Netcgi

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module type DBI_DRIVER = sig

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type connection

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val connect : ?host:string -> ?port:string -> ?user:string -> ?password:string -> string -> connection

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val close : connection -> unit

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val closed : connection -> bool

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val commit : connection -> unit

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val ping : connection -> bool

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val rollback : connection -> unit

end

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module type DBI_POOL = sig

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type connection

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val get : Netcgi.cgi -> ?host:string -> ?port:string -> ?user:string -> ?password:string -> string -> connection

Example: module MyPool = DbiPool(Dbi_postgres)

let dbh = MyPool.get request "database_name"

Returns an unused Dbi.connection handle from the pool of database handles. Or it may create a new database connection and return that.

The parameters uniquely identify the database name (eg. "comments") and optional parameters. Separate pools are maintained for each combination of parameters.

The connection is automatically returned to the pool at the end of the cgi request. After this time the connection may be given away to another user. For this reason, the calling code must NEVER stash the connection across requests (instead, call get to get a new handle each time).

On returning the handle to the pool, the pool performs a ROLLBACK operation on the handle, thus losing any changes (INSERT, etc.) made to the database. If the program wants to preserve changes, it must perform a COMMIT operation itself, by calling Dbi.connection.commit.

end

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module DbiPool : functor (Dbi_driver : DBI_DRIVER) -> DBI_POOL with type connection = Dbi_driver.connection

module MyPool = DbiPool (Dbi_postgres)

creates a pool of PostgreSQL database handles. To use them:

let dbh = MyPool.get r "database_name"

Gets you a new or recycled database handle dbh which is valid until the end of the current Apache request.

module Netcgi_dbi