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Add prefix option to nested attribute in FromQueryResult and PartialModel #2989

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4919acf
Add `prefix` option to `nested` attribute in FromQueryResult and
YouKnow-sys Mar 5, 2026
0b67194
Improve error spans for duplicate nested fields
YouKnow-sys Mar 6, 2026
8db3bbe
Don't count empty strings as prefix
YouKnow-sys Mar 6, 2026
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103 changes: 73 additions & 30 deletions sea-orm-macros/src/derives/from_query_result.rs
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Original file line number Diff line number Diff line change
@@ -1,20 +1,17 @@
use std::collections::{HashMap, hash_map::Entry};

use super::util::GetMeta;
use proc_macro2::{Ident, TokenStream};
use quote::{ToTokens, format_ident, quote, quote_spanned};
use quote::{ToTokens, quote};
use syn::{
Data, DataStruct, DeriveInput, Fields, Generics, Meta, ext::IdentExt, punctuated::Punctuated,
token::Comma,
Data, DataStruct, DeriveInput, Error, Fields, Generics, Meta, ext::IdentExt,
punctuated::Punctuated, token::Comma,
};

#[derive(Debug)]
enum Error {
InputNotStruct,
}

pub(super) enum ItemType {
Flat,
Skip,
Nested,
Nested { prefix: Option<String> },
}

pub(super) struct DeriveFromQueryResult {
Expand Down Expand Up @@ -63,13 +60,16 @@ impl ToTokens for TryFromQueryResultCheck<'_> {
let #ident = std::default::Default::default();
});
}
ItemType::Nested => {
let prefix = if self.0 {
let name = ident.unraw().to_string();
quote! { &format!("{pre}{}_", #name) }
} else {
quote! { pre }
ItemType::Nested { prefix } => {
let prefix = match (self.0, prefix) {
(_, Some(p)) => quote! { &format!("{pre}{}", #p) },
(true, None) => {
let name = ident.unraw().to_string();
quote! { &format!("{pre}{}_", #name) }
}
(false, None) => quote! { pre },
};

tokens.extend(quote! {
let #ident = match sea_orm::FromQueryResult::from_query_result_nullable(row, #prefix) {
Err(v @ sea_orm::TryGetError::DbErr(_)) => {
Expand All @@ -90,7 +90,7 @@ impl ToTokens for TryFromQueryResultAssignment<'_> {
let FromQueryResultItem { ident, typ, .. } = self.0;

match typ {
ItemType::Flat | ItemType::Nested => {
ItemType::Flat | ItemType::Nested { .. } => {
tokens.extend(quote! {
#ident: #ident?,
});
Expand Down Expand Up @@ -118,10 +118,17 @@ impl DeriveFromQueryResult {
fields: Fields::Named(named),
..
}) => named.named,
_ => return Err(Error::InputNotStruct),
_ => {
return Err(Error::new(
ident.span(),
"you can only derive `FromQueryResult` on named struct",
));
}
};

let mut fields = Vec::with_capacity(parsed_fields.len());
let mut seen_nested: HashMap<(syn::Type, Option<String>), TokenStream> = HashMap::new();

for parsed_field in parsed_fields {
let mut typ = ItemType::Flat;
let mut alias = None;
Expand All @@ -135,16 +142,59 @@ impl DeriveFromQueryResult {
if meta.exists("skip") {
typ = ItemType::Skip;
} else if meta.exists("nested") {
typ = ItemType::Nested;
} else if let Some(alias_) = meta.get_as_kv("from_alias") {
alias = Some(alias_);
typ = ItemType::Nested { prefix: None };
} else if let Some(list) = meta.get_list_args("nested") {
let mut prefix = None;

for m in list.iter() {
match m.get_as_kv("prefix") {
Some(p) => prefix = (!p.is_empty()).then_some(p),
None => {
return Err(Error::new_spanned(
m,
"invalid nested attribute, expected `prefix = \"...\"`",
));
}
}
}

typ = ItemType::Nested { prefix };
} else {
alias = meta.get_as_kv("alias");
alias = meta
.get_as_kv("from_alias")
.or_else(|| meta.get_as_kv("alias"));
}
}
}
}
let ident = format_ident!("{}", parsed_field.ident.unwrap().to_string());

let field_tokens = parsed_field.to_token_stream();
let ident = parsed_field.ident.unwrap();

if let ItemType::Nested { ref prefix } = typ {
let key = (parsed_field.ty, prefix.clone());
match seen_nested.entry(key) {
Entry::Occupied(e) => {
let msg = match prefix {
Some(p) => format!(
"multiple nested fields with the same type share prefix \"{p}\""
),
None => {
"multiple nested fields with the same type must have a `prefix`: \
use `#[sea_orm(nested(prefix = \"...\"))]`"
.to_string()
}
};
let mut err = Error::new_spanned(&field_tokens, msg);
err.combine(Error::new_spanned(e.get(), "first defined here"));
return Err(err);
}
Entry::Vacant(e) => {
e.insert(field_tokens);
}
}
}

fields.push(FromQueryResultItem { typ, ident, alias });
}

Expand Down Expand Up @@ -194,12 +244,5 @@ impl DeriveFromQueryResult {
}

pub fn expand_derive_from_query_result(input: DeriveInput) -> syn::Result<TokenStream> {
let ident_span = input.ident.span();

match DeriveFromQueryResult::new(input) {
Ok(partial_model) => partial_model.expand(),
Err(Error::InputNotStruct) => Ok(quote_spanned! {
ident_span => compile_error!("you can only derive `FromQueryResult` on named struct");
}),
}
DeriveFromQueryResult::new(input)?.expand()
}
95 changes: 78 additions & 17 deletions sea-orm-macros/src/derives/partial_model.rs
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Open in desktop
Original file line number Diff line number Diff line change
@@ -1,6 +1,8 @@
use std::collections::{HashMap, hash_map::Entry};

use heck::ToUpperCamelCase;
use proc_macro2::{Span, TokenStream};
use quote::{format_ident, quote, quote_spanned};
use quote::{ToTokens, format_ident, quote, quote_spanned};
use syn::{
Expr, Meta, Type, ext::IdentExt, punctuated::Punctuated, spanned::Spanned, token::Comma,
};
Expand Down Expand Up @@ -37,6 +39,7 @@ enum ColumnAs {
typ: Type,
field: syn::Ident,
alias: Option<String>,
prefix: Option<String>,
},
Skip(syn::Ident),
}
Expand Down Expand Up @@ -105,6 +108,7 @@ impl DerivePartialModel {
}

let mut column_as_list = Vec::with_capacity(fields.len());
let mut seen_nested: HashMap<(syn::Type, Option<String>), TokenStream> = HashMap::new();

for field in fields {
let field_span = field.span();
Expand All @@ -113,6 +117,7 @@ impl DerivePartialModel {
let mut from_expr = None;
let mut nested = false;
let mut nested_alias = None;
let mut nested_prefix = None;
let mut skip = false;

for attr in field.attrs.iter() {
Expand All @@ -127,6 +132,19 @@ impl DerivePartialModel {
skip = true;
} else if meta.exists("nested") {
nested = true;
} else if let Some(list) = meta.get_list_args("nested") {
nested = true;
for m in list.iter() {
match m.get_as_kv("prefix") {
Some(p) => nested_prefix = Some(p),
None => {
return Err(Error::Syn(syn::Error::new_spanned(
m,
"invalid nested attribute, expected `prefix = \"...\"`",
)));
}
}
}
} else if let Some(s) = meta.get_as_kv("from_col") {
from_col = Some(format_ident!("{}", s.to_upper_camel_case()));
} else if let Some(s) = meta.get_as_kv("from_expr") {
Expand All @@ -138,6 +156,7 @@ impl DerivePartialModel {
}
}

let field_tokens = field.to_token_stream();
let field_name = field.ident.unwrap();

let col_as = match (from_col, from_expr, nested) {
Expand All @@ -155,11 +174,36 @@ impl DerivePartialModel {
expr,
field: field_name,
},
(None, None, true) => ColumnAs::Nested {
typ: field.ty,
field: field_name,
alias: nested_alias,
},
(None, None, true) => {
let key = (field.ty.clone(), nested_prefix.clone());
match seen_nested.entry(key) {
Entry::Occupied(e) => {
let msg = match nested_prefix {
Some(p) => format!(
"multiple nested fields with the same type share prefix \"{p}\""
),
None => {
"multiple nested fields with the same type must have a `prefix`: \
use `#[sea_orm(nested(prefix = \"...\"))]`"
.to_string()
}
};
let mut err = syn::Error::new_spanned(&field_tokens, msg);
err.combine(syn::Error::new_spanned(e.get(), "first defined here"));
return Err(Error::Syn(err));
}
Entry::Vacant(e) => {
e.insert(field_tokens);
}
}

ColumnAs::Nested {
typ: field.ty,
field: field_name,
alias: nested_alias,
prefix: nested_prefix,
}
}
(None, None, false) => {
if entity.is_none() {
return Err(Error::EntityNotSpecified);
Expand Down Expand Up @@ -201,7 +245,9 @@ impl DerivePartialModel {
.iter()
.map(|col_as| FromQueryResultItem {
typ: match col_as {
ColumnAs::Nested { .. } => FqrItemType::Nested,
ColumnAs::Nested { prefix, .. } => FqrItemType::Nested {
prefix: prefix.clone(),
},
ColumnAs::Skip(_) => FqrItemType::Skip,
_ => FqrItemType::Flat,
},
Expand Down Expand Up @@ -320,22 +366,37 @@ impl DerivePartialModel {
};
)
}
ColumnAs::Nested { typ, field, alias } => {
let field = field.unraw().to_string();
ColumnAs::Nested {
typ,
field,
alias,
prefix,
} => {
let field_str = field.unraw().to_string();
let alias_ref: Option<&str> = alias.as_deref();
let alias_arg = match alias_ref {
Some(s) => quote! { Some(#s) },
None => quote! { None },
};
quote!(let #select_ident =
<#typ as sea_orm::PartialModelTrait>::select_cols_nested(#select_ident,
let prefix_expr = match prefix {
Some(p) => quote! {
Some(&if let Some(prefix) = pre {
format!("{prefix}{}_", #field)
} else {
format!("{}_", #field)
}
),
#alias_arg
format!("{prefix}{}", #p)
} else {
#p.to_string()
})
},
None => quote! {
Some(&if let Some(prefix) = pre {
format!("{prefix}{}_", #field_str)
} else {
format!("{}_", #field_str)
})
},
};
quote!(let #select_ident =
<#typ as sea_orm::PartialModelTrait>::select_cols_nested(
#select_ident, #prefix_expr, #alias_arg
);
)
}
Expand Down
10 changes: 10 additions & 0 deletions sea-orm-macros/src/derives/util.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -199,6 +199,7 @@ pub(crate) trait GetMeta {
fn exists(&self, k: &str) -> bool;
fn get_as_kv(&self, k: &str) -> Option<String>;
fn get_as_kv_with_ident(&self) -> Option<(Ident, String)>;
fn get_list_args(&self, name: &str) -> Option<Punctuated<Meta, Comma>>;
}

impl GetMeta for Meta {
Expand Down Expand Up @@ -247,6 +248,15 @@ impl GetMeta for Meta {
path.get_ident()
.map(|ident| (ident.clone(), litstr.value()))
}

fn get_list_args(&self, name: &str) -> Option<Punctuated<Meta, Comma>> {
match self {
Meta::List(list) if list.path.is_ident(name) => list
.parse_args_with(Punctuated::<Meta, Comma>::parse_terminated)
.ok(),
_ => None,
}
}
}

#[cfg(test)]
Expand Down
5 changes: 4 additions & 1 deletion sea-orm-macros/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -708,7 +708,7 @@ pub fn derive_active_enum(input: TokenStream) -> TokenStream {
/// ### Attributes
///
/// - `skip`: will not try to pull this field from the query result. And set it to the default value of the type.
/// - `nested`: allows nesting models. can be any type that implements `FromQueryResult`
/// - `nested`: allows nesting models. can be any type that implements `FromQueryResult`. supports `nested(prefix = "...")` to set an explicit column prefix.
/// - `alias` / `from_alias`: get the value from this column alias
///
/// ### Usage
Expand Down Expand Up @@ -747,6 +747,9 @@ pub fn derive_active_enum(input: TokenStream) -> TokenStream {
/// price: Decimal,
/// #[sea_orm(nested)]
/// baker: Option<cakes_bakers::Model>,
/// // prefix is optional, useful when multiple fields share the same type
/// #[sea_orm(nested(prefix = "reviewer_"))]
/// reviewer: Option<cakes_bakers::Model>,
/// }
/// ```
#[cfg(feature = "derive")]
Expand Down