mysql_common

This crate is an implementation of basic MySql protocol primitives.

This crate:

• defines basic MySql constants;
• implements necessary functionality for MySql cached_sha2_password, mysql_native_password and legacy authentication plugins;
• implements helper traits for MySql protocol IO;
• implements support of named parameters for prepared statements;
• implements parsers for a subset of MySql protocol packets (including binlog packets);
• defines rust representation of MySql protocol values and rows;
• implements conversion between MySql values and rust types, between MySql rows and tuples of rust types.
• implements FromRow and FromValue derive macros

Supported rust types

Crate offers conversion from/to MySql values for following types (please see MySql documentation on supported ranges for numeric types). Following table refers to MySql protocol types (see Value struct) and not to MySql column types. Please see MySql documentation for column and protocol type correspondence:

Also crate provides from-row convertion for the following list of types (see FromRow trait):

Crate features

Derive Macros

FromValue Derive

Supported derivations:

• for enum – you should carefully read the corresponding section of MySql documentation.
• for newtypes (see New Type Idiom) – given that the wrapped type itself satisfies FromValue.

Enums

Container attributes:

• #[mysql(crate_name = "some_name")] – overrides an attempt to guess a crate that provides required traits
• #[mysql(rename_all = ...)] – rename all the variants according to the given case convention. The possible values are "lowercase", "UPPERCASE", "PascalCase", "camelCase", "snake_case", "SCREAMING_SNAKE_CASE", "kebab-case", "SCREAMING-KEBAB-CASE"
• #[mysql(is_integer)] – tells derive macro that the value is an integer rather than MySql ENUM. Macro won't warn if variants are sparse or greater than u16 and will not try to parse textual representation.
• #[mysql(is_string)] – tells derive macro that the value is a string rather than MySql ENUM. Macro won't warn if variants are sparse or greater than u16 and will not try to parse integer representation.

Example

Given ENUM('x-small', 'small', 'medium', 'large', 'x-large') on MySql side:

fn main() {

/// Note: the `crate_name` attribute should not be necessary.
#[derive(FromValue)]
#[mysql(rename_all = "kebab-case", crate_name = "mysql_common")]
#[repr(u8)]
enum Size {
    XSmall = 1,
    Small,
    Medium,
    Large,
    XLarge,
}

fn assert_from_row_works(x: Row) -> Size {
    from_row(x)
}

}

Newtypes

It is expected, that wrapper value satisfies FromValue or deserialize_with is given. Also note, that to support FromRow the wrapped value must satisfy Into<Value> or serialize_with must be given.

Container attributes:

• #[mysql(crate_name = "some_name")] – overrides an attempt to guess a crate to import types from
• #[mysql(bound = "Foo: Bar, Baz: Quux")] – use the following additional bounds
• #[mysql(deserialize_with = "some::path")] – use the following function to deserialize the wrapped value. Expected signature is fn (Value) -> Result<Wrapped, FromValueError>.
• #[mysql(serialize_with = "some::path")] – use the following function to serialize the wrapped value. Expected signature is fn (Wrapped) -> Value.

Example

/// Trivial example
#[derive(FromValue)]
struct Inch(i32);

/// Example of a {serialize|deserialize}_with.
#[derive(FromValue)]
#[mysql(deserialize_with = "neg_de", serialize_with = "neg_ser")]
struct Neg(i64);

/// Wrapped generic. Bounds are inferred.
#[derive(FromValue)]
struct Foo<T>(Option<T>);

/// Example of additional bounds.
#[derive(FromValue)]
#[mysql(bound = "'b: 'a, T: 'a, U: From<String>, V: From<u64>")]
struct Bar<'a, 'b, const N: usize, T, U, V>(ComplexTypeToWrap<'a, 'b, N, T, U, V>);

fn assert_from_row_works<'a, 'b, const N: usize, T, U, V>(x: Row) -> (Inch, Neg, Foo<u8>, Bar<'a, 'b, N, T, U, V>)
where 'b: 'a, T: 'a, U: From<String>, V: From<u64>,
{
    from_row(x)
}


// test boilerplate..


/// Dummy complex type with additional bounds on FromValue impl.
struct ComplexTypeToWrap<'a, 'b, const N: usize, T, U, V>([(&'a T, &'b U, V); N]);

struct FakeIr;

impl TryFrom<Value> for FakeIr {
    // ...
}

impl<'a, 'b: 'a, const N: usize, T: 'a, U: From<String>, V: From<u64>> From<FakeIr> for ComplexTypeToWrap<'a, 'b, N, T, U, V> {
    // ...
}

impl From<FakeIr> for Value {
    // ...
}

impl<'a, 'b: 'a, const N: usize, T: 'a, U: From<String>, V: From<u64>> FromValue for ComplexTypeToWrap<'a, 'b, N, T, U, V> {
    type Intermediate = FakeIr;
}

fn neg_de(v: Value) -> Result<i64, FromValueError> {
    match v {
        Value::Int(x) => Ok(-x),
        Value::UInt(x) => Ok(-(x as i64)),
        x => Err(FromValueError(x)),
    }
}

fn neg_ser(x: i64) -> Value {
    Value::Int(-x)
}

FromRow Derive

Also defines some constants on the struct:

• const TABLE_NAME: &str – if table_name is given
• const {}_FIELD: &str – for each struct field ({} is a SCREAMING_SNAKE_CASE representation of a struct field name (not a column name))

Supported derivations:

• for a struct with named fields – field name will be used as a column name to search for a value

Container attributes:

• #[mysql(crate_name = "some_name")] – overrides an attempt to guess a crate that provides required traits
• #[mysql(rename_all = ...)] – rename all column names according to the given case convention. The possible values are "lowercase", "UPPERCASE", "PascalCase", "camelCase", "snake_case", "SCREAMING_SNAKE_CASE", "kebab-case", "SCREAMING-KEBAB-CASE"
• #[mysql(table_name = "some_name")] – defines pub const TABLE_NAME: &str on the struct

Field attributes:

• #[mysql(rename = "some_name")] – overrides column name of a field
• #[mysql(json)] - column will be interpreted as a JSON string containing a value of a field type
• #[mysql(with = path::to::convert_fn)] – convert_fn will be used to deserialize a field value (expects a function with a signature that mimics `TryFrom<Value, Error=FromValueError>``)

Example

/// Note: the `crate_name` attribute should not be necessary.
#[derive(Debug, PartialEq, Eq, FromRow)]
#[mysql(table_name = "Foos", crate_name = "mysql_common")]
struct Foo {
    id: u64,
    #[mysql(json, rename = "def")]
    definition: Bar,
    child: Option<u64>,
}

#[derive(Debug, serde::Deserialize, PartialEq, Eq)]
enum Bar {
    Left,
    Right,
}

/// Returns the following row:
///
/// ```
/// +----+-----------+-------+
/// | id | def       | child |
/// +----+-----------+-------+
/// | 42 | '"Right"' | NULL  |
/// +----+-----------+-------+
/// ```
fn get_row() -> Row {
    // ...
}

assert_eq!(Foo::TABLE_NAME, "Foos");
assert_eq!(Foo::ID_FIELD, "id");
assert_eq!(Foo::DEFINITION_FIELD, "def");
assert_eq!(Foo::CHILD_FIELD, "child");

let foo = from_row::<Foo>(get_row());
assert_eq!(foo, Foo { id: 42, definition: Bar::Right, child: None });

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT) at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.