feat: relation field and picker

internal/domain/contenttype/contentTypeDomain.go

@@ -13,6 +13,7 @@ var (
 	ErrInvalidIcon         = errors.New("invalid content type icon")
 	ErrInvalidField        = errors.New("invalid field")
 	ErrHasEntries          = errors.New("the content type still has entries")
+	ErrReferenced          = errors.New("the content type is the target of a relation field")
 	ErrSchemaIncompatible  = errors.New("the schema is incompatible with the stored entries")
 )
 
@@ -26,6 +27,7 @@ const (
 	TypeDate     FieldType = "date"
 	TypeSelect   FieldType = "select"
 	TypeMedia    FieldType = "media"
+	TypeRelation FieldType = "relation"
 )
 
 const (
@@ -54,6 +56,7 @@ type Field struct {
 	Min      any       `json:"min"`
 	Max      any       `json:"max"`
 	Options  []string  `json:"options"`
+	Relation *Relation `json:"relation"`
 }
 
 type ContentType struct {

internal/domain/contenttype/fieldKinds.go

@@ -21,6 +21,7 @@ var kinds = map[FieldType]kind{
 	TypeDate:     {accepts: isDate, measure: dateDays, bound: dateDays, unique: true},
 	TypeSelect:   {accepts: isString, unique: true},
 	TypeMedia:    {accepts: isMediaID},
+	TypeRelation: {},
 }
 
 func MediaID(value any) (uint32, bool) {

internal/domain/contenttype/fieldSchema.go

@@ -63,7 +63,7 @@ func (f Field) validSchema() bool {
 	if f.Unique && !fieldKind.unique {
 		return false
 	}
-	return f.validOptions() && f.validBounds(fieldKind) && f.validDefault()
+	return f.validRelation() && f.validOptions() && f.validBounds(fieldKind) && f.validDefault()
 }
 
 func (f Field) validOptions() bool {
@@ -109,7 +109,7 @@ func (f Field) validDefault() bool {
 	if f.Default == nil {
 		return true
 	}
-	if f.Type == TypeMedia {
+	if f.Type == TypeMedia || f.Type == TypeRelation {
 		return false
 	}
 	return !f.Unique && f.Violation(f.Default) == ""

internal/domain/contenttype/fieldValue.go

@@ -3,6 +3,9 @@ package contenttype
 import "slices"
 
 func (f Field) Violation(value any) string {
+	if f.Type == TypeRelation {
+		return f.relationViolation(value)
+	}
 	fieldKind, known := kinds[f.Type]
 	if !known || !fieldKind.accepts(value) {
 		return RuleType

internal/domain/contenttype/relationField.go

@@ -0,0 +1,134 @@
+package contenttype
+
+const MaxRelationIDs = 50
+
+type RelationKind string
+
+const (
+	RelationOneToOne   RelationKind = "one_to_one"
+	RelationOneToMany  RelationKind = "one_to_many"
+	RelationManyToMany RelationKind = "many_to_many"
+)
+
+type Relation struct {
+	ContentType string       `json:"content_type"`
+	Kind        RelationKind `json:"kind"`
+}
+
+func (r Relation) validKind() bool {
+	return r.Kind == RelationOneToOne || r.Kind == RelationOneToMany || r.Kind == RelationManyToMany
+}
+
+func (f Field) validRelation() bool {
+	if f.Type != TypeRelation {
+		return f.Relation == nil
+	}
+	return f.Relation != nil && f.Relation.ContentType != "" && f.Relation.validKind()
+}
+
+func (f Field) IsRelation() bool {
+	return f.Type == TypeRelation && f.Relation != nil
+}
+
+func (f Field) HoldsManyRelations() bool {
+	return f.IsRelation() && f.Relation.Kind == RelationManyToMany
+}
+
+func (f Field) IsExclusiveRelation() bool {
+	return f.IsRelation() && f.Relation.Kind == RelationOneToOne
+}
+
+func (f Field) RelationIDs(value any) ([]uint32, bool) {
+	if value == nil {
+		return []uint32{}, true
+	}
+	if !f.HoldsManyRelations() {
+		id, ok := MediaID(value)
+		if !ok {
+			return nil, false
+		}
+		return []uint32{id}, true
+	}
+	return manyRelationIDs(value)
+}
+
+func manyRelationIDs(value any) ([]uint32, bool) {
+	var items []any
+	switch typed := value.(type) {
+	case []any:
+		items = typed
+	case []uint32:
+		for _, id := range typed {
+			items = append(items, id)
+		}
+	default:
+		return nil, false
+	}
+	if len(items) > MaxRelationIDs {
+		return nil, false
+	}
+	ids := make([]uint32, 0, len(items))
+	seen := make(map[uint32]bool, len(items))
+	for _, item := range items {
+		id, ok := MediaID(item)
+		if !ok || seen[id] {
+			return nil, false
+		}
+		seen[id] = true
+		ids = append(ids, id)
+	}
+	return ids, true
+}
+
+func (f Field) relationViolation(value any) string {
+	if _, ok := f.RelationIDs(value); !ok {
+		return RuleType
+	}
+	return ""
+}
+
+func EmptyRelation(field Field, value any) bool {
+	if !field.HoldsManyRelations() {
+		return false
+	}
+	ids, ok := field.RelationIDs(value)
+	return ok && len(ids) == 0
+}
+
+type RelationRef struct {
+	Field Field
+	IDs   []uint32
+}
+
+func RelationRefs(fields []Field, data map[string]any) []RelationRef {
+	var refs []RelationRef
+	for _, field := range RelationFields(fields) {
+		if ids, ok := field.RelationIDs(data[field.Key]); ok && len(ids) > 0 {
+			refs = append(refs, RelationRef{Field: field, IDs: ids})
+		}
+	}
+	return refs
+}
+
+func RelationFields(fields []Field) []Field {
+	var relations []Field
+	for _, field := range fields {
+		if field.IsRelation() {
+			relations = append(relations, field)
+		}
+	}
+	return relations
+}
+
+func ReferencesType(fields []Field, key string) bool {
+	for _, field := range RelationFields(fields) {
+		if field.Relation.ContentType == key {
+			return true
+		}
+	}
+	return false
+}
+
+func SameRelation(left Field, right Field) bool {
+	return left.IsRelation() && right.IsRelation() && *left.Relation == *right.Relation
+}

internal/domain/entry/entryData.go

@@ -2,8 +2,11 @@ package entry
 
 import (
 	"RenewCMS/internal/domain/contenttype"
+	"fmt"
 	"reflect"
 	"sort"
+	"strconv"
+	"strings"
 )
 
 func SameValue(left any, right any) bool {
@@ -49,7 +52,7 @@ func Validate(fields []contenttype.Field, data map[string]any) error {
 
 func validateField(field contenttype.Field, data map[string]any) error {
 	value := data[field.Key]
-	if value == nil {
+	if value == nil || contenttype.EmptyRelation(field, value) {
 		if field.Required {
 			return InvalidField(field.Key, RuleRequired)
 		}
@@ -82,7 +85,7 @@ func firstUnknownField(fields []contenttype.Field, data map[string]any) error {
 func UniqueValues(fields []contenttype.Field, data map[string]any) []UniqueValue {
 	var values []UniqueValue
 	for _, field := range fields {
-		if value := data[field.Key]; field.Unique && value != nil {
+		if value := data[field.Key]; (field.Unique || field.IsExclusiveRelation()) && value != nil {
 			values = append(values, UniqueValue{Key: field.Key, Value: value})
 		}
 	}
@@ -103,3 +106,38 @@ func MissingMedia(field contenttype.Field, unchanged bool) error {
 	}
 	return InvalidField(field.Key, contenttype.RuleType)
 }
+
+func RelationIDs(fields []contenttype.Field, data map[string]any) map[string]map[uint32]bool {
+	ids := map[string]map[uint32]bool{}
+	for _, ref := range contenttype.RelationRefs(fields, data) {
+		held := make(map[uint32]bool, len(ref.IDs))
+		for _, id := range ref.IDs {
+			held[id] = true
+		}
+		ids[ref.Field.Key] = held
+	}
+	return ids
+}
+
+func MissingRelation(field contenttype.Field, unchanged bool) error {
+	return MissingMedia(field, unchanged)
+}
+
+func MatchesQuery(fields []contenttype.Field, data map[string]any, query string) bool {
+	if len(fields) == 0 {
+		return false
+	}
+	return strings.Contains(strings.ToLower(displayText(data[fields[0].Key])), strings.ToLower(query))
+}
+
+func displayText(value any) string {
+	switch typed := value.(type) {
+	case nil:
+		return ""
+	case string:
+		return typed
+	case float64:
+		return strconv.FormatFloat(typed, 'f', -1, 64)
+	}
+	return fmt.Sprint(value)
+}

internal/infrastructure/useCases/CreateContentType.go

@@ -37,6 +37,9 @@ func (u *CreateContentTypeUseCase) Create(command CreateContentTypeCommand) (con
 	if err != nil {
 		return contenttype.ContentType{}, err
 	}
+	if err := ensureRelationTargets(u.contentTypes, command.Key, fields); err != nil {
+		return contenttype.ContentType{}, err
+	}
 	if err := u.ensureKeyFree(command.Key); err != nil {
 		return contenttype.ContentType{}, err
 	}

internal/infrastructure/useCases/CreateEntry.go

@@ -36,6 +36,10 @@ func (u *CreateEntryUseCase) Create(command CreateEntryCommand) (TypedEntry, err
 	if err := ensureMediaExists(u.images, owner, data, nil); err != nil {
 		return TypedEntry{}, err
 	}
+	resolvers := newEntryResolvers(u.images, u.contentTypes, u.entries)
+	if err := ensureRelationsExist(resolvers.relations, owner, data, nil); err != nil {
+		return TypedEntry{}, err
+	}
 	if err := ensureUnique(u.entries, owner, data, 0); err != nil {
 		return TypedEntry{}, err
 	}
@@ -51,5 +55,5 @@ func (u *CreateEntryUseCase) Create(command CreateEntryCommand) (TypedEntry, err
 	if err != nil {
 		return TypedEntry{}, err
 	}
-	return typedEntry(owner, stored, newMediaResolver(u.images))
+	return typedEntry(owner, stored, resolvers)
 }

internal/infrastructure/useCases/DeleteContentType.go

@@ -19,6 +19,15 @@ func (u *DeleteContentTypeUseCase) Delete(key string) error {
 	if err != nil {
 		return err
 	}
+	types, err := u.contentTypes.List()
+	if err != nil {
+		return err
+	}
+	for _, other := range types {
+		if other.ID != target.ID && contenttype.ReferencesType(other.Fields, target.Key) {
+			return contenttype.ErrReferenced
+		}
+	}
 	count, err := u.entries.CountByContentType(target.ID)
 	if err != nil {
 		return err

internal/infrastructure/useCases/GetEntry.go

@@ -25,5 +25,5 @@ func (u *GetEntryUseCase) Get(contentTypeKey string, id uint32) (TypedEntry, err
 	if err != nil {
 		return TypedEntry{}, err
 	}
-	return typedEntry(owner, found, newMediaResolver(u.images))
+	return typedEntry(owner, found, newEntryResolvers(u.images, u.contentTypes, u.entries))
 }

internal/infrastructure/useCases/ListEntries.go

@@ -4,6 +4,7 @@ import (
 	"RenewCMS/internal/domain/contenttype"
 	"RenewCMS/internal/domain/entry"
 	"RenewCMS/internal/domain/image"
+	"strings"
 )
 
 type ListEntriesUseCase struct {
@@ -17,6 +18,7 @@ type ListEntriesCommand struct {
 	Page           int
 	Size           int
 	Sort           entry.Sort
+	Query          string
 }
 
 type EntryPage struct {
@@ -41,12 +43,12 @@ func (u *ListEntriesUseCase) ListPage(command ListEntriesCommand) (EntryPage, er
 	if err != nil {
 		return EntryPage{}, err
 	}
-	found, err := u.entries.ListPage(entry.Filters{ContentTypeID: owner.ID, Page: command.Page, Size: command.Size, Sort: command.Sort})
+	found, err := u.page(owner, command)
 	if err != nil {
 		return EntryPage{}, err
 	}
 	items := make([]TypedEntry, 0, len(found.Items))
-	resolver := newMediaResolver(u.images)
+	resolver := newEntryResolvers(u.images, u.contentTypes, u.entries)
 	for _, record := range found.Items {
 		typed, err := typedEntry(owner, record, resolver)
 		if err != nil {
@@ -56,3 +58,25 @@ func (u *ListEntriesUseCase) ListPage(command ListEntriesCommand) (EntryPage, er
 	}
 	return EntryPage{Items: items, Total: found.Total, Page: command.Page, Size: command.Size}, nil
 }
+
+func (u *ListEntriesUseCase) page(owner contenttype.ContentType, command ListEntriesCommand) (entry.PageResult, error) {
+	query := strings.TrimSpace(command.Query)
+	if query == "" {
+		return u.entries.ListPage(entry.Filters{ContentTypeID: owner.ID, Page: command.Page, Size: command.Size, Sort: command.Sort})
+	}
+	all, err := u.entries.ListPage(entry.Filters{ContentTypeID: owner.ID, Unpaged: true, Sort: command.Sort})
+	if err != nil {
+		return entry.PageResult{}, err
+	}
+	matching := make([]entry.Entry, 0, len(all.Items))
+	for _, record := range all.Items {
+		if entry.MatchesQuery(owner.Fields, record.Data, query) {
+			matching = append(matching, record)
+		}
+	}
+	pageNumber := max(command.Page, 1)
+	size := max(command.Size, 0)
+	start := min((pageNumber-1)*size, len(matching))
+	end := min(start+size, len(matching))
+	return entry.PageResult{Items: matching[start:end], Total: len(matching)}, nil
+}

internal/infrastructure/useCases/UpdateContentType.go

@@ -39,6 +39,12 @@ func (u *UpdateContentTypeUseCase) Update(command UpdateContentTypeCommand) (con
 	if err != nil {
 		return contenttype.ContentType{}, err
 	}
+	if relationShapeChanged(current.Fields, fields) {
+		return contenttype.ContentType{}, contenttype.ErrInvalidField
+	}
+	if err := ensureRelationTargets(u.contentTypes, current.Key, fields); err != nil {
+		return contenttype.ContentType{}, err
+	}
 	stored, err := u.storedEntries(current.ID)
 	if err != nil {
 		return contenttype.ContentType{}, err

internal/infrastructure/useCases/UpdateEntry.go

@@ -40,6 +40,10 @@ func (u *UpdateEntryUseCase) Update(command UpdateEntryCommand) (TypedEntry, err
 	if err := ensureMediaExists(u.images, owner, command.Data, current.Data); err != nil {
 		return TypedEntry{}, err
 	}
+	resolvers := newEntryResolvers(u.images, u.contentTypes, u.entries)
+	if err := ensureRelationsExist(resolvers.relations, owner, command.Data, current.Data); err != nil {
+		return TypedEntry{}, err
+	}
 	if err := ensureUnique(u.entries, owner, command.Data, current.ID); err != nil {
 		return TypedEntry{}, err
 	}
@@ -50,5 +54,5 @@ func (u *UpdateEntryUseCase) Update(command UpdateEntryCommand) (TypedEntry, err
 	if err != nil {
 		return TypedEntry{}, err
 	}
-	return typedEntry(owner, stored, newMediaResolver(u.images))
+	return typedEntry(owner, stored, resolvers)
 }

internal/infrastructure/useCases/entryRelation.go

@@ -0,0 +1,168 @@
+package useCases
+
+import (
+	"RenewCMS/internal/domain/contenttype"
+	"RenewCMS/internal/domain/entry"
+	"errors"
+)
+
+type EntryFirstField struct {
+	Key   string
+	Type  contenttype.FieldType
+	Value any
+}
+
+type EntryRelation struct {
+	ID          uint32
+	Missing     bool
+	ContentType string
+	FirstField  EntryFirstField
+}
+
+type EntryRelations struct {
+	Many  bool
+	Items []EntryRelation
+}
+
+type targetEntryKey struct {
+	contentType string
+	id          uint32
+}
+
+type relationResolver struct {
+	contentTypes contenttype.Repository
+	entries      entry.Repository
+	types        map[string]*contenttype.ContentType
+	found        map[targetEntryKey]EntryRelation
+}
+
+func newRelationResolver(contentTypes contenttype.Repository, entries entry.Repository) *relationResolver {
+	return &relationResolver{contentTypes: contentTypes, entries: entries, types: map[string]*contenttype.ContentType{}, found: map[targetEntryKey]EntryRelation{}}
+}
+
+func (r *relationResolver) resolve(owner contenttype.ContentType, record entry.Entry) (map[string]EntryRelations, error) {
+	resolved := map[string]EntryRelations{}
+	for _, ref := range contenttype.RelationRefs(owner.Fields, record.Data) {
+		items := make([]EntryRelation, 0, len(ref.IDs))
+		for _, id := range ref.IDs {
+			item, err := r.lookup(ref.Field.Relation.ContentType, id)
+			if err != nil {
+				return nil, err
+			}
+			items = append(items, item)
+		}
+		resolved[ref.Field.Key] = EntryRelations{Many: ref.Field.HoldsManyRelations(), Items: items}
+	}
+	return resolved, nil
+}
+
+func (r *relationResolver) targetType(key string) (*contenttype.ContentType, error) {
+	if cached, found := r.types[key]; found {
+		return cached, nil
+	}
+	target, err := r.contentTypes.GetByKey(key)
+	if errors.Is(err, contenttype.ErrContentTypeNotFound) {
+		r.types[key] = nil
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	r.types[key] = &target
+	return &target, nil
+}
+
+func (r *relationResolver) lookup(typeKey string, id uint32) (EntryRelation, error) {
+	cacheKey := targetEntryKey{typeKey, id}
+	if cached, found := r.found[cacheKey]; found {
+		return cached, nil
+	}
+	target, err := r.fetch(typeKey, id)
+	if err != nil {
+		return EntryRelation{}, err
+	}
+	r.found[cacheKey] = target
+	return target, nil
+}
+
+func (r *relationResolver) fetch(typeKey string, id uint32) (EntryRelation, error) {
+	missing := EntryRelation{ID: id, Missing: true}
+	target, err := r.targetType(typeKey)
+	if err != nil || target == nil || len(target.Fields) == 0 {
+		return missing, err
+	}
+	record, err := r.entries.Get(target.ID, id)
+	if errors.Is(err, entry.ErrEntryNotFound) {
+		return missing, nil
+	}
+	if err != nil {
+		return EntryRelation{}, err
+	}
+	first := target.Fields[0]
+	return EntryRelation{ID: id, ContentType: typeKey, FirstField: EntryFirstField{Key: first.Key, Type: first.Type, Value: record.Data[first.Key]}}, nil
+}
+
+func (r *relationResolver) exists(typeKey string, id uint32) (bool, error) {
+	target, err := r.targetType(typeKey)
+	if err != nil || target == nil || len(target.Fields) == 0 {
+		return false, err
+	}
+	_, err = r.entries.Get(target.ID, id)
+	if errors.Is(err, entry.ErrEntryNotFound) {
+		return false, nil
+	}
+	return err == nil, err
+}
+
+func ensureRelationsExist(resolver *relationResolver, owner contenttype.ContentType, data map[string]any, stored map[string]any) error {
+	storedIDs := entry.RelationIDs(owner.Fields, stored)
+	for _, ref := range contenttype.RelationRefs(owner.Fields, data) {
+		for _, id := range ref.IDs {
+			unchanged := stored != nil && storedIDs[ref.Field.Key][id]
+			if unchanged && !ref.Field.Required {
+				continue
+			}
+			exists, err := resolver.exists(ref.Field.Relation.ContentType, id)
+			if err != nil {
+				return err
+			}
+			if !exists {
+				return entry.MissingRelation(ref.Field, unchanged)
+			}
+		}
+	}
+	return nil
+}
+
+func ensureRelationTargets(contentTypes contenttype.Repository, ownerKey string, fields []contenttype.Field) error {
+	for _, field := range contenttype.RelationFields(fields) {
+		target := field.Relation.ContentType
+		if target == ownerKey {
+			if field.IsExclusiveRelation() {
+				return contenttype.ErrInvalidField
+			}
+			continue
+		}
+		_, err := contentTypes.GetByKey(target)
+		if errors.Is(err, contenttype.ErrContentTypeNotFound) {
+			return contenttype.ErrInvalidField
+		}
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func relationShapeChanged(previous []contenttype.Field, next []contenttype.Field) bool {
+	nextByKey := make(map[string]contenttype.Field, len(next))
+	for _, field := range next {
+		nextByKey[field.Key] = field
+	}
+	for _, field := range contenttype.RelationFields(previous) {
+		if replacement, kept := nextByKey[field.Key]; kept && !contenttype.SameRelation(field, replacement) {
+			return true
+		}
+	}
+	return false
+}

internal/infrastructure/useCases/entrySupport.go

@@ -11,15 +11,29 @@ type TypedEntry struct {
 	entry.Entry
 	ContentTypeKey string
 	Media          map[string]EntryMedia
+	Relations      map[string]EntryRelations
 }
 
-func typedEntry(owner contenttype.ContentType, record entry.Entry, resolver *mediaResolver) (TypedEntry, error) {
+type entryResolvers struct {
+	media     *mediaResolver
+	relations *relationResolver
+}
+
+func newEntryResolvers(images image.Repository, contentTypes contenttype.Repository, entries entry.Repository) *entryResolvers {
+	return &entryResolvers{media: newMediaResolver(images), relations: newRelationResolver(contentTypes, entries)}
+}
+
+func typedEntry(owner contenttype.ContentType, record entry.Entry, resolvers *entryResolvers) (TypedEntry, error) {
 	record.Data = entry.Project(owner.Fields, record.Data)
-	media, err := resolver.resolve(owner, record)
+	media, err := resolvers.media.resolve(owner, record)
 	if err != nil {
 		return TypedEntry{}, err
 	}
-	return TypedEntry{Entry: record, ContentTypeKey: owner.Key, Media: media}, nil
+	relations, err := resolvers.relations.resolve(owner, record)
+	if err != nil {
+		return TypedEntry{}, err
+	}
+	return TypedEntry{Entry: record, ContentTypeKey: owner.Key, Media: media, Relations: relations}, nil
 }
 
 func ensureMediaExists(images image.Repository, owner contenttype.ContentType, data map[string]any, stored map[string]any) error {