Add WhereHas and WhereDoesntHave helpers for relationship filtering

callbacks/query.go

@@ -57,6 +57,23 @@
 			}
 		}
 
+		if len(db.Statement.WhereHasConditions) > 0 {
+			for _, whereHasCondition := range db.Statement.WhereHasConditions {
+				cl, err := newWhereHas(db, whereHasCondition.IsDoesntHave, whereHasCondition.Relation, whereHasCondition.Conds, db.Statement.Schema)
+				if err != nil {
+					db.AddError(err)
+
+					continue
+				}
+
+				if cl == nil {
+					continue
+				}
+
+				db.Statement.AddClause(cl)
+			}
+		}
+
 		if len(db.Statement.Selects) > 0 {
 			clauseSelect.Columns = make([]clause.Column, len(db.Statement.Selects))
 			for idx, name := range db.Statement.Selects {

callbacks/where_has.go

@@ -0,0 +1,197 @@
+package callbacks
+
+import (
+	"fmt"
+
+	"gorm.io/gorm"
+	"gorm.io/gorm/clause"
+	"gorm.io/gorm/schema"
+)
+
+func whereHasDb(db *gorm.DB) *gorm.DB {
+	tx := db.Session(&gorm.Session{Context: db.Statement.Context, NewDB: true, SkipHooks: db.Statement.SkipHooks, Initialized: true})
+
+	return tx
+}
+
+func newWhereHas(db *gorm.DB, isDoesntHave bool, relationName string, conds []interface{}, s *schema.Schema) (*clause.Where, error) {
+	var err error
+
+	rel, ok := s.Relationships.Relations[relationName]
+	if !ok {
+		return nil, fmt.Errorf("relation %s not found", relationName)
+	}
+
+	tx := whereHasDb(db)
+
+	reflectResults := rel.FieldSchema.MakeSlice().Elem()
+
+	tx = tx.Model(reflectResults.Addr().Interface()).Select("id")
+	if err = tx.Statement.Parse(tx.Statement.Model); err != nil {
+		return nil, err
+	}
+
+	if rel.Type == schema.Many2Many {
+		tx, err = existsMany2many(db, tx, rel, conds)
+		if err != nil {
+			return nil, err
+		}
+	} else if rel.Type == schema.BelongsTo {
+		tx, err = existsBelongsTo(db, tx, rel, conds)
+		if err != nil {
+			return nil, err
+		}
+	} else if rel.Type == schema.HasMany {
+		tx, err = existsHasMany(db, tx, rel, conds)
+		if err != nil {
+			return nil, err
+		}
+	} else if rel.Type == schema.HasOne {
+		tx, err = existsHasOne(db, tx, rel, conds)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	cond := "EXISTS(?)"
+	if isDoesntHave {
+		cond = "NOT " + cond
+	}
+
+	cl := clause.Where{
+		Exprs: []clause.Expression{
+			clause.Expr{
+				SQL:                cond,
+				Vars:               []interface{}{tx},
+				WithoutParentheses: false,
+			},
+		},
+	}
+
+	return &cl, nil
+}
+
+func existsHasOne(mainQuery *gorm.DB, existsQuery *gorm.DB, rel *schema.Relationship, conds []interface{}) (*gorm.DB, error) {
+	return existsHasMany(mainQuery, existsQuery, rel, conds)
+}
+
+func existsHasMany(mainQuery *gorm.DB, existsQuery *gorm.DB, rel *schema.Relationship, conds []interface{}) (*gorm.DB, error) {
+	for _, reference := range rel.References {
+		if reference.PrimaryKey != nil {
+			existsQuery.Statement.AddClause(clause.Where{
+				Exprs: []clause.Expression{
+					clause.Eq{
+						Column: clause.Column{Table: existsQuery.Statement.Table, Name: reference.ForeignKey.DBName},
+						Value:  clause.Column{Table: mainQuery.Statement.Table, Name: reference.PrimaryKey.DBName},
+					},
+				},
+			})
+		} else {
+			existsQuery.Statement.AddClause(clause.Where{
+				Exprs: []clause.Expression{
+					clause.Eq{
+						Column: clause.Column{Table: existsQuery.Statement.Table, Name: reference.ForeignKey.DBName},
+						Value:  reference.PrimaryValue,
+					},
+				},
+			})
+		}
+	}
+
+	existsQuery = applyConds(existsQuery, conds)
+
+	return existsQuery, nil
+}
+
+func existsBelongsTo(mainQuery *gorm.DB, existsQuery *gorm.DB, rel *schema.Relationship, conds []interface{}) (*gorm.DB, error) {
+	for _, reference := range rel.References {
+		existsQuery.Statement.AddClause(clause.Where{
+			Exprs: []clause.Expression{
+				clause.Eq{
+					Column: clause.Column{Table: existsQuery.Statement.Table, Name: reference.PrimaryKey.DBName},
+					Value:  clause.Column{Table: mainQuery.Statement.Table, Name: reference.ForeignKey.DBName},
+				},
+			},
+		})
+	}
+
+	existsQuery = applyConds(existsQuery, conds)
+
+	return existsQuery, nil
+}
+
+func existsMany2many(mainQuery *gorm.DB, existsQuery *gorm.DB, rel *schema.Relationship, conds []interface{}) (*gorm.DB, error) {
+	if rel.JoinTable != nil {
+		var parentTableField *schema.Reference = nil
+		var primaryTableField *schema.Reference = nil
+
+		for _, reference := range rel.References {
+			if !reference.OwnPrimaryKey {
+				parentTableField = reference
+			} else {
+				primaryTableField = reference
+			}
+		}
+
+		if parentTableField == nil {
+			return nil, fmt.Errorf("relation %s has no parent table field", rel.Name)
+		}
+
+		if primaryTableField == nil {
+			return nil, fmt.Errorf("relation %s has no primary table field", rel.Name)
+		}
+
+		fromClause := clause.From{
+			Tables: nil,
+			Joins: []clause.Join{
+				{
+					Type:  clause.InnerJoin,
+					Table: clause.Table{Name: rel.JoinTable.Table},
+					ON: clause.Where{
+						Exprs: []clause.Expression{
+							clause.Eq{
+								Column: clause.Column{Table: rel.JoinTable.Table, Name: parentTableField.ForeignKey.DBName},
+								Value:  clause.Column{Table: existsQuery.Statement.Table, Name: parentTableField.PrimaryKey.DBName},
+							},
+						},
+					},
+				},
+			},
+		}
+
+		existsQuery.Statement.AddClause(fromClause)
+
+		existsQuery.Statement.AddClause(clause.Where{
+			Exprs: []clause.Expression{
+				clause.Eq{
+					Column: clause.Column{Table: rel.JoinTable.Table, Name: primaryTableField.ForeignKey.DBName},
+					Value:  clause.Column{Table: mainQuery.Statement.Table, Name: primaryTableField.PrimaryKey.DBName},
+				},
+			},
+		})
+
+		existsQuery = applyConds(existsQuery, conds)
+	}
+
+	return existsQuery, nil
+}
+
+func applyConds(existsQuery *gorm.DB, conds []interface{}) *gorm.DB {
+	inlineConds := make([]interface{}, 0)
+
+	for _, cond := range conds {
+		if fc, ok := cond.(func(*gorm.DB) *gorm.DB); ok {
+			existsQuery = fc(existsQuery)
+		} else {
+			inlineConds = append(inlineConds, cond)
+		}
+	}
+
+	if len(inlineConds) > 0 {
+		existsQuery = existsQuery.Where(inlineConds[0], inlineConds[1:]...)
+	}
+
+	existsQuery.WhereHas("Some")
+
+	return existsQuery
+}

chainable_api.go

@@ -212,6 +212,38 @@ func (db *DB) Where(query interface{}, args ...interface{}) (tx *DB) {
 	return
 }
 
+func (db *DB) WhereHas(relation string, args ...interface{}) (tx *DB) {
+	tx = db.getInstance()
+
+	if tx.Statement.WhereHasConditions == nil {
+		tx.Statement.WhereHasConditions = make([]whereHasCondition, 0)
+	}
+
+	tx.Statement.WhereHasConditions = append(tx.Statement.WhereHasConditions, whereHasCondition{
+		IsDoesntHave: false,
+		Relation:     relation,
+		Conds:        args,
+	})
+
+	return
+}
+
+func (db *DB) WhereDoesntHave(relation string, args ...interface{}) (tx *DB) {
+	tx = db.getInstance()
+
+	if tx.Statement.WhereHasConditions == nil {
+		tx.Statement.WhereHasConditions = make([]whereHasCondition, 0)
+	}
+
+	tx.Statement.WhereHasConditions = append(tx.Statement.WhereHasConditions, whereHasCondition{
+		IsDoesntHave: true,
+		Relation:     relation,
+		Conds:        args,
+	})
+
+	return
+}
+
 // Not add NOT conditions
 //
 // Not works similarly to where, and has the same syntax.

statement.go

@@ -35,6 +35,7 @@
 	ColumnMapping        map[string]string // map columns
 	Joins                []join
 	Preloads             map[string][]interface{}
+	WhereHasConditions   []whereHasCondition
 	Settings             sync.Map
 	ConnPool             ConnPool
 	Schema               *schema.Schema
@@ -50,6 +51,12 @@
 	Result               *result
 }
 
+type whereHasCondition struct {
+	IsDoesntHave bool
+	Relation     string
+	Conds        []interface{}
+}
+
 type join struct {
 	Name       string
 	Alias      string
@@ -355,6 +362,8 @@
 					conds = append(conds, cs.Expression)
 				}
 			}
+
+			stmt.WhereHasConditions = append(stmt.WhereHasConditions, v.Statement.WhereHasConditions...)
 		case map[interface{}]interface{}:
 			for i, j := range v {
 				conds = append(conds, clause.Eq{Column: i, Value: j})
@@ -540,6 +549,7 @@
 		Omits:                stmt.Omits,
 		ColumnMapping:        stmt.ColumnMapping,
 		Preloads:             map[string][]interface{}{},
+		WhereHasConditions:   []whereHasCondition{},
 		ConnPool:             stmt.ConnPool,
 		Schema:               stmt.Schema,
 		Context:              stmt.Context,
@@ -562,6 +572,10 @@
 		newStmt.Preloads[k] = p
 	}
 
+	for _, condition := range stmt.WhereHasConditions {
+		newStmt.WhereHasConditions = append(newStmt.WhereHasConditions, condition)
+	}
+
 	if len(stmt.Joins) > 0 {
 		newStmt.Joins = make([]join, len(stmt.Joins))
 		copy(newStmt.Joins, stmt.Joins)