By introducing the attractive dipole–dipole interaction, we provide a proposal to buffer the matter-wave soliton in a one-dimensional discrete lattice, which is divided into three parts with different local potentials produced by the external field modulation. Our study shows that, for sufficiently small initial phase tilt of the matter wave and deep enough potential well, the soliton will be trapped in the lattice. Otherwise, the soliton will propagate through the lattice. It appears that under certain conditions such a condensate system acts as a buffer, which can be used to temporarily store the matter wave. Meanwhile, in this buffer, the matter-wave soliton performs an unidirectional propagation, which makes it serve as a matter wave diode. The norm distribution in the lattice with respect to the initial phase tilt of the input wave is discussed, and it suggests there exists a critical phase tilt, below which the soliton will be trapped in the lattice.