mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-14 10:22:10 +00:00
58 lines
2.1 KiB
C++
58 lines
2.1 KiB
C++
#include <Functions/FunctionFactory.h>
|
|
#include <Functions/FunctionsVisitParam.h>
|
|
#include <Functions/FunctionsStringSearchToString.h>
|
|
|
|
|
|
namespace DB
|
|
{
|
|
|
|
struct ExtractString
|
|
{
|
|
static void extract(const UInt8 * pos, const UInt8 * end, ColumnString::Chars & res_data)
|
|
{
|
|
size_t old_size = res_data.size();
|
|
ReadBufferFromMemory in(pos, end - pos);
|
|
if (!tryReadJSONStringInto(res_data, in))
|
|
res_data.resize(old_size);
|
|
}
|
|
};
|
|
|
|
struct NameSimpleJSONExtractString { static constexpr auto name = "simpleJSONExtractString"; };
|
|
using FunctionSimpleJSONExtractString = FunctionsStringSearchToString<ExtractParamToStringImpl<ExtractString>, NameSimpleJSONExtractString>;
|
|
|
|
REGISTER_FUNCTION(VisitParamExtractString)
|
|
{
|
|
factory.registerFunction<FunctionSimpleJSONExtractString>(FunctionDocumentation{
|
|
.description = R"(Parses String in double quotes from the value of the field named field_name.
|
|
|
|
There is currently no support for code points in the format \uXXXX\uYYYY that are not from the basic multilingual plane (they are converted to CESU-8 instead of UTF-8).)",
|
|
.syntax = "simpleJSONExtractString(json, field_name)",
|
|
.arguments
|
|
= {{"json", "The JSON in which the field is searched for. String."},
|
|
{"field_name", "The name of the field to search for. String literal."}},
|
|
.returned_value = "It returns the value of a field as a String, including separators. The value is unescaped. It returns an empty "
|
|
"String: if the field doesn't contain a double quoted string, if unescaping fails or if the field doesn't exist.",
|
|
.examples
|
|
= {{.name = "simple",
|
|
.query = R"(CREATE TABLE jsons
|
|
(
|
|
json String
|
|
)
|
|
ENGINE = Memory;
|
|
|
|
INSERT INTO jsons VALUES ('{"foo":"\\n\\u0000"}');
|
|
INSERT INTO jsons VALUES ('{"foo":"\\u263"}');
|
|
INSERT INTO jsons VALUES ('{"foo":"\\u263a"}');
|
|
INSERT INTO jsons VALUES ('{"foo":"hello}');
|
|
|
|
SELECT simpleJSONExtractString(json, 'foo') FROM jsons ORDER BY json;)",
|
|
.result = R"(\n\0
|
|
|
|
☺
|
|
)"}},
|
|
.categories{"JSON"}});
|
|
factory.registerAlias("visitParamExtractString", "simpleJSONExtractString");
|
|
}
|
|
|
|
}
|