From 142c46228b7509e6350b4554b05af468a9594411 Mon Sep 17 00:00:00 2001
From: MarkJoyMa <markjoyma@163.com>
Date: Thu, 2 Mar 2023 21:47:07 +0800
Subject: [PATCH] x

---
 core/conf/config.go              |  3 ++-
 core/conf/config_test.go         | 12 ++++++++++++
 core/mapping/unmarshaler.go      |  9 ++++++++-
 core/mapping/unmarshaler_test.go | 12 ++++++++++++
 4 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/core/conf/config.go b/core/conf/config.go
index 170c6c14..d53a79d6 100644
--- a/core/conf/config.go
+++ b/core/conf/config.go
@@ -32,7 +32,8 @@ type fieldInfo struct {
 	mapField *fieldInfo
 }
 
-// FillDefault fills the default values for the given v.
+// FillDefault fills the default values for the given v,
+// and the premise is that the value of v must be guaranteed to be empty
 func FillDefault(v any) error {
 	return fillDefaultUnmarshaler.Unmarshal(map[string]any{}, v)
 }
diff --git a/core/conf/config_test.go b/core/conf/config_test.go
index 33785db5..8dba474f 100644
--- a/core/conf/config_test.go
+++ b/core/conf/config_test.go
@@ -1078,4 +1078,16 @@ func TestFillDefaultUnmarshal(t *testing.T) {
 		assert.Equal(t, st.A, "a")
 		assert.Equal(t, st.C, "c")
 	})
+
+	t.Run("has vaue", func(t *testing.T) {
+		type St struct {
+			A string `json:",default=a"`
+			B string
+		}
+		var st = St{
+			A: "b",
+		}
+		err := FillDefault(&st)
+		assert.Error(t, err)
+	})
 }
diff --git a/core/mapping/unmarshaler.go b/core/mapping/unmarshaler.go
index 5f3061d2..fe638ce1 100644
--- a/core/mapping/unmarshaler.go
+++ b/core/mapping/unmarshaler.go
@@ -711,7 +711,14 @@ func (u *Unmarshaler) processNamedField(field reflect.StructField, value reflect
 
 	valuer := createValuer(m, opts)
 	mapValue, hasValue := getValue(valuer, canonicalKey)
-	if !hasValue || u.opts.fillDefault {
+
+	// When fillDefault is used, m is a null value, hasValue must be false, all priority judgments fillDefault,
+	if u.opts.fillDefault {
+		if !value.IsZero() {
+			return fmt.Errorf("set the default value, %s must be zero", fullName)
+		}
+		return u.processNamedFieldWithoutValue(field.Type, value, opts, fullName)
+	} else if !hasValue {
 		return u.processNamedFieldWithoutValue(field.Type, value, opts, fullName)
 	}
 
diff --git a/core/mapping/unmarshaler_test.go b/core/mapping/unmarshaler_test.go
index 0c50d269..d2e6fc09 100644
--- a/core/mapping/unmarshaler_test.go
+++ b/core/mapping/unmarshaler_test.go
@@ -4425,4 +4425,16 @@ func TestFillDefaultUnmarshal(t *testing.T) {
 		assert.Equal(t, st.A, "a")
 		assert.Equal(t, st.C, "c")
 	})
+
+	t.Run("has value", func(t *testing.T) {
+		type St struct {
+			A string `json:",default=a"`
+			B string
+		}
+		var st = St{
+			A: "b",
+		}
+		err := fillDefaultUnmarshal.Unmarshal(map[string]any{}, &st)
+		assert.Error(t, err)
+	})
 }