JSON for Modern C++ 3.7.3

accept
accept
accept
allocator_type
array
array_t
at
at
at
at
at
at
back
back
basic_json
basic_json
basic_json
basic_json
basic_json
basic_json
basic_json
basic_json
basic_json
basic_json
begin
begin
binary
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clear
const_iterator
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contains
contains
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detail::external_constructor
diff
difference_type
dump
emplace
emplace_back
empty
end
end
erase
erase
erase
erase
error_handler_t
exception
find
find
flatten
from_bson
from_bson
from_bson
from_cbor
from_cbor
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from_msgpack
from_msgpack
from_msgpack
from_ubjson
from_ubjson
from_ubjson
front
front
get
get
get
get
get
get
get_allocator
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get_binary
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iterator
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json_sax_t
json_serializer
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meta
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operator value_t
operator ValueType
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reference
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~basic_json
| ## ◆ diff()
static basic_json nlohmann::basic_json::diff | ( | const basic_json & | source,
|  | const basic_json & | target,
|  | const std::string & | path = `""`
| ) |  |
| inlinestatic
  Creates a JSON Patch so that value source can be changed into the value target by calling patch function. Invariant For two JSON values source and target, the following code yields always `true`: source.patch(diff(source, target)) == target; Note Currently, only `remove`, `add`, and `replace` operations are generated. Parameters
  [in] | source | JSON value to compare from
  [in] | target | JSON value to compare against
  [in] | path | helper value to create JSON pointers
  Returns a JSON patch to convert the source to target Complexity Linear in the lengths of source and target. Example The following code shows how a JSON patch is created as a diff for two JSON values. 1 #include <iostream> 2 #include <iomanip> 3 #include <nlohmann/json.hpp> 4 5 using json = nlohmann::json; 6 7 int main() 8 { 9 // the source document 10 json source = R"( 11 { 12 "baz": "qux", 13 "foo": "bar" 14 } 15 )"_json; 16 17 // the target document 18 json target = R"( 19 { 20 "baz": "boo", 21 "hello": [ 22 "world" 23 ] 24 } 25 )"_json; 26 27 // create the patch 28 json patch = json::diff(source, target); 29 30 // roundtrip 31 json patched_source = source.patch(patch); 32 33 // output patch and roundtrip result 34 std::cout << std::setw(4) << patch << "\n\n" 35 << std::setw(4) << patched_source << std::endl; 36 } Output (play with this example online):
      [
          {
              "op": "replace",
              "path": "/baz",
              "value": "boo"
          },
          {
              "op": "remove",
              "path": "/foo"
          },
          {
              "op": "add",
              "path": "/hello",
              "value": [
                  "world"
              ]
          }
      ]

      {
          "baz": "boo",
          "hello": [
              "world"
          ]
      }
  The example code above can be translated with
      g++ -std=c++11 -Isingle_include doc/examples/diff.cpp -o diff
See also patch – apply a JSON patch merge_patch – apply a JSON Merge Patch RFC 6902 (JSON Patch) Since version 2.0.0 Definition at line 24183 of file json.hpp.

nlohmann::basic_json::diff
static basic_json diff(const basic_json &source, const basic_json &target, const std::string &path="")
creates a diff as a JSON patch
Definition: json.hpp:24183
nlohmann::json
basic_json<> json
default JSON class
Definition: json.hpp:2774
nlohmann::basic_json::patch
basic_json patch(const basic_json &json_patch) const
applies a JSON patch
Definition: json.hpp:23887