So in the season two finale for mlp:friendship is magic it's revealed that's there's a whole nation of changlings that feeds on love kept segregated from the rest of pony society. Now I get that feeding off love is evil and all but is that really enough for princess Celestia to condemn a people to starvation and death? Could they not just hold a annual 'feed the changlings love' festival? It doesn't sit right with me that instead of spreading friendship with their moth eaten cousins equrstria condemns them all to death.
It is strongly implied that up to that point taking the love they needed by force and trickery is indeed the only thing the changeling have planned to do. It is unclear to what extend this is due to their queen being actually evil at heart or yet another "victim" of the circumstances.
The extended cannon from the comics do include a few instance that would seem to indicate that the queen is indeed inherently bad and love to hurt others, but it is unclear if the show still consider those episode canonical. That said, it is interesting to consider that the comics imply that the changeling were born from an incident involving a cursed lake of tar, powerful magic and... a mosquito.
And what do mosquitoes do? They suck blood from other creatures to survive.
That said, back to your question, there are multiple evidences that as far as season 2 finale goes the queen of the changeling does not consider "asking for friendship" a valid option. This is probably the reason anyone attacked by the changeling army couldn't just try a "let's talk this out" approach. As for the comics... it is worth noticing that in the Chrysalis return story arc the changeling attack a tribe of creature that don't oppose any resistance to them and keep loving them no matter what - this does not stop the changeling from attacking them.
So, to put it simple: up to season 2 there haven't been similar attempts because Queen Chrysalis won't accept them.