getOrFallback

import std.conv : to;

{
    const json = JSONValue([ "abc" : "def", "ghi" : "jkl" ]);

    {
        const value = getOrFallback(json, "abc");
        assert((value == "def"), value);
    }
    {
        const value = getOrFallback(json, "ghi");
        assert((value == "jkl"), value);
    }
    {
        const value = getOrFallback(json, "mno");
        assert((value == string.init), value);
    }
    {
        const value = getOrFallback(json, "pqr", "INVALID");
        assert((value == "INVALID"), value);
    }
}
{
    const json = JSONValue([ "123" : 123, "456" : 456 ]);

    {
        const value = getOrFallback!long(json, "123");
        assert((value == 123L), value.to!string);
    }
    {
        const value = getOrFallback!long(json, "456");
        assert((value == 456L), value.to!string);
    }
    {
        const value = getOrFallback!long(json, "789");
        assert((value == 0L), value.to!string);
    }
    {
        const value = getOrFallback!long(json, "012", 999);
        assert((value == 999L), value.to!string);
    }
}