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[TS] Support vectors, numerics, and strings with defaults #8896

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Merged
bjornharrtell merged 1 commit into from
Feb 23, 2026
+130 −32
Merged

[TS] Support vectors, numerics, and strings with defaults #8896

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114 changes: 87 additions & 27 deletions src/idl_gen_ts.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -522,7 +522,16 @@ class TsGenerator : public BaseGenerator {
case BASE_TYPE_BOOL:
return value.constant == "0" ? "false" : "true";

case BASE_TYPE_STRING:
case BASE_TYPE_STRING: {
// NOTE: Strings without a default value are parsed as "0" by
// the parser, so therefore we have to treat "0" as a null-signifying
// value.
if (value.constant == "0" || value.constant == "null") {
return "null";
} else {
return "\"" + value.constant + "\"";
}
}
case BASE_TYPE_UNION:
case BASE_TYPE_STRUCT: {
return null_keyword_;
Expand Down Expand Up @@ -1334,10 +1343,9 @@ class TsGenerator : public BaseGenerator {
// Emit a scalar field
const auto is_string = IsString(field.value.type);
if (IsScalar(field.value.type.base_type) || is_string) {
const auto has_null_default = is_string || HasNullDefault(field);

field_type += GenTypeName(imports, field, field.value.type, false,
has_null_default);
field_type +=
GenTypeName(imports, field, field.value.type, false,
!HasDefaultValue(field) || HasNullDefault(field));
field_val = "this." + namer_.Method(field) + "()";

if (field.value.type.base_type != BASE_TYPE_STRING) {
Expand Down Expand Up @@ -1731,21 +1739,22 @@ class TsGenerator : public BaseGenerator {
offset_prefix = " const offset = " + GenBBAccess() +
".__offset(this.bb_pos, " +
NumToString(field.value.offset) + ");\n";
offset_prefix += " return offset ? ";
offset_prefix += " return ";
}

// Emit a scalar field
const auto is_string = IsString(field.value.type);
if (IsScalar(field.value.type.base_type) || is_string) {
const auto has_null_default = is_string || HasNullDefault(field);
const auto has_null_default =
!field.IsRequired() && !HasDefaultValue(field);

GenDocComment(field.doc_comment, code_ptr);
std::string prefix = namer_.Method(field) + "(";
if (is_string) {
code += prefix + "):string|" + null_keyword_ + "\n";
code += prefix + "):" + (has_null_default ? "string|" + null_keyword_ : "string") + "\n";
code +=
prefix + "optionalEncoding:flatbuffers.Encoding" + "):" +
GenTypeName(imports, struct_def, field.value.type, false, true) +
GenTypeName(imports, struct_def, field.value.type, false, has_null_default) +
"\n";
code += prefix + "optionalEncoding?:any";
} else {
Expand Down Expand Up @@ -1774,9 +1783,16 @@ class TsGenerator : public BaseGenerator {
if (is_string) {
index += ", optionalEncoding";
}
code +=
offset_prefix + GenGetter(field.value.type, "(" + index + ")");
if (field.value.type.base_type != BASE_TYPE_ARRAY) {
if (field.IsRequired()) {
code +=
offset_prefix + GenGetter(field.value.type, "(" + index + ")");
;
} else {
code += offset_prefix + "offset ? " +
GenGetter(field.value.type, "(" + index + ")");
}
if (field.value.type.base_type != BASE_TYPE_ARRAY &&
!field.IsRequired()) {
code += " : " + GenDefaultValue(field, imports);
}
code += ";\n";
Expand All @@ -1801,8 +1817,8 @@ class TsGenerator : public BaseGenerator {
code +=
MaybeAdd(field.value.offset) + ", " + GenBBAccess() + ");\n";
} else {
code += offset_prefix + "(obj || " + GenerateNewExpression(type) +
").__init(";
code += offset_prefix + "offset ? (obj || " +
GenerateNewExpression(type) + ").__init(";
code += field.value.type.struct_def->fixed
? "this.bb_pos + offset"
: GenBBAccess() + ".__indirect(this.bb_pos + offset)";
Expand Down Expand Up @@ -1960,7 +1976,7 @@ class TsGenerator : public BaseGenerator {
code += "):" + vectortypename + "|" + null_keyword_ + " {\n";

if (vectortype.base_type == BASE_TYPE_STRUCT) {
code += offset_prefix + "(obj || " +
code += offset_prefix + "offset ? (obj || " +
GenerateNewExpression(vectortypename);
code += ").__init(";
code += vectortype.struct_def->fixed
Expand All @@ -1973,7 +1989,8 @@ class TsGenerator : public BaseGenerator {
} else if (IsString(vectortype)) {
index += ", optionalEncoding";
}
code += offset_prefix + GenGetter(vectortype, "(" + index + ")");
code += offset_prefix + "offset ? " +
GenGetter(vectortype, "(" + index + ")");
}
code += " : ";
if (field.value.type.element == BASE_TYPE_BOOL) {
Expand Down Expand Up @@ -2005,7 +2022,7 @@ class TsGenerator : public BaseGenerator {
" "
"{\n";

code += offset_prefix +
code += offset_prefix + "offset ? " +
GenGetter(field.value.type, "(obj, this.bb_pos + offset)") +
" : " + null_keyword_ + ";\n";
break;
Expand Down Expand Up @@ -2058,7 +2075,7 @@ class TsGenerator : public BaseGenerator {
// Emit a length helper
GenDocComment(code_ptr);
code += namer_.Method(field, "Length");
code += "():number {\n" + offset_prefix;
code += "():number {\n" + offset_prefix + "offset ? ";

code +=
GenBBAccess() + ".__vector_len(this.bb_pos + offset) : 0;\n}\n\n";
Expand All @@ -2069,15 +2086,30 @@ class TsGenerator : public BaseGenerator {
GenDocComment(code_ptr);

code += namer_.Method(field, "Array");
code += "():" + GenType(vectorType) + "Array|" + null_keyword_ +
" {\n" + offset_prefix;

code += "new " + GenType(vectorType) + "Array(" + GenBBAccess() +
".bytes().buffer, " + GenBBAccess() +
".bytes().byteOffset + " + GenBBAccess() +
".__vector(this.bb_pos + offset), " + GenBBAccess() +
".__vector_len(this.bb_pos + offset)) : " + null_keyword_ +
";\n}\n\n";

std::string return_type =
(field.IsRequired() || HasDefaultValue(field))
? "Array"
: ("Array|" + null_keyword_);
if (field.IsRequired()) {
code += "():" + GenType(vectorType) + return_type + " {\n" +
offset_prefix + "new " + GenType(vectorType) + "Array(" +
GenBBAccess() + ".bytes().buffer, " + GenBBAccess() +
".bytes().byteOffset + " + GenBBAccess() +
".__vector(this.bb_pos + offset), " + GenBBAccess() +
".__vector_len(this.bb_pos + offset));\n}\n\n";
} else {
std::string value = HasDefaultValue(field)
? "new " + GenType(vectorType) + "Array()"
: "null";
code += "():" + GenType(vectorType) + return_type + " {\n" +
offset_prefix + "offset ? new " + GenType(vectorType) +
"Array(" + GenBBAccess() + ".bytes().buffer, " +
GenBBAccess() + ".bytes().byteOffset + " + GenBBAccess() +
".__vector(this.bb_pos + offset), " + GenBBAccess() +
".__vector_len(this.bb_pos + offset)) : " + value +
";\n}\n\n";
}
}
}
}
Expand Down Expand Up @@ -2308,6 +2340,34 @@ class TsGenerator : public BaseGenerator {
return field.IsOptional() && field.value.constant == "null";
}

static bool HasDefaultValue(const FieldDef& field) {
switch (field.value.type.base_type) {
// These types can't have defaults
case BASE_TYPE_UNION:
case BASE_TYPE_STRUCT: {
return false;
}

// Arrays always have a default (empty array)
case BASE_TYPE_ARRAY:
return true;

// The only supported default for vectors is []
case BASE_TYPE_VECTOR:
return field.value.constant == "[]";

// Even strings are presumed to be null-default if the default value is
// "0", this is intended behavior.
case BASE_TYPE_STRING: {
return field.value.constant != "0" && field.value.constant != "null";
}

default: {
return field.value.constant != "null";
}
}
}

std::string GetArgType(import_set& imports, const Definition& owner,
const FieldDef& field, bool allowNull) {
return GenTypeName(imports, owner, field.value.type, true,
Expand Down
3 changes: 2 additions & 1 deletion src/idl_parser.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2809,7 +2809,8 @@ bool Parser::SupportsOptionalScalars() const {
bool Parser::SupportsDefaultVectorsAndStrings() const {
static FLATBUFFERS_CONSTEXPR unsigned long supported_langs =
IDLOptions::kRust | IDLOptions::kSwift | IDLOptions::kNim |
IDLOptions::kCpp | IDLOptions::kBinary | IDLOptions::kJson;
IDLOptions::kCpp | IDLOptions::kBinary | IDLOptions::kJson |
IDLOptions::kTs;
return !(opts.lang_to_generate & ~supported_langs);
}

Expand Down
23 changes: 23 additions & 0 deletions tests/even_more_defaults.fbs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@

enum ABC: int { A, B, C }

struct EvenMoreStruct {
g:[int64:2];
}

table EvenMoreDefaults {
str: EvenMoreStruct;
ints: [int] = [];
floats: [float] = [ ];
float_optional: [float];
bytes_optional: [ubyte];
floats_required: [float] (required);
empty_string: string = "";
some_string: string = "some";
zero_string: string = "0";
a_string:string (key);
required_string: string (required);
abcs: [ABC] = [];
bools: [bool] = [];
one_bool: bool = true;
}
14 changes: 14 additions & 0 deletions tests/ts/TypeScriptTest.py
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Expand Up @@ -87,6 +87,20 @@ def esbuild(input, output):
)
esbuild("monster_test.ts", "monster_test_generated.cjs")

flatc(
options=[
"--ts",
"--reflect-names",
"--gen-name-strings",
"--gen-mutable",
"--gen-object-api",
"--ts-entry-points",
"--ts-flat-files",
],
schema="../even_more_defaults.fbs",
include="../include_test",
)

flatc(
options=["--gen-object-api", "-b"],
schema="../monster_test.fbs",
Expand Down
8 changes: 4 additions & 4 deletions tests/ts/my-game/example/monster.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -81,11 +81,11 @@ mutate_hp(value:number):boolean {
return true;
}

name():string|null
name(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
name(optionalEncoding?:any):string|Uint8Array|null {
name():string
name(optionalEncoding:flatbuffers.Encoding):string|Uint8Array
name(optionalEncoding?:any):string|Uint8Array {
const offset = this.bb!.__offset(this.bb_pos, 10);
return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
return this.bb!.__string(this.bb_pos + offset, optionalEncoding);
}

inventory(index: number):number|null {
Expand Down
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