formats::json::StringBuilder Class Reference

#include <userver/formats/json/string_builder.hpp>

Detailed Description

SAX like builder of JSON string. Use with extreme caution and only in performance critical part of your code.

Prefer using WriteToStream function to add data to the StringBuilder.

Example usage:

namespace my_namespace {
 
struct MyKeyValue {
  std::string field1;
  int field2;
};
 
// The function must be declared in the namespace of your type
inline void WriteToStream(const MyKeyValue& data,
                          formats::json::StringBuilder& sw) {
  // A class that adds '{' in the constructor and '}' in the destructor to JSON
  formats::json::StringBuilder::ObjectGuard guard{sw};
 
  sw.Key("field1");
  // Use the WriteToStream functions for values, don't work with StringBuilder
  // directly
  WriteToStream(data.field1, sw);
 
  sw.Key("field2");
  WriteToStream(data.field2, sw);
}
 
TEST(JsonStringBuilder, ExampleUsage) {
  StringBuilder sb;
  MyKeyValue data = {"one", 1};
  WriteToStream(data, sb);
  ASSERT_EQ(sb.GetString(), "{\"field1\":\"one\",\"field2\":1}");
}
 
}  // namespace my_namespace

See also

Formats (JSON, YAML, BSON, ...)

Definition at line 36 of file string_builder.hpp.

Inheritance diagram for formats::json::StringBuilder:

Collaboration diagram for formats::json::StringBuilder:

Classes
class	ArrayGuard
class	ObjectGuard

Public Types
using	Value = formats::json::Value

Public Member Functions
std::string	GetString () const
std::string_view	GetStringView () const
void	WriteNull ()
void	WriteString (std::string_view value)
void	WriteBool (bool value)
void	WriteInt64 (int64_t value)
void	WriteUInt64 (uint64_t value)
void	WriteDouble (double value)
void	Key (std::string_view sw)
	ONLY for objects/dicts: write key.
void	WriteRawString (std::string_view value)
	Appends raw data.
void	WriteValue (const Value &value)

Member Typedef Documentation

Value

using formats::json::StringBuilder::Value = formats::json::Value

Definition at line 39 of file string_builder.hpp.

Member Function Documentation

GetString()

std::string formats::json::StringBuilder::GetString

(

)

const

Returns

JSON string

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The documentation for this class was generated from the following file:

• userver/formats/json/string_builder.hpp