Repodb.Multi.StringMap

repodb · API reference

Transactional composition of named database operations.

A multi is an ordered set of named operations executed inside one transaction. Each operation can read results produced by earlier operations, which makes it useful for workflows such as "insert a user, then insert an audit event with that user id".

let create_user_and_log email =
    Multi.empty
    |> Multi.insert_returning "user" ~table:User.table
         ~columns:[ "email" ]
         ~values:[ Driver.Value.text email ]
    |> Multi.insert_fn "audit" (fun results ->
         let row = Multi.get_row_raw_exn results "user" in
         let user_id = Driver.row_int64 row "id" in
         ( Audit.table,
           [ "user_id"; "event" ],
           [ Driver.Value.int64 user_id; Driver.Value.text "created" ] ))

Make(D).execute conn multi returns either all named results or a multi_error containing the failing operation name, normalized database error, and results completed before the failure. The surrounding transaction is rolled back on failure, so completed is diagnostic information, not a list of committed writes.

Use validate_multi in tests or CLIs to catch duplicate operation names before execution. Prefer descriptive names because they are the keys used to retrieve results and the names reported in errors.

type key = String.t
type !'a t
val empty : 'a t
val add : key -> 'a -> 'a t -> 'a t
val add_to_list : key -> 'a -> 'a list t -> 'a list t
val update : key -> ('a option -> 'a option) -> 'a t -> 'a t
val singleton : key -> 'a -> 'a t
val remove : key -> 'a t -> 'a t
val merge : 
  (key -> 'a option -> 'b option -> 'c option) ->
  'a t ->
  'b t ->
  'c t
val union : (key -> 'a -> 'a -> 'a option) -> 'a t -> 'a t -> 'a t
val cardinal : 'a t -> int
val bindings : 'a t -> (key * 'a) list
val min_binding : 'a t -> key * 'a
val min_binding_opt : 'a t -> (key * 'a) option
val max_binding : 'a t -> key * 'a
val max_binding_opt : 'a t -> (key * 'a) option
val choose : 'a t -> key * 'a
val choose_opt : 'a t -> (key * 'a) option
val find : key -> 'a t -> 'a
val find_opt : key -> 'a t -> 'a option
val find_first : (key -> bool) -> 'a t -> key * 'a
val find_first_opt : (key -> bool) -> 'a t -> (key * 'a) option
val find_last : (key -> bool) -> 'a t -> key * 'a
val find_last_opt : (key -> bool) -> 'a t -> (key * 'a) option
val iter : (key -> 'a -> unit) -> 'a t -> unit
val fold : (key -> 'a -> 'acc -> 'acc) -> 'a t -> 'acc -> 'acc
val map : ('a -> 'b) -> 'a t -> 'b t
val mapi : (key -> 'a -> 'b) -> 'a t -> 'b t
val filter : (key -> 'a -> bool) -> 'a t -> 'a t
val filter_map : (key -> 'a -> 'b option) -> 'a t -> 'b t
val partition : (key -> 'a -> bool) -> 'a t -> 'a t * 'a t
val split : key -> 'a t -> 'a t * 'a option * 'a t
val is_empty : 'a t -> bool
val mem : key -> 'a t -> bool
val equal : ('a -> 'a -> bool) -> 'a t -> 'a t -> bool
val compare : ('a -> 'a -> int) -> 'a t -> 'a t -> int
val for_all : (key -> 'a -> bool) -> 'a t -> bool
val exists : (key -> 'a -> bool) -> 'a t -> bool
val to_list : 'a t -> (key * 'a) list
val of_list : (key * 'a) list -> 'a t
val to_seq : 'a t -> (key * 'a) Seq.t
val to_rev_seq : 'a t -> (key * 'a) Seq.t
val to_seq_from : key -> 'a t -> (key * 'a) Seq.t
val add_seq : (key * 'a) Seq.t -> 'a t -> 'a t
val of_seq : (key * 'a) Seq.t -> 'a t