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Merge remote-tracking branch 'jgallagher/master' into rustfmt
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commit
24d5093ab8
@ -4,6 +4,10 @@
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* Adds `types::Value` for dynamic column types.
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* Adds support for user-defined aggregate functions (behind the existing `functions` Cargo feature).
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* Introduces a `RowIndex` trait allowing columns to be fetched via index (as before) or name (new).
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* Introduces `ZeroBlob` type under the `blob` module/feature exposing SQLite's zeroblob API.
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* Adds CI testing for Windows via AppVeyor.
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* Fixes a warning building libsqlite3-sys under Rust 1.6.
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* Adds an unsafe `handle()` method to `Connection`. Please file an issue if you actually use it.
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# Version 0.6.0 (2015-12-17)
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README.md
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README.md
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# Rusqlite
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[![Build Status](https://api.travis-ci.org/jgallagher/rusqlite.svg?branch=master)](https://travis-ci.org/jgallagher/rusqlite)
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[![Travis Build Status](https://api.travis-ci.org/jgallagher/rusqlite.svg?branch=master)](https://travis-ci.org/jgallagher/rusqlite)
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[![AppVeyor Build Status](https://ci.appveyor.com/api/projects/status/github/jgallagher/rusqlite?branch=master&svg=true)](https://ci.appveyor.com/project/jgallagher/rusqlite)
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Rusqlite is an ergonomic wrapper for using SQLite from Rust. It attempts to expose
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an interface similar to [rust-postgres](https://github.com/sfackler/rust-postgres). View the full
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@ -72,45 +73,6 @@ features](http://doc.crates.io/manifest.html#the-features-section). They are:
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* [`blob`](http://jgallagher.github.io/rusqlite/rusqlite/blob/index.html)
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gives `std::io::{Read, Write, Seek}` access to SQL BLOBs.
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### Design of Rows and Row
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To retrieve the result rows from a query, SQLite requires you to call
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[sqlite3_step()](https://www.sqlite.org/c3ref/step.html) on a prepared statement. You can only
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retrieve the values of the "current" row. From the Rust point of view, this means that each row
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is only valid until the next row is fetched. [rust-sqlite3](https://github.com/dckc/rust-sqlite3)
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solves this the correct way with lifetimes. However, this means that the result rows do not
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satisfy the [Iterator](http://doc.rust-lang.org/std/iter/trait.Iterator.html) trait, which means
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you cannot (as easily) loop over the rows, or use many of the helpful Iterator methods like `map`
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and `filter`.
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Instead, Rusqlite's `Rows` handle does conform to `Iterator`. It ensures safety by
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performing checks at runtime to ensure you do not try to retrieve the values of a "stale" row, and
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will panic if you do so. A specific example that will panic:
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```rust
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fn bad_function_will_panic(conn: &Connection) -> Result<i64> {
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let mut stmt = try!(conn.prepare("SELECT id FROM my_table"));
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let mut rows = try!(stmt.query(&[]));
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let row0 = try!(rows.next().unwrap());
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// row 0 is valid now...
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let row1 = try!(rows.next().unwrap());
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// row 0 is now STALE, and row 1 is valid
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let my_id = row0.get(0); // WILL PANIC because row 0 is stale
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Ok(my_id)
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}
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```
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There are other, less obvious things that may result in a panic as well, such as calling
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`collect()` on a `Rows` and then trying to use the collected rows.
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Strongly consider using the method `query_map()` instead, if you can.
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`query_map()` returns an iterator over rows-mapped-to-some-type. This
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iterator does not have any of the above issues with panics due to attempting to
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access stale rows.
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## Author
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John Gallagher, johnkgallagher@gmail.com
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src/lib.rs
23
src/lib.rs
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self.db.borrow_mut().load_extension(dylib_path.as_ref(), entry_point)
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}
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/// Get access to the underlying SQLite database connection handle.
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///
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/// # Warning
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///
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/// You should not need to use this function. If you do need to, please [open an issue
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/// on the rusqlite repository](https://github.com/jgallagher/rusqlite/issues) and describe
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/// your use case. This function is unsafe because it gives you raw access to the SQLite
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/// connection, and what you do with it could impact the safety of this `Connection`.
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pub unsafe fn handle(&self) -> *mut ffi::Struct_sqlite3 {
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self.db.borrow().db()
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}
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fn decode_result(&self, code: c_int) -> Result<()> {
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self.db.borrow_mut().decode_result(code)
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}
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@ -977,6 +989,9 @@ pub type SqliteRows<'stmt> = Rows<'stmt>;
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///
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/// ## Warning
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///
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/// Strongly consider using `query_map` or `query_and_then` instead of `query`; the former do not
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/// suffer from the following problem.
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///
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/// Due to the way SQLite returns result rows of a query, it is not safe to attempt to get values
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/// from a row after it has become stale (i.e., `next()` has been called again on the `Rows`
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/// iterator). For example:
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@ -988,7 +1003,7 @@ pub type SqliteRows<'stmt> = Rows<'stmt>;
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/// let mut rows = try!(stmt.query(&[]));
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///
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/// let row0 = try!(rows.next().unwrap());
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/// // row 0 is value now...
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/// // row 0 is valid for now...
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///
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/// let row1 = try!(rows.next().unwrap());
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/// // row 0 is now STALE, and row 1 is valid
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@ -1002,12 +1017,6 @@ pub type SqliteRows<'stmt> = Rows<'stmt>;
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/// (which would result in a collection of rows, only the last of which can safely be used) and
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/// `min`/`max` (which could return a stale row unless the last row happened to be the min or max,
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/// respectively).
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///
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/// This problem could be solved by changing the signature of `next` to tie the lifetime of the
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/// returned row to the lifetime of (a mutable reference to) the result rows handle, but this would
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/// no longer implement `Iterator`, and therefore you would lose access to the majority of
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/// functions which are useful (such as support for `for ... in ...` looping, `map`, `filter`,
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/// etc.).
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pub struct Rows<'stmt> {
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stmt: &'stmt Statement<'stmt>,
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current_row: Rc<Cell<c_int>>,
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