Adding LastInsertId for Go

docs/reference/query-annotations.md

@@ -59,6 +59,24 @@ func (q *Queries) DeleteAllAuthors(ctx context.Context) (int64, error) {
 }
 ```
 
+## `:execlastid`
+
+The generated method will return the number generated by the database from the
+[result](https://golang.org/pkg/database/sql/#Result) returned by
+[ExecContext](https://golang.org/pkg/database/sql/#DB.ExecContext).
+
+```sql
+-- name: InsertAuthor :execlastid
+INSERT INTO authors (name) VALUES (?);
+```
+
+```go
+func (q *Queries) InsertAuthor(ctx context.Context, name string) (int64, error) {
+	_, err := q.db.ExecContext(ctx, insertAuthor, name)
+	// ...
+}
+```
+
 ## `:many`
 
 The generated method will return a slice of records via

internal/codegen/golang/templates/stdlib/interfaceCode.tmpl

@@ -38,6 +38,15 @@
             {{end -}}
             {{.MethodName}}(ctx context.Context, {{.Arg.Pair}}) (int64, error)
         {{- end}}
+        {{- if and (eq .Cmd ":execlastid") ($dbtxParam) }}
+            {{range .Comments}}//{{.}}
+            {{end -}}
+            {{.MethodName}}(ctx context.Context, db DBTX, {{.Arg.Pair}}) (int64, error)
+        {{- else if eq .Cmd ":execlastid"}}
+            {{range .Comments}}//{{.}}
+            {{end -}}
+            {{.MethodName}}(ctx context.Context, {{.Arg.Pair}}) (int64, error)
+        {{- end}}
         {{- if and (eq .Cmd ":execresult") ($dbtxParam) }}
             {{range .Comments}}//{{.}}
             {{end -}}

internal/codegen/golang/templates/stdlib/queryCode.tmpl

@@ -124,6 +124,28 @@ func (q *Queries) {{.MethodName}}(ctx context.Context, {{.Arg.Pair}}) (int64, er
 }
 {{end}}
 
+{{if eq .Cmd ":execlastid"}}
+{{range .Comments}}//{{.}}
+{{end -}}
+{{- if $.EmitMethodsWithDBArgument -}}
+func (q *Queries) {{.MethodName}}(ctx context.Context, db DBTX, {{.Arg.Pair}}) (int64, error) {
+{{- else -}}
+func (q *Queries) {{.MethodName}}(ctx context.Context, {{.Arg.Pair}}) (int64, error) {
+{{- end -}}
+    {{- if $.EmitPreparedQueries}}
+    result, err := q.exec(ctx, q.{{.FieldName}}, {{.ConstantName}}, {{.Arg.Params}})
+    {{- else if $.EmitMethodsWithDBArgument}}
+    result, err := db.ExecContext(ctx, {{.ConstantName}}, {{.Arg.Params}})
+    {{- else}}
+    result, err := q.db.ExecContext(ctx, {{.ConstantName}}, {{.Arg.Params}})
+    {{- end}}
+    if err != nil {
+        return 0, err
+    }
+    return result.LastInsertId()
+}
+{{end}}
+
 {{if eq .Cmd ":execresult"}}
 {{range .Comments}}//{{.}}
 {{end -}}

internal/endtoend/testdata/exec_lastid/go_postgresql_stdlib/query.sql

@@ -0,0 +1,4 @@
+CREATE TABLE bar (id integer(10) NOT NULL AUTO_INCREMENT PRIMARY KEY);
+
+-- name: InsertBar :execlastid
+INSERT INTO bar () VALUES ();

internal/endtoend/testdata/exec_lastid/go_postgresql_stdlib/sqlc.json

@@ -0,0 +1,13 @@
+{
+  "version": "1",
+  "packages": [
+    {
+      "path": "go",
+      "name": "querytest",
+      "engine": "mysql",
+      "schema": "query.sql",
+      "queries": "query.sql",
+      "emit_interface": true
+    }
+  ]
+}

internal/metadata/meta.go

@@ -16,6 +16,7 @@ const (
 	CmdExec       = ":exec"
 	CmdExecResult = ":execresult"
 	CmdExecRows   = ":execrows"
+	CmdExecLastId = ":execlastid"
 	CmdMany       = ":many"
 	CmdOne        = ":one"
 	CmdCopyFrom   = ":copyfrom"
@@ -83,15 +84,15 @@ func Parse(t string, commentStyle CommentSyntax) (string, string, error) {
 			part = part[:len(part)-1] // removes the trailing "*/" element
 		}
 		if len(part) == 2 {
-			return "", "", fmt.Errorf("missing query type [':one', ':many', ':exec', ':execrows', ':execresult', ':copyfrom', 'batchexec', 'batchmany', 'batchone']: %s", line)
+			return "", "", fmt.Errorf("missing query type [':one', ':many', ':exec', ':execrows', ':execlastid', ':execresult', ':copyfrom', 'batchexec', 'batchmany', 'batchone']: %s", line)
 		}
 		if len(part) != 4 {
 			return "", "", fmt.Errorf("invalid query comment: %s", line)
 		}
 		queryName := part[2]
 		queryType := strings.TrimSpace(part[3])
 		switch queryType {
-		case CmdOne, CmdMany, CmdExec, CmdExecResult, CmdExecRows, CmdCopyFrom, CmdBatchExec, CmdBatchMany, CmdBatchOne:
+		case CmdOne, CmdMany, CmdExec, CmdExecResult, CmdExecRows, CmdExecLastId, CmdCopyFrom, CmdBatchExec, CmdBatchMany, CmdBatchOne:
 		default:
 			return "", "", fmt.Errorf("invalid query type: %s", queryType)
 		}