package caqti-eio

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Eio support for Caqti

Install 

dune-project
 Dependency

github.com Readme Changelog Edit opam file Versions (5)

Authors

  1. P
    Petter A. Urkedal <paurkedal@gmail.com>

Maintainers

  1. P
    Petter A. Urkedal <paurkedal@gmail.com>

Sources

caqti-v3.0.0.tbz
sha256=3ceea06ba0e8e8bcab0386b5817b68cb30fce457eaa25ada0182891d66f6a0b9
sha512=e01f546a45b04cafd5fa262e9228e5a1aabd5e0942059c073a4181c928450baf3d990cc59ffb1a33dff445b46a0e218224a23dca96e8d24cdd0ab793d08e4538

doc/caqti-eio/Caqti_eio/index.html

Module Caqti_eioSource

Establishing Connections for Eio without Unix

Note that the connect, with_connection, and connect_pool functions from this module only provides support for caqti-driver-pgx (i.e. the pgx URI scheme). The other database drivers are based on C bindings which require UNIX facilities provided by Caqti_eio_unix.connect, Caqti_eio_unix.with_connection, and Caqti_eio_unix.connect_pool, respectively.

The caqti-eio library should be considered unstable for now. Eio is in active development including its API, and the Caqti interface to it may benefit from further revision before the first major Eio release lands.

Sourcetype stdenv = < net : [ `Generic ] Eio.Net.ty Eio.Std.r ; clock : float Eio.Time.clock_ty Eio.Std.r ; mono_clock : Eio.Time.Mono.ty Eio.Std.r >
Sourcemodule Stream : Caqti.Stream.S with type 'a fiber := 'a
Sourcemodule Pool : sig ... end
Sourcemodule type CONNECTION = Caqti.Connection.S with type 'a fiber := 'a and type ('a, 'e) stream := ('a, 'e) Stream.t
include Caqti.Connect.S with type 'a fiber := 'a and type 'a with_switch := sw:Eio.Switch.t -> 'a and type 'a with_stdenv := stdenv:stdenv -> 'a and type ('a, 'e) stream := ('a, 'e) Stream.t and type ('a, 'e) pool := ('a, 'e) Pool.t and type connection = (module CONNECTION)
Sourcetype connection = (module CONNECTION)

Shortcut for the connection module when passed as a value.

connect uri locates and loads a driver which can handle uri, passes uri to the driver, which establish a connection and returns a first-class module implementing Caqti.Connection.S.

connect uri connects to the database at uri and returns a first class module implementing Caqti.Connection.S for the given database system. In case of preemptive threading, the connection must only be used from the thread where it was created.

The correct driver for the database system is inferred from the schema of uri; see the respective drivers for the supported schemas and related URI syntax. A driver can either be linked in to the application or, where supported, dynamically linked using the caqti-dynload package or the caqti.plugin library.

  • parameter subst

    Alternative to env when using the new experimental API.

  • parameter env

    If provided, this function will do a final expansion of environment variables which occurs in the query templates of the requests executed on the connection.

  • parameter config

    Configuration parameters related to the interaction with the database.

Sourceval with_connection : ?subst:(Caqti.Template.Dialect.t -> Caqti.Template.Query.subst) -> ?env:(Caqti.Private__driver_info.t -> string -> Caqti.Template.Query.t) -> ?config:Caqti.Connect.Config.t -> stdenv:stdenv -> Uri.t -> (connection -> ('a, [> Caqti.Error.load_or_connect ] as 'e) result) -> ('a, 'e) result

with_connection uri f calls connect on uri. If connect evaluates to Ok connection, with_connection passes the connection to f. Once f either evaluates to a result, or raises an exception, with_connection closes the database connection.

  • parameter config

    Passed to connect.

Sourceval connect_pool : ?pool_config:Caqti.Pool.Config.t -> ?post_connect:(connection -> (unit, 'connect_error) result) -> ?subst:(Caqti.Template.Dialect.t -> Caqti.Template.Query.subst) -> ?env:(Caqti.Private__driver_info.t -> string -> Caqti.Template.Query.t) -> ?config:Caqti.Connect.Config.t -> sw:Eio.Switch.t -> stdenv:stdenv -> Uri.t -> ((connection, [> Caqti.Error.connect ] as 'connect_error) Pool.t, [> Caqti.Error.load ]) result

connect_pool uri is a pool of database connections constructed by connect uri.

Do not use pooling for connections to volatile resources like sqlite3::memory: and beware of temporary tables or other objects which may not be shared across connections to the same URI.

If you use preemptive threading, note that the connection pool must only be used from the thread where it was created. Use thread local storage to create a separate pool per thread if necessary.

  • parameter post_connect

    A task to run after establishing a new connection and before the connection becomes available to the application. This function can be used to customize to the database session.

  • parameter config

    Passed to connect when creating new connections.

  • parameter subst

    Passed to connect when creating new connections.

  • parameter env

    Passed to connect when creating new connections.

Sourceval or_fail : ('a, [< Caqti.Error.t ]) result -> 'a

Eliminates the error-case by raising Caqti.Error.Exn.