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@ -426,7 +426,7 @@ ul ul li {
} }
p + .odoc-spec { p + .odoc-spec {
margin-top: 36px; margin-top: 48px;
} }
.odoc-spec + p { .odoc-spec + p {
padding-top: 24px; padding-top: 24px;

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@ -33,10 +33,10 @@ list below and jump to whatever interests you!
prevention. prevention.
- [**`e-json`**](e-json#files)  —  sends and receives JSON - [**`e-json`**](e-json#files)  —  sends and receives JSON
securely. securely.
- [**`f-static`**](f-static)  —  serves static files from a - [**`f-static`**](f-static#files)  —  serves static files from
local directory. a local directory.
- [**`g-upload`**](g-upload)  —  receives file uploads. - [**`g-upload`**](g-upload#files)  —  receives file uploads.
- [**`h-sql`**](h-sql)  —  finally CRUD! - [**`h-sql`**](h-sql#files)  —  queries an SQL database.
- [**`i-graphql`**](i-graphql) - [**`i-graphql`**](i-graphql)
- [**`j-stream`**](j-stream) - [**`j-stream`**](j-stream)
- [**`k-websocket`**](k-websocket) - [**`k-websocket`**](k-websocket)

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example/b-session/README.md
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@ -65,7 +65,7 @@ There are two other session back ends, which are persistent:
[`Dream.run`](https://aantron.github.io/dream/#val-run) so that it doesn't [`Dream.run`](https://aantron.github.io/dream/#val-run) so that it doesn't
generate a random key each time. generate a random key each time.
- [`Dream.sql_sessions`](https://aantron.github.io/dream/#val-sql_sessions) - [`Dream.sql_sessions`](https://aantron.github.io/dream/#val-sql_sessions)
stores sessions in a database. You can try it after example stores sessions in a database. It's used in example
[**`h-sql`**](../h-sql#files). [**`h-sql`**](../h-sql#files).
<br> <br>

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# `h-sql`
<br>
Let's serve a list of comments with a comment form!
```ocaml
module type DB = Caqti_lwt.CONNECTION
module R = Caqti_request
module T = Caqti_type
let list_comments =
let query =
R.collect T.unit T.(tup2 int string)
"SELECT id, text FROM comment" in
fun (module Db : DB) ->
let%lwt comments_or_error = Db.collect_list query () in
Caqti_lwt.or_fail comments_or_error
let add_comment =
let query =
R.exec T.string
"INSERT INTO comment (text) VALUES ($1)" in
fun text (module Db : DB) ->
let%lwt unit_or_error = Db.exec query text in
Caqti_lwt.or_fail unit_or_error
let render comments request =
<html>
<body>
% comments |> List.iter (fun (_id, comment) ->
<p><%s comment %></p><% ); %>
<%s! Dream.Tag.form ~action:"/" request %>
<input name="text">
</form>
</body>
</html>
let () =
Dream.run
@@ Dream.logger
@@ Dream.sql_pool "sqlite3:db.sqlite"
@@ Dream.sql_sessions
@@ Dream.router [
Dream.get "/" (fun request ->
let%lwt comments = Dream.sql list_comments request in
Dream.respond (render comments request));
Dream.post "/" (fun request ->
match%lwt Dream.form request with
| `Ok ["text", text] ->
let%lwt () = Dream.sql (add_comment text) request in
let%lwt comments = Dream.sql list_comments request in
Dream.respond (render comments request)
| _ ->
Dream.empty `Bad_Request);
]
@@ Dream.not_found
```
<pre><code><b>$ dune exec --root . ./sql.exe</b></code></pre>
<br>
Try visiting [http://localhost:8080](http://localhost:8080) and leaving some
comments!
![Comments](https://raw.githubusercontent.com/aantron/dream/master/docs/asset/sql.png)
<br>
Several things are going on in this example. It...
- sets up the boilerplate for two SQL queries, `list_comments` and
`add_comment` with
[Caqti](https://paurkedal.github.io/ocaml-caqti/caqti/Caqti_connect_sig/module-type-S/module-type-CONNECTION/index.html);
- defines a template, `render`, for our app's main page;
- sets up a
[pool of SQL connections](https://aantron.github.io/dream/#val-sql_pool) to
`db.sqlite`; and
- sets up two routes, one for displaying the comment list, and one for
receiving new comments from our CSRF-safe form (example
[**`d-form`**](../d-form#files)).
We also take the opportunity to try out
[`Dream.sql_sessions`](https://aantron.github.io/dream/#val-sql_sessions), which
stores session data persistently in `db.sqlite`! See example
[**`b-session`**](../b-session#files) for an introduction to session management.
<br>
`db.sqlite` was initialized with this schema, using the `sqlite3` command:
```sql
CREATE TABLE comment (
id INTEGER PRIMARY KEY AUTOINCREMENT,
text NOT NULL);
CREATE TABLE dream_session (
key TEXT NOT NULL PRIMARY KEY,
id TEXT NOT NULL,
expires_at REAL NOT NULL,
payload TEXT NOT NULL
);
```
We also had to make an addition to our Dune file:
<pre>(executable
(name sql)
(libraries <b>caqti-driver-sqlite3</b> dream)
(preprocess (pps lwt_ppx)))
(rule
(targets sql.ml)
(deps sql.eml.ml)
(action (run dream_eml %{deps} --workspace %{workspace_root})))
</pre>
<!-- TODO Recommend a redirect for better refresh behavior. -->
<br>
SQLite is good for small-to-medium sites and examples. For a larger site,
microservices, or other needs, you can switch, for example, to PostgreSQL by...
- running PostgreSQL, typically in a [Docker
container](https://hub.docker.com/_/postgres/);
- changing the connection URI to `postgres://user:password@host:port`;
- using `caqti-driver-postgres`;
- replacing `INTEGER PRIMARY KEY AUTOINCREMENT` by `SERIAL PRIMARY KEY`.
A good program for examining the database locally is
[Beekeeper Studio](https://www.beekeeperstudio.io/). Dream might also integrate
an optional hosted database UI in the future, and you could choose to serve it
at some route.
<br>
See
- [`Caqti_connect_sig.S.CONNECTION`](https://paurkedal.github.io/ocaml-caqti/caqti/Caqti_connect_sig/module-type-S/module-type-CONNECTION/index.html)
for Caqti's statement runners. These are the fields of the module `Db` in the
example.
- [`Caqti_request`](https://paurkedal.github.io/ocaml-caqti/caqti/Caqti_request/)
sets up prepared statements.
- [`Caqti_type`](https://paurkedal.github.io/ocaml-caqti/caqti/Caqti_type/) is
used to specify the types of statement arguments and results.
<br>
<br>
**Next steps:**
- [**`i-graphql`**](../i-graphql#files) handles GraphQL queries and serves
GraphiQL.
- [**`j-stream`**](../j-stream#files) streams response bodies to clients.
<br>
[Up to the tutorial index](../#readme)

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@ -0,0 +1,9 @@
(executable
(name sql)
(libraries caqti-driver-sqlite3 dream)
(preprocess (pps lwt_ppx)))
(rule
(targets sql.ml)
(deps sql.eml.ml)
(action (run dream_eml %{deps} --workspace %{workspace_root})))

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(lang dune 2.0)

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@ -0,0 +1,53 @@
module type DB = Caqti_lwt.CONNECTION
module R = Caqti_request
module T = Caqti_type
let list_comments =
let query =
R.collect T.unit T.(tup2 int string)
"SELECT id, text FROM comment" in
fun (module Db : DB) ->
let%lwt comments_or_error = Db.collect_list query () in
Caqti_lwt.or_fail comments_or_error
let add_comment =
let query =
R.exec T.string
"INSERT INTO comment (text) VALUES ($1)" in
fun text (module Db : DB) ->
let%lwt unit_or_error = Db.exec query text in
Caqti_lwt.or_fail unit_or_error
let render comments request =
<html>
<body>
% comments |> List.iter (fun (_id, comment) ->
<p><%s comment %></p><% ); %>
<%s! Dream.Tag.form ~action:"/" request %>
<input name="text">
</form>
</body>
</html>
let () =
Dream.run
@@ Dream.logger
@@ Dream.sql_pool "sqlite3:db.sqlite"
@@ Dream.sql_sessions
@@ Dream.router [
Dream.get "/" (fun request ->
let%lwt comments = Dream.sql list_comments request in
Dream.respond (render comments request));
Dream.post "/" (fun request ->
match%lwt Dream.form request with
| `Ok ["text", text] ->
let%lwt () = Dream.sql (add_comment text) request in
let%lwt comments = Dream.sql list_comments request in
Dream.respond (render comments request)
| _ ->
Dream.empty `Bad_Request);
]
@@ Dream.not_found

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@ -706,7 +706,7 @@ val origin_referer_check : middleware
- their value must match [Host:] - their value must match [Host:]
Responds with [400 Bad Request] if the check fails. See example Responds with [400 Bad Request] if the check fails. See example
{{:https://github.com/aantron/dream/tree/master/example/e-json#files} {{:https://github.com/aantron/dream/tree/master/example/e-json#security}
[e-json]}. [e-json]}.
Implements the Implements the
@ -1408,9 +1408,12 @@ val graphiql : string -> handler
Dream provides thin convenience functions over Dream provides thin convenience functions over
{{:https://github.com/paurkedal/ocaml-caqti/#readme} Caqti}, an SQL {{:https://github.com/paurkedal/ocaml-caqti/#readme} Caqti}, an SQL
interface with several back ends. Dream installs the core interface with several back ends. See example
{{:https://opam.ocaml.org/packages/caqti/} [caqti]} package, but you should {{:https://github.com/aantron/dream/tree/master/example/h-sql#files}
also install at least one of: [h-sql]}.
Dream installs the core {{:https://opam.ocaml.org/packages/caqti/} [caqti]}
package, but you should also install at least one of:
- {{:https://opam.ocaml.org/packages/caqti-driver-sqlite3/} - {{:https://opam.ocaml.org/packages/caqti-driver-sqlite3/}
[caqti-driver-sqlite3]} [caqti-driver-sqlite3]}
@ -1435,7 +1438,9 @@ val sql_pool : ?size:int -> string -> middleware
(* TODO Work out the example. *) (* TODO Work out the example. *)
val sql : (Caqti_lwt.connection -> 'a promise) -> request -> 'a promise val sql : (Caqti_lwt.connection -> 'a promise) -> request -> 'a promise
(** Runs the callback with a connection from the SQL pool. (** Runs the callback with a connection from the SQL pool. See example
{{:https://github.com/aantron/dream/tree/master/example/h-sql#files}
[h-sql]}.
{[ {[
let () = let () =