Add support for omitempty in JSON tags

Adds a new configuration option json_tags_omit_empty

Author: abdullah2993

docs/reference/config.md

@@ -171,6 +171,8 @@ The `gen` mapping supports the following keys:
   - If true, "Id" in json tags will be uppercase. If false, will be camelcase. Defaults to `false`
 - `json_tags_case_style`:
   - `camel` for camelCase, `pascal` for PascalCase, `snake` for snake_case or `none` to use the column name in the DB. Defaults to `none`.
+- `json_tags_omit_empty`:
+  - If true will add `omitempty` to JSON tags. Defaults to `false`.
 - `omit_unused_structs`:
   - If `true`, sqlc won't generate table and enum structs that aren't used in queries for a given package. Defaults to `false`.
 - `output_batch_file_name`:

internal/codegen/golang/field.go

@@ -44,11 +44,14 @@ func TagsToString(tags map[string]string) string {
 func JSONTagName(name string, options *opts.Options) string {
 	style := options.JsonTagsCaseStyle
 	idUppercase := options.JsonTagsIdUppercase
-	if style == "" || style == "none" {
-		return name
-	} else {
-		return SetJSONCaseStyle(name, style, idUppercase)
+	addOmitEmpty := options.JsonTagsOmitEmpty
+	if style != "" && style != "none" {
+		name = SetJSONCaseStyle(name, style, idUppercase)
 	}
+	if addOmitEmpty {
+		name = name + ",omitempty"
+	}
+	return name
 }
 
 func SetCaseStyle(name string, style string) string {

internal/codegen/golang/opts/options.go

@@ -26,6 +26,7 @@ type Options struct {
 	EmitAllEnumValues           bool              `json:"emit_all_enum_values,omitempty" yaml:"emit_all_enum_values"`
 	EmitSqlAsComment            bool              `json:"emit_sql_as_comment,omitempty" yaml:"emit_sql_as_comment"`
 	JsonTagsCaseStyle           string            `json:"json_tags_case_style,omitempty" yaml:"json_tags_case_style"`
+	JsonTagsOmitEmpty           bool              `json:"json_tags_omit_empty,omitempty" yaml:"json_tags_omit_empty"`
 	Package                     string            `json:"package" yaml:"package"`
 	Out                         string            `json:"out" yaml:"out"`
 	Overrides                   []Override        `json:"overrides,omitempty" yaml:"overrides"`

internal/config/v_one.go

@@ -43,6 +43,7 @@ type v1PackageSettings struct {
 	EmitAllEnumValues         bool              `json:"emit_all_enum_values,omitempty" yaml:"emit_all_enum_values"`
 	EmitSqlAsComment          bool              `json:"emit_sql_as_comment,omitempty" yaml:"emit_sql_as_comment"`
 	JSONTagsCaseStyle         string            `json:"json_tags_case_style,omitempty" yaml:"json_tags_case_style"`
+	JSONTagsOmitEmpty         bool              `json:"json_tags_omit_empty,omitempty" yaml:"json_tags_omit_empty"`
 	SQLPackage                string            `json:"sql_package" yaml:"sql_package"`
 	SQLDriver                 string            `json:"sql_driver" yaml:"sql_driver"`
 	Overrides                 []golang.Override `json:"overrides" yaml:"overrides"`
@@ -158,6 +159,7 @@ func (c *V1GenerateSettings) Translate() Config {
 					SqlDriver:                 pkg.SQLDriver,
 					Overrides:                 pkg.Overrides,
 					JsonTagsCaseStyle:         pkg.JSONTagsCaseStyle,
+					JsonTagsOmitEmpty:         pkg.JSONTagsOmitEmpty,
 					OutputBatchFileName:       pkg.OutputBatchFileName,
 					OutputDbFileName:          pkg.OutputDBFileName,
 					OutputModelsFileName:      pkg.OutputModelsFileName,

internal/endtoend/testdata/json_tags/omit_empty/postgresql/pgx/v4/go/db.go

@@ -0,0 +1,2 @@
+-- name: GetAll :many
+SELECT * FROM users;

internal/endtoend/testdata/json_tags/omit_empty/postgresql/pgx/v4/go/models.go

@@ -0,0 +1,6 @@
+CREATE TABLE users (
+    first_name varchar(255),
+    last_name  varchar(255),
+    age        smallint
+);
+

internal/endtoend/testdata/json_tags/omit_empty/postgresql/pgx/v4/go/query.sql.go

@@ -0,0 +1,15 @@
+{
+  "version": "1",
+  "packages": [
+    {
+      "path": "go",
+      "engine": "postgresql",
+      "sql_package": "pgx/v4",
+      "name": "querytest",
+      "schema": "schema.sql",
+      "queries": "query.sql",
+      "emit_json_tags": true,
+      "json_tags_omit_empty": true
+    }
+  ]
+}