Significant Accounting Policies - Calculation of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Jan. 31, 2022	Oct. 31, 2021	Jul. 31, 2021	Jan. 31, 2021	Oct. 31, 2020	Jul. 31, 2020	Jan. 31, 2022	Jan. 31, 2021
Basic and diluted net (loss) income per share computation
Net income attributable to common stockholders	$ 787	$ 277	$ (172)	$ 959	$ 1	$ 75	$ 892	$ 1,035
Weighted Average common shares - basic (in shares)	13,500,444			13,371,613			13,170,880	12,974,470
Basic net income per share (in dollars per share)	$ 0.06			$ 0.07			$ 0.07	$ 0.08
Net income available to common stockholders	$ 787			$ 959			$ 892	$ 1,035
Incremental shares from assumed exercise of warrants and stock options (in shares)	886,565			1,135,542			1,007,202	1,535,810
Adjusted weighted average share - diluted (in shares)	14,387,009			14,507,155			14,178,082	14,510,280
Diluted net income per share (in dollars per share)	$ 0.05			$ 0.07			$ 0.06	$ 0.07