how to completely remove json array element (using jsoncpp)

Question

I am using jsoncpp, I have a set of data as below, I want to search some node and remove the array element, some how when I remove, it become {}, is that possible to completely remove with {}?

Data before remove:

{
    "any" : [
    {
        "any_id" : "a1",
        "infos" : [
        {
            "info_id" : "i1",
            "path" : "",
            "version" : "1.0"
        }
        ]
    },
    {
        "any_id" : "a2",
        "infos" : [
        {
            "info_id" : "i1",
            "path" : "",
            "version" : "1.0"
        },
        {
            "info_id" : "i2",
            "path" : "D:\\",
            "version" : "1.0"
        },
        {
            "info_id" : "i3",
            "path" : "",
            "version" : "1.0"
        },
        {
            "info_id" : "i4",
            "path" : "D:\\",
            "version" : "1.0"
        }
        ]
    },
    {
        "any_id" : "a3",
        "infos" : [
        {
            "info_id" : "i4",
            "path" : "",
            "version" : "1.0"
        }
        ]
    }
    ]
}

Data after remove:

{
    "any" : [
    {
        "any_id" : "a1",
        "infos" : [
        {
            "info_id" : "i1",
            "path" : "",
            "version" : "1.0"
        }
        ]
    },
    {
        "any_id" : "a2",
        "infos" : [
        {
            "info_id" : "i1",
            "path" : "",
            "version" : "1.0"
        },
        {
        },
        {
            "info_id" : "i3",
            "path" : "",
            "version" : "1.0"
        },
        {
        }
        ]
    },
    {
        "any_id" : "a3",
        "infos" : [
        {
            "info_id" : "i4",
            "path" : "",
            "version" : "1.0"
        }
        ]
    }
    ]
}

in C++, I have the following code, look for any_id and path to remove array element:

for (Json::ValueIterator &itr_any = data["any"].begin();
        itr_any != data["any"].end(); ++itr_any)
    {
        if (0 == _stricmp((*itr_any)["any_id"].asString().c_str(), "a2"))
        {
            for (Json::ValueIterator &itr_res = (*itr_any)["infos"].begin();
                itr_res != (*itr_any)["infos"].end(); ++itr_res)
            {
                if (0 == _stricmp((*itr_res)["path"].asString().c_str(), "D:\\"))
                {
                    (*itr_res).clear();
                }
            }
        }
    }

Sga · Accepted Answer · 2016-10-18 10:37:39Z

2

With (*itr_res).clear(); you are in fact emptying the content of the object in the chosen array.

JsonCpp APIs don't expose methods to manipulate arrays, so the easiest way to remove items is to build a new array excluding matching elements:

for (Json::ValueIterator &itr_any = data["any"].begin(); itr_any != data["any"].end(); ++itr_any)
    if (0 == _stricmp((*itr_any)["any_id"].asString().c_str(), "a2"))
    {
        Json::Value newArray = Json::arrayValue;
        for (Json::ValueIterator &itr_res = (*itr_any)["infos"].begin(); itr_res != (*itr_any)["infos"].end(); ++itr_res)
            if (_stricmp((*itr_res)["path"].asString().c_str(), "D:\\"))
                newArray.append((*itr_res));
        (*itr_any)["infos"] = newArray;
    }

answered Oct 18, 2016 at 10:37

Sga

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