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fix: using _count in relation selection #143

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Aug 5, 2025
Merged

fix: using _count in relation selection #143

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13 changes: 12 additions & 1 deletion packages/runtime/src/client/crud-types.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -393,7 +393,12 @@ export type SelectInput<
[Key in NonRelationFields<Schema, Model>]?: true;
} & (AllowRelation extends true ? IncludeInput<Schema, Model> : {}) & // relation fields
// relation count
(AllowCount extends true ? { _count?: SelectCount<Schema, Model> } : {});
(AllowCount extends true
? // _count is only allowed if the model has to-many relations
HasToManyRelations<Schema, Model> extends true
? { _count?: SelectCount<Schema, Model> }
: {}
: {});

type SelectCount<Schema extends SchemaDef, Model extends GetModels<Schema>> =
| true
Expand Down Expand Up @@ -1181,4 +1186,10 @@ type NonOwnedRelationFields<Schema extends SchemaDef, Model extends GetModels<Sc
: Key]: true;
};

type HasToManyRelations<Schema extends SchemaDef, Model extends GetModels<Schema>> = keyof {
[Key in RelationFields<Schema, Model> as FieldIsArray<Schema, Model, Key> extends true ? Key : never]: true;
} extends never
? false
: true;

// #endregion
50 changes: 50 additions & 0 deletions packages/runtime/src/client/crud/dialects/base.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -847,6 +847,56 @@ export abstract class BaseCrudDialect<Schema extends SchemaDef> {
return query;
}

buildCountJson(model: string, eb: ExpressionBuilder<any, any>, parentAlias: string, payload: any) {
const modelDef = requireModel(this.schema, model);
const toManyRelations = Object.entries(modelDef.fields).filter(([, field]) => field.relation && field.array);

const selections =
payload === true
? {
select: toManyRelations.reduce(
(acc, [field]) => {
acc[field] = true;
return acc;
},
{} as Record<string, boolean>,
),
}
: payload;

const jsonObject: Record<string, Expression<any>> = {};

for (const [field, value] of Object.entries(selections.select)) {
const fieldDef = requireField(this.schema, model, field);
const fieldModel = fieldDef.type;
const joinPairs = buildJoinPairs(this.schema, model, parentAlias, field, fieldModel);

// build a nested query to count the number of records in the relation
let fieldCountQuery = eb.selectFrom(fieldModel).select(eb.fn.countAll().as(`_count$${field}`));

// join conditions
for (const [left, right] of joinPairs) {
fieldCountQuery = fieldCountQuery.whereRef(left, '=', right);
}

// merge _count filter
if (
value &&
typeof value === 'object' &&
'where' in value &&
value.where &&
typeof value.where === 'object'
) {
const filter = this.buildFilter(eb, fieldModel, fieldModel, value.where);
fieldCountQuery = fieldCountQuery.where(filter);
}

jsonObject[field] = fieldCountQuery;
}

return this.buildJsonObject(eb, jsonObject);
}

// #endregion

// #region utils
Expand Down
30 changes: 20 additions & 10 deletions packages/runtime/src/client/crud/dialects/postgresql.ts
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Expand Up @@ -200,7 +200,7 @@ export class PostgresCrudDialect<Schema extends SchemaDef> extends BaseCrudDiale
relationField: string,
eb: ExpressionBuilder<any, any>,
payload: true | FindArgs<Schema, GetModels<Schema>, true>,
parentName: string,
parentAlias: string,
) {
const relationModelDef = requireModel(this.schema, relationModel);
const objArgs: Array<
Expand Down Expand Up @@ -238,14 +238,24 @@ export class PostgresCrudDialect<Schema extends SchemaDef> extends BaseCrudDiale
objArgs.push(
...Object.entries(payload.select)
.filter(([, value]) => value)
.map(([field]) => {
const fieldDef = requireField(this.schema, relationModel, field);
const fieldValue = fieldDef.relation
? // reference the synthesized JSON field
eb.ref(`${parentName}$${relationField}$${field}.$j`)
: // reference a plain field
buildFieldRef(this.schema, relationModel, field, this.options, eb);
return [sql.lit(field), fieldValue];
.map(([field, value]) => {
if (field === '_count') {
const subJson = this.buildCountJson(
relationModel as GetModels<Schema>,
eb,
`${parentAlias}$${relationField}`,
value,
);
return [sql.lit(field), subJson];
} else {
const fieldDef = requireField(this.schema, relationModel, field);
const fieldValue = fieldDef.relation
? // reference the synthesized JSON field
eb.ref(`${parentAlias}$${relationField}$${field}.$j`)
: // reference a plain field
buildFieldRef(this.schema, relationModel, field, this.options, eb);
return [sql.lit(field), fieldValue];
}
})
.flatMap((v) => v),
);
Expand All @@ -259,7 +269,7 @@ export class PostgresCrudDialect<Schema extends SchemaDef> extends BaseCrudDiale
.map(([field]) => [
sql.lit(field),
// reference the synthesized JSON field
eb.ref(`${parentName}$${relationField}$${field}.$j`),
eb.ref(`${parentAlias}$${relationField}$${field}.$j`),
])
.flatMap((v) => v),
);
Expand Down
42 changes: 26 additions & 16 deletions packages/runtime/src/client/crud/dialects/sqlite.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -67,14 +67,14 @@ export class SqliteCrudDialect<Schema extends SchemaDef> extends BaseCrudDialect
model: string,
eb: ExpressionBuilder<any, any>,
relationField: string,
parentName: string,
parentAlias: string,
payload: true | FindArgs<Schema, GetModels<Schema>, true>,
) {
const relationFieldDef = requireField(this.schema, model, relationField);
const relationModel = relationFieldDef.type as GetModels<Schema>;
const relationModelDef = requireModel(this.schema, relationModel);

const subQueryName = `${parentName}$${relationField}`;
const subQueryName = `${parentAlias}$${relationField}`;

let tbl = eb.selectFrom(() => {
let subQuery = this.buildSelectModel(eb, relationModel);
Expand Down Expand Up @@ -129,18 +129,18 @@ export class SqliteCrudDialect<Schema extends SchemaDef> extends BaseCrudDialect
eb
.selectFrom(m2m.joinTable)
.select(`${m2m.joinTable}.${m2m.otherFkName}`)
.whereRef(`${parentName}.${parentIds[0]}`, '=', `${m2m.joinTable}.${m2m.parentFkName}`),
.whereRef(`${parentAlias}.${parentIds[0]}`, '=', `${m2m.joinTable}.${m2m.parentFkName}`),
),
);
} else {
const { keyPairs, ownedByModel } = getRelationForeignKeyFieldPairs(this.schema, model, relationField);
keyPairs.forEach(({ fk, pk }) => {
if (ownedByModel) {
// the parent model owns the fk
subQuery = subQuery.whereRef(`${relationModel}.${pk}`, '=', `${parentName}.${fk}`);
subQuery = subQuery.whereRef(`${relationModel}.${pk}`, '=', `${parentAlias}.${fk}`);
} else {
// the relation side owns the fk
subQuery = subQuery.whereRef(`${relationModel}.${fk}`, '=', `${parentName}.${pk}`);
subQuery = subQuery.whereRef(`${relationModel}.${fk}`, '=', `${parentAlias}.${pk}`);
}
});
}
Expand Down Expand Up @@ -183,21 +183,31 @@ export class SqliteCrudDialect<Schema extends SchemaDef> extends BaseCrudDialect
...Object.entries<any>(payload.select)
.filter(([, value]) => value)
.map(([field, value]) => {
const fieldDef = requireField(this.schema, relationModel, field);
if (fieldDef.relation) {
const subJson = this.buildRelationJSON(
if (field === '_count') {
const subJson = this.buildCountJson(
relationModel as GetModels<Schema>,
eb,
field,
`${parentName}$${relationField}`,
`${parentAlias}$${relationField}`,
value,
);
return [sql.lit(field), subJson as ArgsType];
return [sql.lit(field), subJson];
} else {
return [
sql.lit(field),
buildFieldRef(this.schema, relationModel, field, this.options, eb) as ArgsType,
];
const fieldDef = requireField(this.schema, relationModel, field);
if (fieldDef.relation) {
const subJson = this.buildRelationJSON(
relationModel as GetModels<Schema>,
eb,
field,
`${parentAlias}$${relationField}`,
value,
);
return [sql.lit(field), subJson];
} else {
return [
sql.lit(field),
buildFieldRef(this.schema, relationModel, field, this.options, eb) as ArgsType,
];
}
}
})
.flatMap((v) => v),
Expand All @@ -214,7 +224,7 @@ export class SqliteCrudDialect<Schema extends SchemaDef> extends BaseCrudDialect
relationModel as GetModels<Schema>,
eb,
field,
`${parentName}$${relationField}`,
`${parentAlias}$${relationField}`,
value,
);
return [sql.lit(field), subJson];
Expand Down
53 changes: 1 addition & 52 deletions packages/runtime/src/client/crud/operations/base.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,6 @@ import {
UpdateResult,
type Compilable,
type IsolationLevel,
type Expression as KyselyExpression,
type QueryResult,
type SelectQueryBuilder,
} from 'kysely';
Expand All @@ -31,7 +30,6 @@ import { InternalError, NotFoundError, QueryError } from '../../errors';
import type { ToKysely } from '../../query-builder';
import {
buildFieldRef,
buildJoinPairs,
ensureArray,
extractIdFields,
flattenCompoundUniqueFilters,
Expand Down Expand Up @@ -298,56 +296,7 @@ export abstract class BaseOperationHandler<Schema extends SchemaDef> {
parentAlias: string,
payload: any,
) {
const modelDef = requireModel(this.schema, model);
const toManyRelations = Object.entries(modelDef.fields).filter(([, field]) => field.relation && field.array);

const selections =
payload === true
? {
select: toManyRelations.reduce(
(acc, [field]) => {
acc[field] = true;
return acc;
},
{} as Record<string, boolean>,
),
}
: payload;

const eb = expressionBuilder<any, any>();
const jsonObject: Record<string, KyselyExpression<any>> = {};

for (const [field, value] of Object.entries(selections.select)) {
const fieldDef = requireField(this.schema, model, field);
const fieldModel = fieldDef.type;
const joinPairs = buildJoinPairs(this.schema, model, parentAlias, field, fieldModel);

// build a nested query to count the number of records in the relation
let fieldCountQuery = eb.selectFrom(fieldModel).select(eb.fn.countAll().as(`_count$${field}`));

// join conditions
for (const [left, right] of joinPairs) {
fieldCountQuery = fieldCountQuery.whereRef(left, '=', right);
}

// merge _count filter
if (
value &&
typeof value === 'object' &&
'where' in value &&
value.where &&
typeof value.where === 'object'
) {
const filter = this.dialect.buildFilter(eb, fieldModel, fieldModel, value.where);
fieldCountQuery = fieldCountQuery.where(filter);
}

jsonObject[field] = fieldCountQuery;
}

query = query.select((eb) => this.dialect.buildJsonObject(eb, jsonObject).as('_count'));

return query;
return query.select((eb) => this.dialect.buildCountJson(model, eb, parentAlias, payload).as('_count'));
}

private buildCursorFilter(
Expand Down
6 changes: 3 additions & 3 deletions packages/runtime/src/client/crud/validator.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -544,17 +544,17 @@ export class InputValidator<Schema extends SchemaDef> {
}
}

const toManyRelations = Object.entries(modelDef.fields).filter(([, value]) => value.relation && value.array);
const toManyRelations = Object.values(modelDef.fields).filter((def) => def.relation && def.array);

if (toManyRelations.length > 0) {
fields['_count'] = z
.union([
z.literal(true),
z.object(
toManyRelations.reduce(
(acc, [name, fieldDef]) => ({
(acc, fieldDef) => ({
...acc,
[name]: z
[fieldDef.name]: z
.union([
z.boolean(),
z.object({
Expand Down
16 changes: 8 additions & 8 deletions packages/runtime/src/client/query-utils.ts
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Expand Up @@ -97,23 +97,23 @@ export function getRelationForeignKeyFieldPairs(schema: SchemaDef, model: string
}

export function isScalarField(schema: SchemaDef, model: string, field: string): boolean {
const fieldDef = requireField(schema, model, field);
return !fieldDef.relation && !fieldDef.foreignKeyFor;
const fieldDef = getField(schema, model, field);
return !fieldDef?.relation && !fieldDef?.foreignKeyFor;
}

export function isForeignKeyField(schema: SchemaDef, model: string, field: string): boolean {
const fieldDef = requireField(schema, model, field);
return !!fieldDef.foreignKeyFor;
const fieldDef = getField(schema, model, field);
return !!fieldDef?.foreignKeyFor;
}

export function isRelationField(schema: SchemaDef, model: string, field: string): boolean {
const fieldDef = requireField(schema, model, field);
return !!fieldDef.relation;
const fieldDef = getField(schema, model, field);
return !!fieldDef?.relation;
}

export function isInheritedField(schema: SchemaDef, model: string, field: string): boolean {
const fieldDef = requireField(schema, model, field);
return !!fieldDef.originModel;
const fieldDef = getField(schema, model, field);
return !!fieldDef?.originModel;
}

export function getUniqueFields(schema: SchemaDef, model: string) {
Expand Down
25 changes: 25 additions & 0 deletions packages/runtime/test/client-api/find.test.ts
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Expand Up @@ -832,6 +832,31 @@ describe.each(createClientSpecs(PG_DB_NAME))('Client find tests for $provider',
_count: { posts: 2 },
});

await expect(
client.user.findUnique({
where: { id: user1.id },
select: {
id: true,
posts: {
select: { _count: true },
},
},
}),
).resolves.toMatchObject({
id: user1.id,
posts: [{ _count: { comments: 0 } }, { _count: { comments: 0 } }],
});

client.comment.findFirst({
// @ts-expect-error Comment has no to-many relations to count
select: { _count: true },
});

client.post.findFirst({
// @ts-expect-error Comment has no to-many relations to count
select: { comments: { _count: true } },
});

await expect(
client.user.findUnique({
where: { id: user1.id },
Expand Down