the record

Get a record by identifier, if available

Get a record by identifier, if available, for a non-null (not Maybe) foreign key

Unsafe unless your database is enforcing that the foreign key is valid.

Get a record by identifier, if available, for a non-null (not Maybe) foreign key

Unsafe unless your database is enforcing that the foreign key is valid.

Get many records by their respective identifiers, if available

Execute an Esqueleto SELECT query

Execute an Esqueleto SELECT query, getting only the first row

Get just the first record for the criteria

Get the Keys of all records matching the given criteria

The total number of records fulfilling the given criteria

Check if there is at least one record fulfilling the given criteria

Check if a record with this unique key exists

Insert a PersistField for every selected value

Insert a PersistField for every selected value, returning the count

Create a new record in the database

Create a new record in the database

Insert a value, checking for conflicts with any unique constraints

Create a new record in the database, returning an auto-increment ID and the inserted record

Create multiple records in the database, with specified keys

Create a new record in the database using the given key

Create multiple records in the database and return their Keys

Create multiple records in the database

Create a new record in the database

Create a new record in the database

Create a new record in the database

Create a new record in the database

Execute an Esqueleto UPDATE query

Execute an Esqueleto UPDATE query, returning the count

Update individual fields on a specific record

Update individual fields on a specific record, and retrieve the updated value from the database

This function will throw an exception if the given key is not found in the database.

Update individual fields on a specific record, and retrieve the updated Entity from the database

This function will throw an exception if the given key is not found in the database.

Update individual fields on any record matching the given criteria

Update individual fields on any record matching the given criteria

Replace the record in the database with the given key

The result is undefined if such record does not exist.

Attempt to replace the record of the given key with the given new record

First query the unique fields to make sure the replacement maintains uniqueness constraints.

Put the record in the database with the given key

If a record with the given key does not exist then a new record will be inserted.

Put many entities into the database

For each item, if a record with the given key does not exist then a new record will be inserted.

Update based on a uniqueness constraint or insert:

• Unsert the new record if it does not exist;
• If the record exists (matched via it's uniqueness constraint), then update the existing record with the parameters which is passed on as list to the function.

Update based on a given uniqueness constraint or insert:

• Insert the new record if it does not exist;
• Update the existing record that matches the given uniqueness constraint.

Put many records into the database

• Insert new records that do not exist (or violate any unique constraints);
• Replace existing records (matching any unique constraint).

Check whether there are any conflicts for unique keys with this entity and existing entities in the database

Check whether there are any conflicts for unique keys with this entity and existing entities in the database

This is useful for updating because it ignores conflicts when the particular entity already exists.

Return the single unique key for a record

Execute an Esqueleto DELETE query

Delete a specific record by identifier

Does nothing if record does not exist.

Delete a specific record by unique key

Does nothing if no record matches.

Delete all records matching the given criteria

Execute an Esqueleto DELETE query

Delete all records matching the given criteria

Commit the current transaction and begin a new one

Commit the current transaction and begin a new one

Roll back the current transaction and begin a new one

Roll back the current transaction and begin a new one

Execute a raw SQL statement

Execute a raw SQL statement

Get the SQL string for the field that an EntityField represents

Get the SQL string for the table that a PersistEntity represents

Renders a SqlQuery to Text along with the list of PersistValues that would be supplied to the database for ? placeholders

Renders a SqlQuery to Text along with the list of PersistValues that would be supplied to the database for ? placeholders

Renders a SqlQuery to Text along with the list of PersistValues that would be supplied to the database for ? placeholders

Renders a SqlQuery to Text along with the list of PersistValues that would be supplied to the database for ? placeholders

Renders a SqlQuery to Text along with the list of PersistValues that would be supplied to the database for ? placeholders