diamond-orm/relationship.go

package orm

import (
	"fmt"
	"reflect"
	"strings"
)

type RelationshipType int

const (
	HasOne RelationshipType = iota
	HasMany
	ManyToMany
)

type Relationship struct {
	Type         RelationshipType
	Model        *Model
	FieldName    string
	Idx          int
	RelatedType  reflect.Type
	RelatedModel *Model
	Kind         reflect.Kind // field kind (struct, slice, ...)
	m2mInverse   *Relationship
}

func (r *Relationship) JoinTable() string {
	return r.Model.TableName + "_" + r.RelatedModel.TableName
}

func (r *Relationship) JoinField() string {
	isMany := r.Type == HasMany //|| r.Type == ManyToMany
	if isMany && r.Model.embeddedIsh {
		return r.Model.Name + r.FieldName + "ID"
	} else if isMany && !r.Model.embeddedIsh && r.m2mInverse == nil {
		return r.Model.Name + "ID"
	} else if r.Type == ManyToMany && !r.Model.embeddedIsh {
		return r.RelatedModel.Name + "ID"
	}
	return r.FieldName + "ID"
}

func (r *Relationship) aliasThingy() string {
	return pascalToSnakeCase(r.Model.Name + "." + r.FieldName)
}

func (r *Relationship) relatedAlias() string {
	return pascalToSnakeCase(r.RelatedModel.Name + "." + r.FieldName)
}

func (r *Relationship) m2mIsh() bool {
	return r.Model.embeddedIsh && !r.RelatedModel.embeddedIsh && r.Type == HasMany
}

func (r *Relationship) joinInsert(v reflect.Value, e *Query, pfk any) error {
	if r.Type != ManyToMany &&
		!r.m2mIsh() {
		return nil
	}
	ichild := v
	for ichild.Kind() == reflect.Ptr {
		ichild = ichild.Elem()
	}
	if ichild.Kind() == reflect.Struct {
		jtable := r.JoinTable()
		jargs := make([]any, 0)
		jcols := make([]string, 0)
		jcols = append(jcols, fmt.Sprintf("%s_%s",
			r.Model.TableName, pascalToSnakeCase(r.FieldName),
		))
		jargs = append(jargs, pfk)

		jcols = append(jcols, r.RelatedModel.TableName+"_id")
		jargs = append(jargs, ichild.FieldByName(r.RelatedModel.IDField).Interface())
		var ecnt int
		e.tx.QueryRow(e.ctx,
			fmt.Sprintf("SELECT count(*) from %s where %s = $1 and %s = $2", r.JoinTable(), jcols[0], jcols[1]), jargs...).Scan(&ecnt)
		if ecnt > 0 {
			return nil
		}
		jsql := fmt.Sprintf("INSERT INTO %s (%s) VALUES ($1, $2)", jtable, strings.Join(jcols, ", "))
		fmt.Printf("[INSERT/JOIN] %s { %s }\n", jsql, logTrunc(jargs, 200))
		if !e.engine.dryRun {
			_ = e.tx.QueryRow(e.ctx, jsql, jargs...).Scan()
		}
	}
	return nil
}

func (r *Relationship) joinDelete(pk, fk any, q *Query) error {
	jc := fmt.Sprintf("%s_%s", r.Model.TableName, pascalToSnakeCase(r.FieldName))
	ds := fmt.Sprintf("DELETE FROM %s where %s = $1 and %s = $2",
		r.JoinTable(), jc, r.RelatedModel.TableName+"_id")
	fmt.Printf("[DELETE/JOIN] %s { %s }\n", ds, logTrunc([]any{pk, fk}, 200))
	if !q.engine.dryRun {
		_, err := q.tx.Exec(q.ctx, ds, pk, fk)
		return err
	}
	return nil
}

func parseRelationship(field reflect.StructField, modelMap map[string]*Model, outerType reflect.Type, idx int) *Relationship {
	rel := &Relationship{
		Model:        modelMap[outerType.Name()],
		RelatedModel: modelMap[field.Type.Name()],
		RelatedType:  field.Type,
		Idx:          idx,
		Kind:         field.Type.Kind(),
		FieldName:    field.Name,
	}
	if rel.RelatedType.Kind() == reflect.Slice || rel.RelatedType.Kind() == reflect.Array {
		rel.RelatedType = rel.RelatedType.Elem()
	}
	if rel.RelatedModel == nil {
		if rel.RelatedType.Name() == "" {
			rt := rel.RelatedType
			for rt.Kind() == reflect.Ptr || rt.Kind() == reflect.Slice || rt.Kind() == reflect.Array {
				rel.RelatedType = rel.RelatedType.Elem()
				rt = rel.RelatedType
			}
		}
		rel.RelatedModel = modelMap[rel.RelatedType.Name()]
		if _, ok := modelMap[rel.RelatedType.Name()]; !ok {
			rel.RelatedModel = parseModel(reflect.New(rel.RelatedType).Interface())
			modelMap[rel.RelatedType.Name()] = rel.RelatedModel
			parseModelFields(rel.RelatedModel, modelMap)
			rel.RelatedModel.embeddedIsh = true
		}
	}
	switch field.Type.Kind() {
	case reflect.Struct:
		rel.Type = HasOne
	case reflect.Slice:
		rel.Type = HasMany
	}
	return rel
}
func addForeignKeyFields(ref *Relationship) {
	rf := ref.RelatedModel.Fields[ref.RelatedModel.IDField]
	if rf != nil {
		if !ref.RelatedModel.embeddedIsh && !ref.Model.embeddedIsh {
			ff := ref.Model.Fields[ref.FieldName]
			ff.ColumnType = rf.ColumnType
			ff.ColumnName = pascalToSnakeCase(ref.JoinField())
			ff.isForeignKey = true
			ff.fk = ref
		} else if !ref.Model.embeddedIsh {
			sid := strings.TrimSuffix(ref.JoinField(), "ID")
			ref.RelatedModel.Relationships[sid] = &Relationship{
				FieldName:    sid,
				Type:         HasOne,
				RelatedModel: ref.Model,
				Model:        ref.RelatedModel,
				Kind:         ref.RelatedModel.Type.Kind(),
				Idx:          -1,
				RelatedType:  ref.Model.Type,
			}
			ref.RelatedModel.addField(&Field{
				ColumnType:   rf.ColumnType,
				ColumnName:   pascalToSnakeCase(ref.JoinField()),
				Name:         sid,
				isForeignKey: true,
				Type:         rf.Type,
				Index:        -1,
				fk:           ref.RelatedModel.Relationships[sid],
			})
		} else if ref.Model.embeddedIsh && !ref.RelatedModel.embeddedIsh {

		}
	} else {
		ref.RelatedModel.addField(&Field{
			Name:          "ID",
			ColumnName:    "id",
			ColumnType:    "bigserial",
			PrimaryKey:    true,
			Type:          ref.RelatedType,
			Index:         -1,
			AutoIncrement: true,
		})
		ff := ref.Model.Fields[ref.FieldName]
		ff.ColumnType = "bigint"
		ff.ColumnName = pascalToSnakeCase(ref.RelatedModel.Name + "ID")
		ff.isForeignKey = true
		ff.fk = ref
		ref.RelatedModel.IDField = "ID"
		/*
			nn := ref.Model.Name + "ID"
			ref.RelatedModel.Relationships[ref.Model.Name] = &Relationship{
				Type:         HasOne,
				RelatedModel: ref.Model,
				Model:        ref.RelatedModel,
				Idx:          65536,
				Kind:         ref.RelatedModel.Type.Kind(),
				RelatedType:  ref.RelatedModel.Type,
				FieldName:    nn,
			}
			ref.RelatedModel.addField(&Field{
				Name:         nn,
				Type:         ref.Model.Type,
				fk:           ref.RelatedModel.Relationships[nn],
				ColumnName:   pascalToSnakeCase(nn),
				Index:        -1,
				ColumnType:   ref.Model.Fields[ref.Model.IDField].ColumnType,
				isForeignKey: true,
			})*/

	}
}