Note 15 - Stock-based Compensation - Summary of Outstanding Unvested RSUs (Details) - Restricted Stock Units (RSUs) [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jul. 31, 2022	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2019
Number of Restricted Stock Units (in shares)	836,034	997,612	1,615,000	465,000
Grant Date Fair Value (in dollars per share)	$ 2.61	$ 1.42	$ 0.92	$ 0.94
Remaining Life (Year)	2 years 1 month 13 days
Aggregate Intrinsic Value	$ 3,510
July 16, 2020 [Member]
Number of Restricted Stock Units (in shares)	217,498
Grant Date Fair Value (in dollars per share)	$ 0.91
Remaining Life (Year)	11 months 15 days
Aggregate Intrinsic Value	$ 913
July 21, 2021 [Member]
Number of Restricted Stock Units (in shares)	271,746
Grant Date Fair Value (in dollars per share)	$ 2.15
Remaining Life (Year)	1 year 11 months 23 days
Aggregate Intrinsic Value	$ 1,141
May 01, 2022 [Member]
Number of Restricted Stock Units (in shares)	58,824
Grant Date Fair Value (in dollars per share)	$ 4.25
Remaining Life (Year)	2 years 9 months
Aggregate Intrinsic Value	$ 247
July 29, 2022 [Member]
Number of Restricted Stock Units (in shares)	287,966
Grant Date Fair Value (in dollars per share)	$ 3.98
Remaining Life (Year)	3 years
Aggregate Intrinsic Value	$ 1,209