From 922a8efc53e0d93fbabc9b87d0d7b3b8d941ef70 Mon Sep 17 00:00:00 2001
From: Jinzhu <wosmvp@gmail.com>
Date: Tue, 19 May 2020 21:50:06 +0800
Subject: [PATCH] Generate Query Conds for Relationship

---
 association.go         | 29 ++++++++++++++++++++-------
 schema/relationship.go | 45 ++++++++++++++++++++++++++++++++++++++++++
 schema/schema.go       |  5 +++++
 3 files changed, 72 insertions(+), 7 deletions(-)

diff --git a/association.go b/association.go
index a9345255..82a2274e 100644
--- a/association.go
+++ b/association.go
@@ -3,6 +3,7 @@ package gorm
 import (
 	"fmt"
 
+	"github.com/jinzhu/gorm/clause"
 	"github.com/jinzhu/gorm/schema"
 )
 
@@ -31,10 +32,6 @@ func (db *DB) Association(column string) *Association {
 
 func (association *Association) Find(out interface{}, conds ...interface{}) error {
 	if association.Error == nil {
-		for _, ref := range association.Relationship.References {
-			if ref.OwnPrimaryKey {
-			}
-		}
 	}
 
 	return association.Error
@@ -53,9 +50,27 @@ func (association *Association) Delete(values ...interface{}) error {
 }
 
 func (association *Association) Clear() error {
-	return association.Error
+	return association.Replace()
 }
 
-func (association *Association) Count() int {
-	return 0
+func (association *Association) Count() (count int) {
+	if association.Error == nil {
+		var (
+			tx    = association.DB
+			conds = association.Relationship.ToQueryConditions(tx.Statement.ReflectValue)
+		)
+
+		if association.Relationship.JoinTable != nil {
+			tx.Clauses(clause.From{Joins: []clause.Join{{
+				Table: clause.Table{Name: association.Relationship.JoinTable.Table},
+				ON:    clause.Where{Exprs: conds},
+			}}})
+		} else {
+			tx.Clauses(clause.Where{Exprs: conds})
+		}
+
+		association.Error = tx.Count(&count).Error
+	}
+
+	return
 }
diff --git a/schema/relationship.go b/schema/relationship.go
index 4ffea8b3..59aaa7e4 100644
--- a/schema/relationship.go
+++ b/schema/relationship.go
@@ -6,6 +6,7 @@ import (
 	"regexp"
 	"strings"
 
+	"github.com/jinzhu/gorm/clause"
 	"github.com/jinzhu/inflection"
 )
 
@@ -345,3 +346,47 @@ func (rel *Relationship) ParseConstraint() *Constraint {
 
 	return &constraint
 }
+
+func (rel *Relationship) ToQueryConditions(reflectValue reflect.Value) (conds []clause.Expression) {
+	foreignFields := []*Field{}
+	relForeignKeys := []string{}
+
+	if rel.JoinTable != nil {
+		for _, ref := range rel.References {
+			if ref.OwnPrimaryKey {
+				foreignFields = append(foreignFields, ref.PrimaryKey)
+				relForeignKeys = append(relForeignKeys, ref.PrimaryKey.DBName)
+			} else if ref.PrimaryValue != "" {
+				conds = append(conds, clause.Eq{
+					Column: clause.Column{Table: rel.JoinTable.Table, Name: ref.ForeignKey.DBName},
+					Value:  ref.PrimaryValue,
+				})
+			} else {
+				conds = append(conds, clause.Eq{
+					Column: clause.Column{Table: rel.JoinTable.Table, Name: ref.ForeignKey.DBName},
+					Value:  clause.Column{Table: rel.FieldSchema.Table, Name: ref.PrimaryKey.DBName},
+				})
+			}
+		}
+	} else {
+		for _, ref := range rel.References {
+			if ref.OwnPrimaryKey {
+				relForeignKeys = append(relForeignKeys, ref.ForeignKey.DBName)
+				foreignFields = append(foreignFields, ref.PrimaryKey)
+			} else if ref.PrimaryValue != "" {
+				conds = append(conds, clause.Eq{
+					Column: clause.Column{Table: rel.FieldSchema.Table, Name: ref.ForeignKey.DBName},
+					Value:  ref.PrimaryValue,
+				})
+			} else {
+				relForeignKeys = append(relForeignKeys, ref.PrimaryKey.DBName)
+				foreignFields = append(foreignFields, ref.ForeignKey)
+			}
+		}
+	}
+
+	_, foreignValues := GetIdentityFieldValuesMap(reflectValue, foreignFields)
+	column, values := ToQueryValues(relForeignKeys, foreignValues)
+	conds = append(conds, clause.IN{Column: column, Values: values})
+	return
+}
diff --git a/schema/schema.go b/schema/schema.go
index 5a28797b..79faae12 100644
--- a/schema/schema.go
+++ b/schema/schema.go
@@ -8,6 +8,7 @@ import (
 	"reflect"
 	"sync"
 
+	"github.com/jinzhu/gorm/clause"
 	"github.com/jinzhu/gorm/logger"
 )
 
@@ -26,6 +27,10 @@ type Schema struct {
 	FieldsByDBName            map[string]*Field
 	FieldsWithDefaultDBValue  map[string]*Field // fields with default value assigned by database
 	Relationships             Relationships
+	CreateClauses             []clause.Interface
+	QueryClauses              []clause.Interface
+	UpdateClauses             []clause.Interface
+	DeleteClauses             []clause.Interface
 	BeforeCreate, AfterCreate bool
 	BeforeUpdate, AfterUpdate bool
 	BeforeDelete, AfterDelete bool