entc/schema: adding support for immutable fields (#1340)

Summary:
Pull Request resolved: https://github.com/facebookexternal/fbc/pull/1340

Immutable fields are ent fields which cannot be updated

Reviewed By: a8m

Differential Revision: D16899625

fbshipit-source-id: ca482c66570e84ca9a1e0a03f729847561f2816b

schema/field/field.go

@@ -117,6 +117,7 @@ type Field struct {
 	unique     bool
 	nillable   bool
 	optional   bool
+	immutable  bool
 	value      interface{}
 	validators []interface{}
 }
@@ -176,6 +177,9 @@ func (f Field) IsNillable() bool { return f.nillable }
 // IsOptional returns is this field is an optional field.
 func (f Field) IsOptional() bool { return f.optional }
 
+// IsImmutable returns is this field is an immutable field.
+func (f Field) IsImmutable() bool { return f.immutable }
+
 // IsUnique returns is this field is a unique field.
 func (f Field) IsUnique() bool { return f.unique }
 
@@ -264,6 +268,12 @@ func (b *intBuilder) Optional() *intBuilder {
 	return b
 }
 
+// Immutable indicates that this field cannot be updated.
+func (b *intBuilder) Immutable() *intBuilder {
+	b.immutable = true
+	return b
+}
+
 // StructTag sets the struct tag of the field.
 func (b *intBuilder) StructTag(s string) *intBuilder {
 	b.tag = s
@@ -355,6 +365,12 @@ func (b *floatBuilder) Optional() *floatBuilder {
 	return b
 }
 
+// Immutable indicates that this field cannot be updated.
+func (b *floatBuilder) Immutable() *floatBuilder {
+	b.immutable = true
+	return b
+}
+
 // StructTag sets the struct tag of the field.
 func (b *floatBuilder) StructTag(s string) *floatBuilder {
 	b.tag = s
@@ -440,6 +456,12 @@ func (b *stringBuilder) Optional() *stringBuilder {
 	return b
 }
 
+// Immutable indicates that this field cannot be updated.
+func (b *stringBuilder) Immutable() *stringBuilder {
+	b.immutable = true
+	return b
+}
+
 // Comment sets the comment of the field.
 func (b *stringBuilder) Comment(c string) *stringBuilder {
 	return b
@@ -484,6 +506,12 @@ func (b *timeBuilder) Optional() *timeBuilder {
 	return b
 }
 
+// Immutable indicates that this field cannot be updated.
+func (b *timeBuilder) Immutable() *timeBuilder {
+	b.immutable = true
+	return b
+}
+
 // Comment sets the comment of the field.
 func (b *timeBuilder) Comment(c string) *timeBuilder {
 	return b
@@ -531,6 +559,12 @@ func (b *boolBuilder) Optional() *boolBuilder {
 	return b
 }
 
+// Immutable indicates that this field cannot be updated.
+func (b *boolBuilder) Immutable() *boolBuilder {
+	b.immutable = true
+	return b
+}
+
 // Comment sets the comment of the field.
 func (b *boolBuilder) Comment(c string) *boolBuilder {
 	return b
@@ -567,6 +601,12 @@ func (b *bytesBuilder) Optional() *bytesBuilder {
 	return b
 }
 
+// Immutable indicates that this field cannot be updated.
+func (b *bytesBuilder) Immutable() *bytesBuilder {
+	b.immutable = true
+	return b
+}
+
 // Comment sets the comment of the field.
 func (b *bytesBuilder) Comment(c string) *bytesBuilder {
 	return b

schema/field/field_test.go

@@ -25,6 +25,7 @@ func TestInt(t *testing.T) {
 	f = field.Int("age").Range(20, 40).Nillable()
 	assert.False(t, f.HasDefault())
 	assert.True(t, f.IsNillable())
+	assert.False(t, f.IsImmutable())
 	assert.Len(t, f.Validators(), 1)
 
 	assert.Equal(t, field.TypeInt8, field.Int8("age").Type())
@@ -44,10 +45,11 @@ func TestFloat(t *testing.T) {
 }
 
 func TestBool(t *testing.T) {
-	f := field.Bool("active").Default(true)
+	f := field.Bool("active").Default(true).Immutable()
 	assert.Equal(t, "active", f.Name())
 	assert.Equal(t, field.TypeBool, f.Type())
 	assert.True(t, f.HasDefault())
+	assert.True(t, f.IsImmutable())
 	assert.Equal(t, true, f.Value())
 }