Merge pull request #931 from matt-duch/derive-generic
Derive Generic FromSql/ToSql
This commit is contained in:
commit
1e944c4ffc
@ -1,4 +1,4 @@
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use crate::test_type;
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use crate::{test_type, test_type_asymmetric};
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use postgres::{Client, NoTls};
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use postgres_types::{FromSql, ToSql, WrongType};
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use std::error::Error;
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@ -238,3 +238,68 @@ fn raw_ident_field() {
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test_type(&mut conn, "inventory_item", &[(item, "ROW('foo')")]);
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}
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#[test]
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fn generics() {
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#[derive(FromSql, Debug, PartialEq)]
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struct InventoryItem<T: Clone, U>
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where
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U: Clone,
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{
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name: String,
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supplier_id: T,
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price: Option<U>,
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}
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// doesn't make sense to implement derived FromSql on a type with borrows
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#[derive(ToSql, Debug, PartialEq)]
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#[postgres(name = "InventoryItem")]
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struct InventoryItemRef<'a, T: 'a + Clone, U>
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where
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U: 'a + Clone,
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{
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name: &'a str,
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supplier_id: &'a T,
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price: Option<&'a U>,
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}
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const NAME: &str = "foobar";
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const SUPPLIER_ID: i32 = 100;
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const PRICE: f64 = 15.50;
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let mut conn = Client::connect("user=postgres host=localhost port=5433", NoTls).unwrap();
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conn.batch_execute(
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"CREATE TYPE pg_temp.\"InventoryItem\" AS (
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name TEXT,
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supplier_id INT,
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price DOUBLE PRECISION
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);",
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)
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.unwrap();
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let item = InventoryItemRef {
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name: NAME,
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supplier_id: &SUPPLIER_ID,
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price: Some(&PRICE),
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};
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let item_null = InventoryItemRef {
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name: NAME,
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supplier_id: &SUPPLIER_ID,
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price: None,
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};
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test_type_asymmetric(
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&mut conn,
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"\"InventoryItem\"",
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&[
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(item, "ROW('foobar', 100, 15.50)"),
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(item_null, "ROW('foobar', 100, NULL)"),
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],
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|t: &InventoryItemRef<i32, f64>, f: &InventoryItem<i32, f64>| {
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t.name == f.name.as_str()
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&& t.supplier_id == &f.supplier_id
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&& t.price == f.price.as_ref()
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},
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);
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}
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@ -27,6 +27,30 @@ where
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}
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}
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pub fn test_type_asymmetric<T, F, S, C>(
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conn: &mut Client,
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sql_type: &str,
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checks: &[(T, S)],
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cmp: C,
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) where
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T: ToSql + Sync,
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F: FromSqlOwned,
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S: fmt::Display,
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C: Fn(&T, &F) -> bool,
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{
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for &(ref val, ref repr) in checks.iter() {
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let stmt = conn
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.prepare(&*format!("SELECT {}::{}", *repr, sql_type))
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.unwrap();
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let result: F = conn.query_one(&stmt, &[]).unwrap().get(0);
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assert!(cmp(val, &result));
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let stmt = conn.prepare(&*format!("SELECT $1::{}", sql_type)).unwrap();
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let result: F = conn.query_one(&stmt, &[val]).unwrap().get(0);
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assert!(cmp(val, &result));
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}
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}
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#[test]
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fn compile_fail() {
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trybuild::TestCases::new().compile_fail("src/compile-fail/*.rs");
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@ -1,4 +1,8 @@
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use syn::{Error, Ident, Type};
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use proc_macro2::Span;
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use syn::{
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punctuated::Punctuated, Error, GenericParam, Generics, Ident, Path, PathSegment, Type,
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TypeParamBound,
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};
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use crate::overrides::Overrides;
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@ -26,3 +30,23 @@ impl Field {
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})
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}
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}
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pub(crate) fn append_generic_bound(mut generics: Generics, bound: &TypeParamBound) -> Generics {
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for param in &mut generics.params {
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if let GenericParam::Type(param) = param {
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param.bounds.push(bound.to_owned())
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}
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}
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generics
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}
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pub(crate) fn new_derive_path(last: PathSegment) -> Path {
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let mut path = Path {
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leading_colon: None,
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segments: Punctuated::new(),
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};
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path.segments
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.push(Ident::new("postgres_types", Span::call_site()).into());
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path.segments.push(last);
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path
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}
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@ -1,10 +1,16 @@
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use proc_macro2::TokenStream;
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use proc_macro2::{Span, TokenStream};
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use quote::{format_ident, quote};
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use std::iter;
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use syn::{Data, DataStruct, DeriveInput, Error, Fields, Ident};
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use syn::{
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punctuated::Punctuated, token, AngleBracketedGenericArguments, Data, DataStruct, DeriveInput,
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Error, Fields, GenericArgument, GenericParam, Generics, Ident, Lifetime, LifetimeDef,
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PathArguments, PathSegment,
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};
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use syn::{TraitBound, TraitBoundModifier, TypeParamBound};
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use crate::accepts;
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use crate::composites::Field;
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use crate::composites::{append_generic_bound, new_derive_path};
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use crate::enums::Variant;
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use crate::overrides::Overrides;
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@ -86,10 +92,13 @@ pub fn expand_derive_fromsql(input: DeriveInput) -> Result<TokenStream, Error> {
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};
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let ident = &input.ident;
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let (generics, lifetime) = build_generics(&input.generics);
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let (impl_generics, _, _) = generics.split_for_impl();
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let (_, ty_generics, where_clause) = input.generics.split_for_impl();
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let out = quote! {
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impl<'a> postgres_types::FromSql<'a> for #ident {
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fn from_sql(_type: &postgres_types::Type, buf: &'a [u8])
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-> std::result::Result<#ident,
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impl#impl_generics postgres_types::FromSql<#lifetime> for #ident#ty_generics #where_clause {
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fn from_sql(_type: &postgres_types::Type, buf: &#lifetime [u8])
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-> std::result::Result<#ident#ty_generics,
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std::boxed::Box<dyn std::error::Error +
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std::marker::Sync +
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std::marker::Send>> {
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@ -200,3 +209,35 @@ fn composite_body(ident: &Ident, fields: &[Field]) -> TokenStream {
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})
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}
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}
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fn build_generics(source: &Generics) -> (Generics, Lifetime) {
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// don't worry about lifetime name collisions, it doesn't make sense to derive FromSql on a struct with a lifetime
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let lifetime = Lifetime::new("'a", Span::call_site());
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let mut out = append_generic_bound(source.to_owned(), &new_fromsql_bound(&lifetime));
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out.params.insert(
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0,
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GenericParam::Lifetime(LifetimeDef::new(lifetime.to_owned())),
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);
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(out, lifetime)
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}
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fn new_fromsql_bound(lifetime: &Lifetime) -> TypeParamBound {
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let mut path_segment: PathSegment = Ident::new("FromSql", Span::call_site()).into();
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let mut seg_args = Punctuated::new();
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seg_args.push(GenericArgument::Lifetime(lifetime.to_owned()));
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path_segment.arguments = PathArguments::AngleBracketed(AngleBracketedGenericArguments {
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colon2_token: None,
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lt_token: token::Lt::default(),
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args: seg_args,
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gt_token: token::Gt::default(),
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});
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TypeParamBound::Trait(TraitBound {
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lifetimes: None,
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modifier: TraitBoundModifier::None,
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paren_token: None,
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path: new_derive_path(path_segment),
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})
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}
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@ -1,10 +1,14 @@
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use proc_macro2::TokenStream;
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use proc_macro2::{Span, TokenStream};
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use quote::quote;
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use std::iter;
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use syn::{Data, DataStruct, DeriveInput, Error, Fields, Ident};
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use syn::{
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Data, DataStruct, DeriveInput, Error, Fields, Ident, TraitBound, TraitBoundModifier,
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TypeParamBound,
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};
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use crate::accepts;
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use crate::composites::Field;
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use crate::composites::{append_generic_bound, new_derive_path};
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use crate::enums::Variant;
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use crate::overrides::Overrides;
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@ -82,8 +86,10 @@ pub fn expand_derive_tosql(input: DeriveInput) -> Result<TokenStream, Error> {
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};
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let ident = &input.ident;
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let generics = append_generic_bound(input.generics.to_owned(), &new_tosql_bound());
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let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
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let out = quote! {
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impl postgres_types::ToSql for #ident {
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impl#impl_generics postgres_types::ToSql for #ident#ty_generics #where_clause {
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fn to_sql(&self,
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_type: &postgres_types::Type,
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buf: &mut postgres_types::private::BytesMut)
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@ -181,3 +187,12 @@ fn composite_body(fields: &[Field]) -> TokenStream {
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std::result::Result::Ok(postgres_types::IsNull::No)
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}
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}
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fn new_tosql_bound() -> TypeParamBound {
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TypeParamBound::Trait(TraitBound {
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lifetimes: None,
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modifier: TraitBoundModifier::None,
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paren_token: None,
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path: new_derive_path(Ident::new("ToSql", Span::call_site()).into()),
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})
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}
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