package sihl
Install
Dune Dependency
Authors
Maintainers
Sources
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doc/sihl/Sihl/Database/index.html
Module Sihl.Database
Source
'a prepared_search_request
is a prepared SQL statement that can be used to sort, filter and paginate (= search) a collection.
val prepare_search_request :
search_query:string ->
filter_fragment:string ->
?sort_by_field:string ->
?format_filter:(string -> string) ->
'a Caqti_type.t ->
'a prepared_search_request
prepare_search_request ~search_query ~count_query ~filter_fragment ?sort_by_field type
returns a prepared SQL statement 'a prepared_search_request
by assembling the SQL query from the provided fragments.
search_query
is the SELECT ... FROM table
part of the query.
count_query
is a query that is executed by Sihl after the search in order to obtain the total number of items in the table. For example SELECT COUNT(\*\) FROM table
.
filter_fragment
is the fragment that is appended to search_query
for filtering. Usually you want ot OR
fields that are often searched for. For example WHERE table.field1 LIKE $1 OR table.field2 $1 OR table.field3 LIKE $1
.
sort_by_field
is an optional field name that is used for sorting. By default, the field "id" is used. Note that in order to prepare the requests, the sort field has to be known beforehand. If you want to dynamically set the field, you need to write your own query at runtime.
format_filter
is a function applied to the filter keyword before it is passed to the database. By default, a keyword "keyword" is formatted to "%skeyword%s". This might not be what you want performance-wise. If you need full control, pass in the identity function and format the keyword yourself.
type
is the caqti type of an item of the collection.
val run_request :
(module Caqti_lwt.CONNECTION) ->
'a prepared_search_request ->
[< `Asc | `Desc ] ->
'c option ->
'a ->
('b list * int) Lwt.t
val run_search_request :
'a prepared_search_request ->
[ `Asc | `Desc ] ->
string option ->
limit:int ->
offset:int ->
('a list * int) Lwt.t
run_search_request prepared_request sort filter ~limit ~offset
runs the prepared_request
and returns a partial result of the whole stored collection. The second element of the result tuple is the total amount of items in the whole collection.
prepared_request
is the returned prepared request by prepare_search_request
.
sort
is the sort order. The field that is sorted by was set by prepare_search_request
.
filter
is an optional keyword that is used to filter the collection. If no filter is provided, the collection is not filtered.
offset
is the number of items that the returned partial result is offset by.
limit
is the number of items of the returned partial result.
offset
and limit
can be used together to implement pagination.
raise_error err
raises a printable caqti error err
.
fetch_pool ()
returns the connection pool that was set up. If there was no connection pool set up, setting it up now.
find_opt request input
runs a caqti request
in the connection pool where input
is the input of the caqti request and returns one row or None
. Returns None
if no rows are found.
Note that the caqti request is only allowed to return one or zero rows, not many.
find request input
runs a caqti request
on the connection pool where input
is the input of the caqti request and returns one row. Raises an exception if no row was found.
Note that the caqti request is only allowed to return one or zero rows, not many.
collect request input
runs a caqti request
on the connection pool where input
is the input of the caqti request and retuns a list of rows.
Note that the caqti request is allowed to return one, zero or many rows.
exec request input
runs a caqti request
on the connection pool.
Note that the caqti request is not allowed to return any rows.
Use exec
to run mutations.
query f
runs the query f
on the connection pool and returns the result. If the query fails the Lwt.t fails as well.
query' f
runs the query f
on the connection pool and returns the result. Use query'
instead of query
as a shorthand when you have a single caqti request to execute.
transaction f
runs the query f
on the connection pool in a transaction and returns the result. If the query fails the Lwt.t fails as well and the transaction gets rolled back. If the database driver doesn't support transactions, transaction
gracefully becomes query
.
transaction' f
runs the query f
on the connection pool in a transaction and returns the result. If the query fails the Lwt.t fails as well and the transaction gets rolled back. If the database driver doesn't support transactions, transaction'
gracefully becomes query'
.
used_database ()
returns the database that is defined in DATABASE_URL
, None
if an unsupported database is used.