Note 11 - Capital Stock (Details Textual) - USD ($)		3 Months Ended	9 Months Ended
	Oct. 03, 2018	Apr. 30, 2019	Apr. 30, 2019	Jul. 31, 2018
Shares Issued, Price Per Share		$ 1.33	$ 1.33
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 1.94	$ 1.94	$ 1.97
Share Price	$ 1.54
Number of Warrants Exchanged for Common Shares		11,000,000	11,000,000
Stock Issued During the Period, Shares, Issued in Exchange for Warrants		750,000	750,000
Class of Warrant or Right Cancelled, Weighted Average Exercise Price		$ 2.30	$ 2.30
Warrants, Carrying Value Per Share		$ 0.45	$ 0.45
Carrying Value of Warrants		$ 4,950,000
Fair Value Common Shares Issued for Warrants Exchanged		997,500	$ 997,500
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises on a Forfeiture Basis			151,500
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period			52,735
Proceeds from Warrant Exercises		$ 4,822,357
Class of Warrant or Right, Exercised During Period		3,999,881
Class of Warrant or Right, Exercised During Period, Exercise Price		$ 1.21
October 2018 Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right	1
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 2.05
Warrants and Rights Outstanding, Term	2 years 180 days
Equity Financing [Member]
Number of Units Issued During Period	12,613,049
Shares Issued, Price Per Share	$ 1.60	$ 1.60	$ 1.60
Proceeds from Issuance or Sale of Equity, Total	$ 20,180,878
Number of Shares per Unit Issued	1
Number of Warrants per Unit	0.5
Over-Allotment Option [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 2.05
Warrants and Rights Outstanding, Term	2 years 180 days
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	756,782