Put an item in Amazon DynamoDB with AWS SDK CPP using as input the item in JSON format

Question

Is there any easy way to put an item in Amazon DynamoDB with AWS SDK CPP using as input the item in JSON format? Something like

Aws::DynamoDB::Model::PutItemRequest request;
request.SetTableName(table);
request.FunctionThatSetsAllAttributesParsingAJsonString(json_string);

Or is it always necessary to set each attribute and its type?

Aws::DynamoDB::Model::PutItemRequest request;
request.SetTableName(table);
Aws::DynamoDB::Model::AttributeValue val1;
val1.SetS(str);
request.AddItem(key, val1);
Aws::DynamoDB::Model::AttributeValue val2;
...

I do not believe there is an interface that accepts a JSON string but you could iterate over the keys of the JSON, populate an AttributeValue, and add that to the PutItemRequest in a somewhat generic fashion. Presumably you really want/need to use C++ but, if not, there are much easier ways to do this in other languages. — jarmod
– jarmod, Commented Apr 15, 2021 at 15:17

Medical physicist · Accepted Answer · 2021-04-23 08:12:29Z

If the JSON object follows Amazon DynamoDB JSON format, you can easily convert it into an Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue> object. For instance, for a Jsoncpp Json::Value object:

Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue> json2atts(const Json::Value& json) {
    try {
        Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue> amap;
        Aws::Utils::Json::JsonValue jval(Json::FastWriter().write(json));
        if (!jval.WasParseSuccessful()) {
            throw exception("Failed to parse input JSON");
        };
        Aws::Utils::Json::JsonView jview = jval.View();
        Aws::Map<Aws::String, Aws::Utils::Json::JsonView> jmap = jview.GetAllObjects();
        for(auto& i : jmap) {
            amap[i.first] = i.second.AsObject();
        };
        return amap;
    }
    catch (std::exception &e) { 
       ...
    };
};

Then, to put the Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue> object:

Aws::DynamoDB::Model::PutItemRequest request;
request.SetTableName(table);
request.SetItem(amap);

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