Digital Filters deal only with samples, right? I'm new to digital filters. So I'm trying to get things right and I can't find an explicit answer to my question on the internet.

Question: Digital filters only accept samples as input? I mean the input can not be zeros nor ones. It can only be samples. If that's the case, then the typical position for a digital filter would be after the receiver (I mean before converting to bits).

So receiver would be like: 

$$
\mbox{antenna} \rightarrow \mbox{amplifier} \rightarrow \mbox{Sampler} \rightarrow \mbox{Digital Filter} \rightarrow  \underbrace{\mbox{DAC}}_{\tiny \mbox{here I should have filtered samples}}
$$

Please correct me and kindly ignore any coding or LNAs and stuff like that.
You are almost right: digital filters do deal with samples, but a sample can be any numerical representation of a given signal value at a given instant (so in general, they may accept zeros or ones).

Moreover, a sample is usually represented by a binary word (e.g. 0001), so a digital filter actually deals with 0s and 1s.