1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
use crate::{Result, Statement, ToSql};

mod sealed {
    /// This trait exists just to ensure that the only impls of `trait Params`
    /// that are allowed are ones in this crate.
    pub trait Sealed {}
}
use sealed::Sealed;

/// Trait used for [sets of parameter][params] passed into SQL
/// statements/queries.
///
/// [params]: https://www.sqlite.org/c3ref/bind_blob.html
///
/// Note: Currently, this trait can only be implemented inside this crate.
/// Additionally, it's methods (which are `doc(hidden)`) should currently not be
/// considered part of the stable API, although it's possible they will
/// stabilize in the future.
///
/// # Passing parameters to SQLite
///
/// Many functions in this library let you pass parameters to SQLite. Doing this
/// lets you avoid any risk of SQL injection, and is simpler than escaping
/// things manually. Aside from deprecated functions and a few helpers, this is
/// indicated by the function taking a generic argument that implements `Params`
/// (this trait).
///
/// ## Positional parameters
///
/// For cases where you want to pass a list of parameters where the number of
/// parameters is known at compile time, this can be done in one of the
/// following ways:
///
/// - For small lists of parameters up to 16 items, they may alternatively be
///   passed as a tuple, as in `thing.query((1, "foo"))`.
///
///     This is somewhat inconvenient for a single item, since you need a
///     weird-looking trailing comma: `thing.query(("example",))`. That case is
///     perhaps more cleanly expressed as `thing.query(["example"])`.
///
/// - Using the [`rusqlite::params!`](crate::params!) macro, e.g.
///   `thing.query(rusqlite::params![1, "foo", bar])`. This is mostly useful for
///   heterogeneous lists where the number of parameters greater than 16, or
///   homogenous lists of parameters where the number of parameters exceeds 32.
///
/// - For small homogeneous lists of parameters, they can either be passed as:
///
///     - an array, as in `thing.query([1i32, 2, 3, 4])` or `thing.query(["foo",
///       "bar", "baz"])`.
///
///     - a reference to an array of references, as in `thing.query(&["foo",
///       "bar", "baz"])` or `thing.query(&[&1i32, &2, &3])`.
///
///         (Note: in this case we don't implement this for slices for coherence
///         reasons, so it really is only for the "reference to array" types —
///         hence why the number of parameters must be <= 32 or you need to
///         reach for `rusqlite::params!`)
///
///     Unfortunately, in the current design it's not possible to allow this for
///     references to arrays of non-references (e.g. `&[1i32, 2, 3]`). Code like
///     this should instead either use `params!`, an array literal, a `&[&dyn
///     ToSql]` or if none of those work, [`ParamsFromIter`].
///
/// - As a slice of `ToSql` trait object references, e.g. `&[&dyn ToSql]`. This
///   is mostly useful for passing parameter lists around as arguments without
///   having every function take a generic `P: Params`.
///
/// ### Example (positional)
///
/// ```rust,no_run
/// # use rusqlite::{Connection, Result, params};
/// fn update_rows(conn: &Connection) -> Result<()> {
///     let mut stmt = conn.prepare("INSERT INTO test (a, b) VALUES (?1, ?2)")?;
///
///     // Using a tuple:
///     stmt.execute((0, "foobar"))?;
///
///     // Using `rusqlite::params!`:
///     stmt.execute(params![1i32, "blah"])?;
///
///     // array literal — non-references
///     stmt.execute([2i32, 3i32])?;
///
///     // array literal — references
///     stmt.execute(["foo", "bar"])?;
///
///     // Slice literal, references:
///     stmt.execute(&[&2i32, &3i32])?;
///
///     // Note: The types behind the references don't have to be `Sized`
///     stmt.execute(&["foo", "bar"])?;
///
///     // However, this doesn't work (see above):
///     // stmt.execute(&[1i32, 2i32])?;
///     Ok(())
/// }
/// ```
///
/// ## Named parameters
///
/// SQLite lets you name parameters using a number of conventions (":foo",
/// "@foo", "$foo"). You can pass named parameters in to SQLite using rusqlite
/// in a few ways:
///
/// - Using the [`rusqlite::named_params!`](crate::named_params!) macro, as in
///   `stmt.execute(named_params!{ ":name": "foo", ":age": 99 })`. Similar to
///   the `params` macro, this is most useful for heterogeneous lists of
///   parameters, or lists where the number of parameters exceeds 32.
///
/// - As a slice of `&[(&str, &dyn ToSql)]`. This is what essentially all of
///   these boil down to in the end, conceptually at least. In theory you can
///   pass this as `stmt`.
///
/// - As array references, similar to the positional params. This looks like
///   `thing.query(&[(":foo", &1i32), (":bar", &2i32)])` or
///   `thing.query(&[(":foo", "abc"), (":bar", "def")])`.
///
/// Note: Unbound named parameters will be left to the value they previously
/// were bound with, falling back to `NULL` for parameters which have never been
/// bound.
///
/// ### Example (named)
///
/// ```rust,no_run
/// # use rusqlite::{Connection, Result, named_params};
/// fn insert(conn: &Connection) -> Result<()> {
///     let mut stmt = conn.prepare("INSERT INTO test (key, value) VALUES (:key, :value)")?;
///     // Using `rusqlite::params!`:
///     stmt.execute(named_params! { ":key": "one", ":val": 2 })?;
///     // Alternatively:
///     stmt.execute(&[(":key", "three"), (":val", "four")])?;
///     // Or:
///     stmt.execute(&[(":key", &100), (":val", &200)])?;
///     Ok(())
/// }
/// ```
///
/// ## No parameters
///
/// You can just use an empty tuple or the empty array literal to run a query
/// that accepts no parameters.
///
/// ### Example (no parameters)
///
/// The empty tuple:
///
/// ```rust,no_run
/// # use rusqlite::{Connection, Result, params};
/// fn delete_all_users(conn: &Connection) -> Result<()> {
///     // You may also use `()`.
///     conn.execute("DELETE FROM users", ())?;
///     Ok(())
/// }
/// ```
///
/// The empty array:
///
/// ```rust,no_run
/// # use rusqlite::{Connection, Result, params};
/// fn delete_all_users(conn: &Connection) -> Result<()> {
///     // Just use an empty array (e.g. `[]`) for no params.
///     conn.execute("DELETE FROM users", [])?;
///     Ok(())
/// }
/// ```
///
/// ## Dynamic parameter list
///
/// If you have a number of parameters which is unknown at compile time (for
/// example, building a dynamic query at runtime), you have two choices:
///
/// - Use a `&[&dyn ToSql]`. This is often annoying to construct if you don't
///   already have this type on-hand.
/// - Use the [`ParamsFromIter`] type. This essentially lets you wrap an
///   iterator some `T: ToSql` with something that implements `Params`. The
///   usage of this looks like `rusqlite::params_from_iter(something)`.
///
/// A lot of the considerations here are similar either way, so you should see
/// the [`ParamsFromIter`] documentation for more info / examples.
pub trait Params: Sealed {
    // XXX not public api, might not need to expose.
    //
    // Binds the parameters to the statement. It is unlikely calling this
    // explicitly will do what you want. Please use `Statement::query` or
    // similar directly.
    //
    // For now, just hide the function in the docs...
    #[doc(hidden)]
    fn __bind_in(self, stmt: &mut Statement<'_>) -> Result<()>;
}

// Explicitly impl for empty array. Critically, for `conn.execute([])` to be
// unambiguous, this must be the *only* implementation for an empty array.
//
// This sadly prevents `impl<T: ToSql, const N: usize> Params for [T; N]`, which
// forces people to use `params![...]` or `rusqlite::params_from_iter` for long
// homogenous lists of parameters. This is not that big of a deal, but is
// unfortunate, especially because I mostly did it because I wanted a simple
// syntax for no-params that didnt require importing -- the empty tuple fits
// that nicely, but I didn't think of it until much later.
//
// Admittedly, if we did have the generic impl, then we *wouldn't* support the
// empty array literal as a parameter, since the `T` there would fail to be
// inferred. The error message here would probably be quite bad, and so on
// further thought, probably would end up causing *more* surprises, not less.
impl Sealed for [&(dyn ToSql + Send + Sync); 0] {}
impl Params for [&(dyn ToSql + Send + Sync); 0] {
    #[inline]
    fn __bind_in(self, stmt: &mut Statement<'_>) -> Result<()> {
        stmt.ensure_parameter_count(0)
    }
}

impl Sealed for &[&dyn ToSql] {}
impl Params for &[&dyn ToSql] {
    #[inline]
    fn __bind_in(self, stmt: &mut Statement<'_>) -> Result<()> {
        stmt.bind_parameters(self)
    }
}

impl Sealed for &[(&str, &dyn ToSql)] {}
impl Params for &[(&str, &dyn ToSql)] {
    #[inline]
    fn __bind_in(self, stmt: &mut Statement<'_>) -> Result<()> {
        stmt.bind_parameters_named(self)
    }
}

// Manual impls for the empty and singleton tuple, although the rest are covered
// by macros.
impl Sealed for () {}
impl Params for () {
    #[inline]
    fn __bind_in(self, stmt: &mut Statement<'_>) -> Result<()> {
        stmt.ensure_parameter_count(0)
    }
}

// I'm pretty sure you could tweak the `single_tuple_impl` to accept this.
impl<T: ToSql> Sealed for (T,) {}
impl<T: ToSql> Params for (T,) {
    #[inline]
    fn __bind_in(self, stmt: &mut Statement<'_>) -> Result<()> {
        stmt.ensure_parameter_count(1)?;
        stmt.raw_bind_parameter(1, self.0)?;
        Ok(())
    }
}

macro_rules! single_tuple_impl {
    ($count:literal : $(($field:tt $ftype:ident)),* $(,)?) => {
        impl<$($ftype,)*> Sealed for ($($ftype,)*) where $($ftype: ToSql,)* {}
        impl<$($ftype,)*> Params for ($($ftype,)*) where $($ftype: ToSql,)* {
            fn __bind_in(self, stmt: &mut Statement<'_>) -> Result<()> {
                stmt.ensure_parameter_count($count)?;
                $({
                    debug_assert!($field < $count);
                    stmt.raw_bind_parameter($field + 1, self.$field)?;
                })+
                Ok(())
            }
        }
    }
}

// We use a the macro for the rest, but don't bother with trying to implement it
// in a single invocation (it's possible to do, but my attempts were almost the
// same amount of code as just writing it out this way, and much more dense --
// it is a more complicated case than the TryFrom macro we have for row->tuple).
//
// Note that going up to 16 (rather than the 12 that the impls in the stdlib
// usually support) is just because we did the same in the `TryFrom<Row>` impl.
// I didn't catch that then, but there's no reason to remove it, and it seems
// nice to be consistent here; this way putting data in the database and getting
// data out of the database are more symmetric in a (mostly superficial) sense.
single_tuple_impl!(2: (0 A), (1 B));
single_tuple_impl!(3: (0 A), (1 B), (2 C));
single_tuple_impl!(4: (0 A), (1 B), (2 C), (3 D));
single_tuple_impl!(5: (0 A), (1 B), (2 C), (3 D), (4 E));
single_tuple_impl!(6: (0 A), (1 B), (2 C), (3 D), (4 E), (5 F));
single_tuple_impl!(7: (0 A), (1 B), (2 C), (3 D), (4 E), (5 F), (6 G));
single_tuple_impl!(8: (0 A), (1 B), (2 C), (3 D), (4 E), (5 F), (6 G), (7 H));
single_tuple_impl!(9: (0 A), (1 B), (2 C), (3 D), (4 E), (5 F), (6 G), (7 H), (8 I));
single_tuple_impl!(10: (0 A), (1 B), (2 C), (3 D), (4 E), (5 F), (6 G), (7 H), (8 I), (9 J));
single_tuple_impl!(11: (0 A), (1 B), (2 C), (3 D), (4 E), (5 F), (6 G), (7 H), (8 I), (9 J), (10 K));
single_tuple_impl!(12: (0 A), (1 B), (2 C), (3 D), (4 E), (5 F), (6 G), (7 H), (8 I), (9 J), (10 K), (11 L));
single_tuple_impl!(13: (0 A), (1 B), (2 C), (3 D), (4 E), (5 F), (6 G), (7 H), (8 I), (9 J), (10 K), (11 L), (12 M));
single_tuple_impl!(14: (0 A), (1 B), (2 C), (3 D), (4 E), (5 F), (6 G), (7 H), (8 I), (9 J), (10 K), (11 L), (12 M), (13 N));
single_tuple_impl!(15: (0 A), (1 B), (2 C), (3 D), (4 E), (5 F), (6 G), (7 H), (8 I), (9 J), (10 K), (11 L), (12 M), (13 N), (14 O));
single_tuple_impl!(16: (0 A), (1 B), (2 C), (3 D), (4 E), (5 F), (6 G), (7 H), (8 I), (9 J), (10 K), (11 L), (12 M), (13 N), (14 O), (15 P));

macro_rules! impl_for_array_ref {
    ($($N:literal)+) => {$(
        // These are already generic, and there's a shedload of them, so lets
        // avoid the compile time hit from making them all inline for now.
        impl<T: ToSql + ?Sized> Sealed for &[&T; $N] {}
        impl<T: ToSql + ?Sized> Params for &[&T; $N] {
            fn __bind_in(self, stmt: &mut Statement<'_>) -> Result<()> {
                stmt.bind_parameters(self)
            }
        }
        impl<T: ToSql + ?Sized> Sealed for &[(&str, &T); $N] {}
        impl<T: ToSql + ?Sized> Params for &[(&str, &T); $N] {
            fn __bind_in(self, stmt: &mut Statement<'_>) -> Result<()> {
                stmt.bind_parameters_named(self)
            }
        }
        impl<T: ToSql> Sealed for [T; $N] {}
        impl<T: ToSql> Params for [T; $N] {
            #[inline]
            fn __bind_in(self, stmt: &mut Statement<'_>) -> Result<()> {
                stmt.bind_parameters(&self)
            }
        }
    )+};
}

// Following libstd/libcore's (old) lead, implement this for arrays up to `[_;
// 32]`. Note `[_; 0]` is intentionally omitted for coherence reasons, see the
// note above the impl of `[&dyn ToSql; 0]` for more information.
//
// Note that this unfortunately means we can't use const generics here, but I
// don't really think it matters -- users who hit that can use `params!` anyway.
impl_for_array_ref!(
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
    18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
);

/// Adapter type which allows any iterator over [`ToSql`] values to implement
/// [`Params`].
///
/// This struct is created by the [`params_from_iter`] function.
///
/// This can be useful if you have something like an `&[String]` (of unknown
/// length), and you want to use them with an API that wants something
/// implementing `Params`. This way, you can avoid having to allocate storage
/// for something like a `&[&dyn ToSql]`.
///
/// This essentially is only ever actually needed when dynamically generating
/// SQL — static SQL (by definition) has the number of parameters known
/// statically. As dynamically generating SQL is itself pretty advanced, this
/// API is itself for advanced use cases (See "Realistic use case" in the
/// examples).
///
/// # Example
///
/// ## Basic usage
///
/// ```rust,no_run
/// use rusqlite::{params_from_iter, Connection, Result};
/// use std::collections::BTreeSet;
///
/// fn query(conn: &Connection, ids: &BTreeSet<String>) -> Result<()> {
///     assert_eq!(ids.len(), 3, "Unrealistic sample code");
///
///     let mut stmt = conn.prepare("SELECT * FROM users WHERE id IN (?1, ?2, ?3)")?;
///     let _rows = stmt.query(params_from_iter(ids.iter()))?;
///
///     // use _rows...
///     Ok(())
/// }
/// ```
///
/// ## Realistic use case
///
/// Here's how you'd use `ParamsFromIter` to call [`Statement::exists`] with a
/// dynamic number of parameters.
///
/// ```rust,no_run
/// use rusqlite::{Connection, Result};
///
/// pub fn any_active_users(conn: &Connection, usernames: &[String]) -> Result<bool> {
///     if usernames.is_empty() {
///         return Ok(false);
///     }
///
///     // Note: `repeat_vars` never returns anything attacker-controlled, so
///     // it's fine to use it in a dynamically-built SQL string.
///     let vars = repeat_vars(usernames.len());
///
///     let sql = format!(
///         // In practice this would probably be better as an `EXISTS` query.
///         "SELECT 1 FROM user WHERE is_active AND name IN ({}) LIMIT 1",
///         vars,
///     );
///     let mut stmt = conn.prepare(&sql)?;
///     stmt.exists(rusqlite::params_from_iter(usernames))
/// }
///
/// // Helper function to return a comma-separated sequence of `?`.
/// // - `repeat_vars(0) => panic!(...)`
/// // - `repeat_vars(1) => "?"`
/// // - `repeat_vars(2) => "?,?"`
/// // - `repeat_vars(3) => "?,?,?"`
/// // - ...
/// fn repeat_vars(count: usize) -> String {
///     assert_ne!(count, 0);
///     let mut s = "?,".repeat(count);
///     // Remove trailing comma
///     s.pop();
///     s
/// }
/// ```
///
/// That is fairly complex, and even so would need even more work to be fully
/// production-ready:
///
/// - production code should ensure `usernames` isn't so large that it will
///   surpass [`conn.limit(Limit::SQLITE_LIMIT_VARIABLE_NUMBER)`][limits]),
///   chunking if too large. (Note that the limits api requires rusqlite to have
///   the "limits" feature).
///
/// - `repeat_vars` can be implemented in a way that avoids needing to allocate
///   a String.
///
/// - Etc...
///
/// [limits]: crate::Connection::limit
///
/// This complexity reflects the fact that `ParamsFromIter` is mainly intended
/// for advanced use cases — most of the time you should know how many
/// parameters you have statically (and if you don't, you're either doing
/// something tricky, or should take a moment to think about the design).
#[derive(Clone, Debug)]
pub struct ParamsFromIter<I>(I);

/// Constructor function for a [`ParamsFromIter`]. See its documentation for
/// more.
#[inline]
pub fn params_from_iter<I>(iter: I) -> ParamsFromIter<I>
where
    I: IntoIterator,
    I::Item: ToSql,
{
    ParamsFromIter(iter)
}

impl<I> Sealed for ParamsFromIter<I>
where
    I: IntoIterator,
    I::Item: ToSql,
{
}

impl<I> Params for ParamsFromIter<I>
where
    I: IntoIterator,
    I::Item: ToSql,
{
    #[inline]
    fn __bind_in(self, stmt: &mut Statement<'_>) -> Result<()> {
        stmt.bind_parameters(self.0)
    }
}