Module Caqti1_query

(v1) One-shot and prepared queries.

exception Missing_query_string

The exception to raise in a callback passed to the various query functions below, to indicate that a query language is unsupported.

type oneshot_query = Caqti_driver_info.t -> string

The type of one-shot queries.

type prepared_query = private {
  1. pq_index : int;
    (*

    A relatively small integer unique to each query, made available to backends for efficient caching of language dependent data.

    *)
  2. pq_name : string;
    (*

    A name to use for the prepared query.

    *)
  3. pq_encode : Caqti_driver_info.t -> string;
    (*

    The SQL for each query language.

    *)
}

The type of prepared queries.

type query =
  1. | Oneshot of oneshot_query
    (*

    A one-shot query.

    *)
  2. | Prepared of prepared_query
    (*

    A prepared query.

    *)

The type of queries accepted by the CONNECTION API.

val oneshot_full : (Caqti_driver_info.t -> string) -> query

Create a one-shot family of query strings indexed by full query language descriptors.

val oneshot_fun : (Caqti_driver_info.dialect_tag -> string) -> query

Create a one-shot family of query strings indexed by language tags.

val oneshot_any : string -> query

Create a one-shot query string indiscriminately passed to any backend.

val oneshot_sql : string -> query

Create a one-shot query string expected to work with any SQL dialect.

val oneshot_sql_p : ?env:(Caqti_driver_info.dialect_tag -> string -> string) -> string -> query

Create a one-shot query string expected to work with any SQL dialect after conversion of parameters.

  • parameter env

    If provided, parameters in the form accepted by Buffer.add_substitute will be substituted using this environment.

val prepare_full : ?name:string -> (Caqti_driver_info.t -> string) -> query

Create a prepared statement dispatching on the full query language descriptor.

  • parameter name

    A fixed name for the query.

val prepare_fun : ?name:string -> (Caqti_driver_info.dialect_tag -> string) -> query

Create a prepared statement dispatching on the language tag.

  • parameter name

    A fixed name for the query.

val prepare_any : ?name:string -> string -> query

Create a prepared statement accepted by any backend. This only makes sense if backend are known to be restricted to a set sharing a common query string. Consider using prepare_sql or oneshot instead.

  • parameter name

    A fixed name for the query.

val prepare_sql : ?name:string -> string -> query

Create a prepared statement expected to work with any SQL dialect.

  • parameter name

    A fixed name for the query.

val prepare_sql_p : ?name:string -> ?env:(Caqti_driver_info.dialect_tag -> string -> string) -> string -> query

Create a prepared statement expected to work with any SQL dialect after conversion of parameters.

  • parameter name

    A fixed name for the query.

  • parameter env

    If provided, parameters in the form accepted by Buffer.add_substitute will be substituted using this environment.

type query_info = [
  1. | `Oneshot of string
  2. | `Prepared of string * string
]

An informative analogue of query, used for error reporting. For prepared queries, the first constructor argument is the name of the query.

val make_query_info : Caqti_driver_info.t -> query -> query_info

make_query_info backend query extracts the query string from query as seen by backend, for use in logging and error reporting.