From 95b0ddded3ec76b58c3281db2fce4945d073ec00 Mon Sep 17 00:00:00 2001
From: Saeid Aghapour <saeid.aghapour@snapp.cab>
Date: Sun, 9 Jul 2023 16:32:15 +0330
Subject: [PATCH] implement Hash method HMGet (#136)

---
 structure/hash.go      | 59 ++++++++++++++++++++++++++++++++++++++++++
 structure/hash_test.go | 27 +++++++++++++++++++
 2 files changed, 86 insertions(+)

diff --git a/structure/hash.go b/structure/hash.go
index 47c8cc1d..8cb7b8cf 100644
--- a/structure/hash.go
+++ b/structure/hash.go
@@ -220,6 +220,65 @@ func (hs *HashStructure) HGet(k string, f interface{}) (interface{}, error) {
 	return valueToInterface, nil
 }
 
+// HMGet gets the string value of a hash field.
+func (hs *HashStructure) HMGet(k string, f ...interface{}) ([]interface{}, error) {
+	// Convert the parameters to bytes
+	key := stringToBytesWithKey(k)
+	var interfaces []interface{}
+
+	for _, fi := range f {
+		// Convert the parameters to bytes
+		field, err, _ := interfaceToBytes(fi)
+		if err != nil {
+			return nil, err
+		}
+
+		// Check the parameters
+		if len(key) == 0 || len(field) == 0 {
+			return nil, _const.ErrKeyIsEmpty
+		}
+
+		// Find the hash metadata by the given key
+		hashMeta, err := hs.findHashMeta(k, Hash)
+		if err != nil {
+			return nil, err
+		}
+
+		// If the counter is 0, return nil
+		if hashMeta.counter == 0 {
+			return nil, nil
+		}
+
+		// Create a new HashField
+		hf := &HashField{
+			field:   field,
+			key:     key,
+			version: hashMeta.version,
+		}
+
+		// Encode the HashField
+		hfBuf := hf.encodeHashField()
+
+		// Get the field from the database
+		value, err := hs.db.Get(hfBuf)
+		if err != nil {
+			return nil, err
+		}
+
+		// Get the value type from the hashValueTypes
+		valueType := hs.hashValueType
+
+		// Values of different types need to be converted to corresponding types
+		valueToInterface, err := byteToInterface(value, valueType)
+		if err != nil {
+			return nil, err
+		}
+		interfaces = append(interfaces, valueToInterface)
+	}
+
+	return interfaces, nil
+}
+
 // HDel deletes one field from a hash.
 func (hs *HashStructure) HDel(k string, f interface{}) (bool, error) {
 	// Convert the parameters to bytes
diff --git a/structure/hash_test.go b/structure/hash_test.go
index f36a4a05..a08f9cff 100644
--- a/structure/hash_test.go
+++ b/structure/hash_test.go
@@ -47,6 +47,33 @@ func TestHashStructure_HGet(t *testing.T) {
 
 }
 
+func TestHashStructure_HMGet(t *testing.T) {
+	hash := initHashDB()
+	defer hash.db.Close()
+
+	ok1, err := hash.HSet("1", []byte("field1"), randkv.RandomValue(10))
+	assert.Nil(t, err)
+	assert.True(t, ok1)
+
+	v1 := randkv.RandomValue(10)
+	ok2, err := hash.HSet("1", []byte("field1"), v1)
+	assert.Nil(t, err)
+	assert.False(t, ok2)
+
+	v2 := randkv.RandomValue(10)
+	ok3, err := hash.HSet("1", []byte("field2"), v2)
+	assert.Nil(t, err)
+	assert.True(t, ok3)
+
+	mulVal, err := hash.HMGet("1", []byte("field1"), []byte("field2"))
+	assert.Equal(t, v1, mulVal[0])
+	assert.Equal(t, v2, mulVal[1])
+
+	_, err = hash.HGet("1", []byte("field3"))
+	assert.Equal(t, err, _const.ErrKeyNotFound)
+
+}
+
 func TestHashStructure_HDel(t *testing.T) {
 	hash := initHashDB()
 	defer hash.db.Close()