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版本：2.0.x

新类型

你可以定义 New Type（T）并将其用作模型字段。需要实现以下特征。

  1. 为 sea_query::Value 实现 From<T>
  2. 为 T 实现 sea_orm::TryGetable
  3. 为 T 实现 sea_query::ValueType
  4. 为 T 实现 sea_query::Nullable

包装标量类型​

你可以创建包装 SeaORM 支持的任何类型的新类型。

use sea_orm::entity::prelude::*;

#[sea_orm::model]
#[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
#[sea_orm(table_name = "custom_value_type")]
pub struct Model {
    #[sea_orm(primary_key)]
    pub id: i32,
    pub number: Integer,
}

impl ActiveModelBehavior for ActiveModel {}

#[derive(Clone, Debug, PartialEq, Eq, DeriveValueType)]
pub struct Integer(i32);
Integer 展开后的内容：
#[automatically_derived]
impl std::convert::From<Integer> for sea_orm::Value {
    fn from(source: Integer) -> Self {
        source.0.into()
    }
}

#[automatically_derived]
impl sea_orm::TryGetable for Integer {
    fn try_get_by<I: sea_orm::ColIdx>(res: &sea_orm::QueryResult, idx: I)
        -> std::result::Result<Self, sea_orm::TryGetError> {
        <i32 as sea_orm::TryGetable>::try_get_by(res, idx).map(|v| Integer(v))
    }
}

#[automatically_derived]
impl sea_orm::sea_query::ValueType for Integer {
    fn try_from(v: sea_orm::Value) -> std::result::Result<Self, sea_orm::sea_query::ValueTypeErr> {
        <i32 as sea_orm::sea_query::ValueType>::try_from(v).map(|v| Integer(v))
    }

    fn type_name() -> std::string::String {
        stringify!(Integer).to_owned()
    }

    fn array_type() -> sea_orm::sea_query::ArrayType {
        sea_orm::sea_query::ArrayType::Int
    }

    fn column_type() -> sea_orm::sea_query::ColumnType {
        sea_orm::sea_query::ColumnType::Integer
    }
}

#[automatically_derived]
impl sea_orm::sea_query::Nullable for Integer {
    fn null() -> sea_orm::Value {
        <i32 as sea_orm::sea_query::Nullable>::null()
    }
}

使用封装类型作为主键​

自 2.0.0 起
#[sea_orm::model]
#[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
#[sea_orm(table_name = "custom_value_type")]
pub struct Model {
    #[sea_orm(primary_key)]
    pub id: Integer,
}

impl ActiveModelBehavior for ActiveModel {}

支持 i8 / i16 / i32 / i64 / u8 / u16 / u32 / u64 封装类型。

包装 Vec<T>（仅 Postgres）​

use sea_orm::entity::prelude::*;

#[sea_orm::model]
#[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
#[sea_orm(table_name = "custom_vec_type")]
pub struct Model {
    #[sea_orm(primary_key)]
    pub id: i32,
    pub str_vec: StringVec,
}

impl ActiveModelBehavior for ActiveModel {}

#[derive(Clone, Debug, PartialEq, Eq, DeriveValueType)]
pub struct StringVec(pub Vec<String>);
StringVec 展开后的内容：
#[automatically_derived]
impl std::convert::From<StringVec> for Value {
    fn from(source: StringVec) -> Self {
        source.0.into()
    }
}

#[automatically_derived]
impl sea_orm::TryGetable for StringVec {
    fn try_get_by<I: sea_orm::ColIdx>(res: &QueryResult, idx: I) -> Result<Self, sea_orm::TryGetError> {
        <Vec<String> as sea_orm::TryGetable>::try_get_by(res, idx).map(|v| StringVec(v))
    }
}

#[automatically_derived]
impl sea_orm::sea_query::ValueType for StringVec {
    fn try_from(v: Value) -> Result<Self, sea_orm::sea_query::ValueTypeErr> {
        <Vec<String> as sea_orm::sea_query::ValueType>::try_from(v).map(|v| StringVec(v))
    }

    fn type_name() -> String {
        stringify!(StringVec).to_owned()
    }

    fn array_type() -> sea_orm::sea_query::ArrayType {
        sea_orm::sea_query::ArrayType::String
    }

    fn column_type() -> sea_orm::sea_query::ColumnType {
        sea_orm::sea_query::ColumnType::String(StringLen::None)
    }
}

#[automatically_derived]
impl sea_orm::sea_query::Nullable for Integer {
    fn null() -> sea_orm::Value {
        <Vec<String> as sea_orm::sea_query::Nullable>::null()
    }
}

包装 Vec<T>（后端通用）​

你也可以通过将对象序列化/反序列化为/从 JSON 来包装 Vec<T> 字段。这是在数据库间支持数组类型的后端通用方式。

use sea_orm::entity::prelude::*;
use serde::{Deserialize, Serialize};

#[sea_orm::model]
#[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel)]
#[sea_orm(table_name = "json_vec_type")]
pub struct Model {
    #[sea_orm(primary_key)]
    pub id: i32,
    pub json_vec: ObjectVec,
}

impl ActiveModelBehavior for ActiveModel {}

#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, FromJsonQueryResult)]
pub struct ObjectVec(pub Vec<MyObject>);

#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub struct MyObject {
    ..
}
ObjectVec 展开后的内容：
impl sea_orm::TryGetableFromJson for ObjectVec {}

impl std::convert::From<ObjectVec> for sea_orm::Value {
    fn from(source: ObjectVec) -> Self {
        sea_orm::Value::Json(serde_json::to_value(&source).ok().map(|s| std::boxed::Box::new(s)))
    }
}

impl sea_orm::sea_query::ValueType for ObjectVec {
    fn try_from(v: sea_orm::Value) -> Result<Self, sea_orm::sea_query::ValueTypeErr> {
        match v {
            sea_orm::Value::Json(Some(json)) => Ok(
                serde_json::from_value(*json).map_err(|_| sea_orm::sea_query::ValueTypeErr)?,
            ),
            _ => Err(sea_orm::sea_query::ValueTypeErr),
        }
    }

    fn type_name() -> String {
        stringify!(ObjectVec).to_owned()
    }

    fn array_type() -> sea_orm::sea_query::ArrayType {
        sea_orm::sea_query::ArrayType::Json
    }

    fn column_type() -> sea_orm::sea_query::ColumnType {
        sea_orm::sea_query::ColumnType::Json
    }
}

impl sea_orm::sea_query::Nullable for ObjectVec {
    fn null() -> sea_orm::Value {
        sea_orm::Value::Json(None)
    }
}

将任意类型视为 JSON​

除了包装 Vec<T> 之外，FromJsonQueryResult 宏还可用于实现 serde 的 Serialize 和 Deserialize 的任何类型，它们在与数据库交互时会被转换为/从 JSON。

use sea_orm::FromJsonQueryResult;
use sea_orm::entity::prelude::*;
use serde::{Deserialize, Serialize};

#[sea_orm::model]
#[derive(Clone, Debug, PartialEq, DeriveEntityModel)]
#[sea_orm(table_name = "json_struct")]
pub struct Model {
    #[sea_orm(primary_key)]
    pub id: i32,
    pub json_value: Metadata,
    pub json_value_opt: Option<Metadata>,
}

impl ActiveModelBehavior for ActiveModel {}

#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, FromJsonQueryResult)]
pub struct Metadata {
    pub id: i32,
    pub name: String,
    pub price: f32,
    pub notes: Option<String>,
}

枚举字符串​

自 1.1.8 起，DeriveValueType 也支持 enum 类型。它为由字符串数据库类型支持的客户端枚举提供了比 DeriveActiveEnum 更简单的替代方案。

#[derive(DeriveValueType)]
#[sea_orm(value_type = "String")]
pub enum Tag {
    Hard,
    Soft,
}

// `from_str` defaults to `std::str::FromStr::from_str`
impl std::str::FromStr for Tag {
    type Err = sea_orm::sea_query::ValueTypeErr;
    fn from_str(s: &str) -> Result<Self, Self::Err> { .. }
}

// `to_str` defaults to `std::string::ToString::to_string`.
impl std::fmt::Display for Tag {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { .. }
}
Tag 展开后的内容：
#[automatically_derived]
impl std::convert::From<Tag> for sea_orm::Value {
    fn from(source: Tag) -> Self {
        std::string::ToString::to_string(&source).into()
    }
}

#[automatically_derived]
impl sea_orm::TryGetable for Tag {
    fn try_get_by<I: sea_orm::ColIdx>(res: &sea_orm::QueryResult, idx: I)
        -> std::result::Result<Self, sea_orm::TryGetError> {
        let string = String::try_get_by(res, idx)?;
        std::str::FromStr::from_str(&string).map_err(|err| {
            sea_orm::TryGetError::DbErr(sea_orm::DbErr::TryIntoErr {
                from: "String",
                into: stringify!(#name),
                source: std::sync::Arc::new(err),
            })
        })
    }
}

#[automatically_derived]
impl sea_orm::sea_query::ValueType for Tag {
    fn try_from(v: sea_orm::Value) -> std::result::Result<Self, sea_orm::sea_query::ValueTypeErr> {
        let string = <String as sea_orm::sea_query::ValueType>::try_from(v)?;
        std::str::FromStr::from_str(&string).map_err(|_| sea_orm::sea_query::ValueTypeErr)
    }

    fn type_name() -> std::string::String {
        stringify!(Tag).to_owned()
    }

    fn array_type() -> sea_orm::sea_query::ArrayType {
        sea_orm::sea_query::ArrayType::String
    }

    fn column_type() -> sea_orm::sea_query::ColumnType {
        sea_orm::sea_query::ColumnType::String(sea_orm::sea_query::StringLen::None)
    }
}

#[automatically_derived]
impl sea_orm::sea_query::Nullable for Tag {
    fn null() -> sea_orm::Value {
        sea_orm::Value::String(None)
    }
}

你可以使用自定义函数覆盖 from_str 和 to_str，这在你在使用 strum::Display 和 strum::EnumString，或手动实现的方法时特别有用：

#[derive(DeriveValueType)]
#[sea_orm(value_type = "String", from_str = "Tag::from_str", to_str = "Tag::to_str")]
pub enum Tag {
    Color,
    Grey,
}

impl Tag {
    fn from_str(s: &str) -> Result<Self, ValueTypeErr> { .. }

    fn to_str(&self) -> &'static str { .. }
}

类字符串结构体​

自 2.0.0 起，DeriveValueType 也支持可以转换为字符串和从字符串转换的结构体类型。这与 Enum 字符串完全相同。

#[derive(Copy, Clone, Debug, PartialEq, Eq, DeriveValueType)]
#[sea_orm(value_type = "String", column_type = "Text")] // override column type
pub struct Tag3 {
    pub i: i64,
}

impl std::fmt::Display for Tag3 {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.i)
    }
}

impl std::str::FromStr for Tag3 {
    type Err = std::num::ParseIntError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let i: i64 = s.parse()?;
        Ok(Self { i })
    }
}
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