bool issue

[mybigman]

type Foo struct {
	A string
	B int64
	C bool
	D string
}

src := Foo{
	A: "a",
	B: 52,
	C: false,
	D: "2012-02-02",
}

dest := Foo{
	A: "b",
	B: 12,
	C: true,
	D: "2012-02-03",
}

mergo.Merge(&dest, src, mergo.WithOverride)
fmt.Println(src)
fmt.Println(dest)
fmt.Printf("%+v", dest)

got

{a 52 false 2012-02-02}
{a 52 true 2012-02-02}
{A:a B:52 C:true D:2012-02-02}

expected

{a 52 false 2012-02-02}
{a 52 false 2012-02-02}
{A:a B:52 C:false D:2012-02-02}

type Foo struct {
	A string
	B int64
	C bool
	D string
}

src := Foo{
	A: "a",
	B: 52,
	C: true,
	D: "2012-02-02",
}

dest := Foo{
	A: "b",
	B: 12,
	C: false,
	D: "2012-02-03",
}

mergo.Merge(&dest, src, mergo.WithOverride)
fmt.Println(src)
fmt.Println(dest)
fmt.Printf("%+v", dest)

got

{a 52 true 2012-02-02}
{a 52 true 2012-02-02}
{A:a B:52 C:true D:2012-02-02}

expected

{a 52 true 2012-02-02}
{a 52 true 2012-02-02}
{A:a B:52 C:true D:2012-02-02}

As you can see overriding true with false fails, however overriding false with true works

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[esperoz]

Stuck with the same issue. Fixed with mergo.WithoutDereference and pointer to bool in structure

[w570955342]

You can try using mergo.WithOverwriteWithEmptyValue instead of mergo.WithOverride.

[cgetzen]

For anyone having encountering this bug from helm (or sprig), you can use mergeOverwrite or mustMergeOverwrite and reverse the list of merged maps to achieve the correct behavior.

[lzap]

The zero values in Go are:

• 0 for numeric types,
• false for the boolean type, and
• "" (the empty string) for strings.

There is no way for the mergo library to detect when a value of primitive type was unset or explicitly set to zero value. Therefore there cannot be any merging strategy that will solve the mentioned bool problem. One possible solution to this is to use pointers as stated above.