forked from mirror/gorm
290 lines
8.9 KiB
Go
290 lines
8.9 KiB
Go
package schema
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import (
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"fmt"
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"reflect"
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"strings"
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)
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// RelationshipType relationship type
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type RelationshipType string
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const (
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HasOne RelationshipType = "has_one" // HasOneRel has one relationship
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HasMany RelationshipType = "has_many" // HasManyRel has many relationship
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BelongsTo RelationshipType = "belongs_to" // BelongsToRel belongs to relationship
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Many2Many RelationshipType = "many_to_many" // Many2ManyRel many to many relationship
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)
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type Relationships struct {
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HasOne []*Relationship
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BelongsTo []*Relationship
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HasMany []*Relationship
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Many2Many []*Relationship
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Relations map[string]*Relationship
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}
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type Relationship struct {
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Name string
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Type RelationshipType
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Field *Field
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Polymorphic *Polymorphic
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References []Reference
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Schema *Schema
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FieldSchema *Schema
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JoinTable *Schema
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foreignKeys, primaryKeys []string
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}
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type Polymorphic struct {
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PolymorphicID *Field
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PolymorphicType *Field
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Value string
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}
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type Reference struct {
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PriamryKey *Field
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PriamryValue string
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ForeignKey *Field
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OwnPriamryKey bool
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}
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func (schema *Schema) parseRelation(field *Field) {
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var (
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err error
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fieldValue = reflect.New(field.FieldType).Interface()
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relation = &Relationship{
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Name: field.Name,
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Field: field,
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Schema: schema,
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foreignKeys: toColumns(field.TagSettings["FOREIGNKEY"]),
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primaryKeys: toColumns(field.TagSettings["REFERENCES"]),
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}
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)
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if relation.FieldSchema, err = Parse(fieldValue, schema.cacheStore, schema.namer); err != nil {
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schema.err = err
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return
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}
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if polymorphic, _ := field.TagSettings["POLYMORPHIC"]; polymorphic != "" {
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schema.buildPolymorphicRelation(relation, field, polymorphic)
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} else if many2many, _ := field.TagSettings["MANY2MANY"]; many2many != "" {
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schema.buildMany2ManyRelation(relation, field, many2many)
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} else {
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switch field.FieldType.Kind() {
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case reflect.Struct, reflect.Slice:
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schema.guessRelation(relation, field, true)
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default:
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schema.err = fmt.Errorf("unsupported data type %v for %v on field %v", relation.FieldSchema, schema, field.Name)
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}
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}
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if relation.Type == "has" {
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switch field.FieldType.Kind() {
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case reflect.Struct:
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relation.Type = HasOne
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case reflect.Slice:
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relation.Type = HasMany
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}
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}
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if schema.err == nil {
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schema.Relationships.Relations[relation.Name] = relation
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switch relation.Type {
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case HasOne:
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schema.Relationships.HasOne = append(schema.Relationships.HasOne, relation)
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case HasMany:
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schema.Relationships.HasMany = append(schema.Relationships.HasMany, relation)
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case BelongsTo:
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schema.Relationships.BelongsTo = append(schema.Relationships.BelongsTo, relation)
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case Many2Many:
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schema.Relationships.Many2Many = append(schema.Relationships.Many2Many, relation)
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}
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}
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}
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// User has many Toys, its `Polymorphic` is `Owner`, Pet has one Toy, its `Polymorphic` is `Owner`
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// type User struct {
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// Toys []Toy `gorm:"polymorphic:Owner;"`
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// }
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// type Pet struct {
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// Toy Toy `gorm:"polymorphic:Owner;"`
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// }
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// type Toy struct {
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// OwnerID int
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// OwnerType string
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// }
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func (schema *Schema) buildPolymorphicRelation(relation *Relationship, field *Field, polymorphic string) {
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relation.Polymorphic = &Polymorphic{
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Value: schema.Table,
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PolymorphicType: relation.FieldSchema.FieldsByName[polymorphic+"Type"],
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PolymorphicID: relation.FieldSchema.FieldsByName[polymorphic+"ID"],
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}
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if value, ok := field.TagSettings["POLYMORPHIC_VALUE"]; ok {
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relation.Polymorphic.Value = strings.TrimSpace(value)
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}
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if relation.Polymorphic.PolymorphicType == nil {
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schema.err = fmt.Errorf("invalid polymorphic type %v for %v on field %v, missing field %v", relation.FieldSchema, schema, field.Name, polymorphic+"Type")
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}
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if relation.Polymorphic.PolymorphicID == nil {
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schema.err = fmt.Errorf("invalid polymorphic type %v for %v on field %v, missing field %v", relation.FieldSchema, schema, field.Name, polymorphic+"ID")
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}
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if schema.err == nil {
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relation.References = append(relation.References, Reference{
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PriamryValue: relation.Polymorphic.Value,
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ForeignKey: relation.Polymorphic.PolymorphicType,
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})
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primaryKeyField := schema.PrioritizedPrimaryField
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if len(relation.foreignKeys) > 0 {
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if primaryKeyField = schema.LookUpField(relation.foreignKeys[0]); primaryKeyField == nil || len(relation.foreignKeys) > 1 {
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schema.err = fmt.Errorf("invalid polymorphic foreign keys %+v for %v on field %v", relation.foreignKeys, schema, field.Name)
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}
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}
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relation.References = append(relation.References, Reference{
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PriamryKey: primaryKeyField,
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ForeignKey: relation.Polymorphic.PolymorphicType,
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OwnPriamryKey: true,
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})
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}
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relation.Type = "has"
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}
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func (schema *Schema) buildMany2ManyRelation(relation *Relationship, field *Field, many2many string) {
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relation.Type = Many2Many
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var (
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err error
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joinTableFields []reflect.StructField
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fieldsMap = map[string]*Field{}
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)
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for _, s := range []*Schema{schema, relation.Schema} {
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for _, primaryField := range s.PrimaryFields {
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fieldName := s.Name + primaryField.Name
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if _, ok := fieldsMap[fieldName]; ok {
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if field.Name != s.Name {
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fieldName = field.Name + primaryField.Name
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} else {
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fieldName = s.Name + primaryField.Name + "Reference"
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}
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}
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fieldsMap[fieldName] = primaryField
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joinTableFields = append(joinTableFields, reflect.StructField{
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Name: fieldName,
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PkgPath: primaryField.StructField.PkgPath,
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Type: primaryField.StructField.Type,
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Tag: removeSettingFromTag(primaryField.StructField.Tag, "column"),
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})
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}
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}
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if relation.JoinTable, err = Parse(reflect.New(reflect.StructOf(joinTableFields)).Interface(), schema.cacheStore, schema.namer); err != nil {
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schema.err = err
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}
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relation.JoinTable.Name = many2many
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relation.JoinTable.Table = schema.namer.JoinTableName(many2many)
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// build references
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for _, f := range relation.JoinTable.Fields {
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relation.References = append(relation.References, Reference{
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PriamryKey: fieldsMap[f.Name],
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ForeignKey: f,
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OwnPriamryKey: schema == fieldsMap[f.Name].Schema,
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})
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}
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return
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}
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func (schema *Schema) guessRelation(relation *Relationship, field *Field, guessHas bool) {
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var (
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primaryFields, foreignFields []*Field
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primarySchema, foreignSchema = schema, relation.FieldSchema
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)
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if !guessHas {
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primarySchema, foreignSchema = relation.FieldSchema, schema
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}
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reguessOrErr := func(err string, args ...interface{}) {
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if guessHas {
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schema.guessRelation(relation, field, false)
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} else {
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schema.err = fmt.Errorf(err, args...)
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}
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}
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if len(relation.foreignKeys) > 0 {
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for _, foreignKey := range relation.foreignKeys {
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if f := foreignSchema.LookUpField(foreignKey); f != nil {
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foreignFields = append(foreignFields, f)
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} else {
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reguessOrErr("unsupported relations %v for %v on field %v with foreign keys %v", relation.FieldSchema, schema, field.Name, relation.foreignKeys)
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return
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}
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}
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} else {
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for _, primaryField := range primarySchema.PrimaryFields {
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lookUpName := schema.Name + primaryField.Name
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if !guessHas {
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lookUpName = field.Name + primaryField.Name
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}
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if f := foreignSchema.LookUpField(lookUpName); f != nil {
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foreignFields = append(foreignFields, f)
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primaryFields = append(primaryFields, primaryField)
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}
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}
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}
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if len(foreignFields) == 0 {
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reguessOrErr("failed to guess %v's relations with %v's field %v 1 g %v", relation.FieldSchema, schema, field.Name, guessHas)
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return
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} else if len(relation.primaryKeys) > 0 {
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for idx, primaryKey := range relation.primaryKeys {
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if f := primarySchema.LookUpField(primaryKey); f != nil {
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if len(primaryFields) < idx+1 {
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primaryFields = append(primaryFields, f)
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} else if f != primaryFields[idx] {
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reguessOrErr("unsupported relations %v for %v on field %v with primary keys %v", relation.FieldSchema, schema, field.Name, relation.primaryKeys)
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return
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}
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} else {
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reguessOrErr("unsupported relations %v for %v on field %v with primary keys %v", relation.FieldSchema, schema, field.Name, relation.primaryKeys)
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return
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}
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}
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} else if len(primaryFields) == 0 {
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if len(foreignFields) == 1 {
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primaryFields = append(primaryFields, primarySchema.PrioritizedPrimaryField)
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} else if len(primarySchema.PrimaryFields) == len(foreignFields) {
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primaryFields = append(primaryFields, primarySchema.PrimaryFields...)
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} else {
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reguessOrErr("unsupported relations %v for %v on field %v", relation.FieldSchema, schema, field.Name)
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return
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}
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}
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// build references
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for idx, foreignField := range foreignFields {
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relation.References = append(relation.References, Reference{
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PriamryKey: primaryFields[idx],
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ForeignKey: foreignField,
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OwnPriamryKey: schema == primarySchema,
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})
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}
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if guessHas {
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relation.Type = "has"
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} else {
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relation.Type = BelongsTo
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}
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}
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