Note 12 - Capital Stock (Details Textual) - USD ($)			12 Months Ended
	Oct. 03, 2018	Jan. 20, 2017	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017	Mar. 14, 2019	Jul. 31, 2016
Shares Issued, Price Per Share			$ 1.33
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 1.94	$ 1.97	$ 1.78	$ 1.33	$ 1.65
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						11,000,000
Share Price	$ 1.54	$ 1.54
Class of Warrant or Right Outstanding, Issued			7,063,253	11,358,728	9,571,929
Number of Warrants Exchanged for Common Shares			11,000,000
Stock Issued During the Period, Shares, Issued in Exchange for Warrants			750,000
Class of Warrant or Right Cancelled, Weighted Average Exercise Price			$ 2.30
Warrants, Carrying Value Per Share			$ 0.45
Carrying Value of Warrants			$ 4,950,000
Fair Value Common Shares Issued for Warrants Exchanged			997,500
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
January 2017 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
Warrants and Rights Outstanding, Term		3 years
The 2018 October Offering [Member]
Number of Units Issued During Period	12,613,049
Shares Issued, Price Per Share	$ 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	$ 2
Warrants and Rights Outstanding, Term	2 years 180 days	3 years
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	756,782	906,516
The 2017 Offering [Member]
Number of Units Issued During Period		17,330,836
Shares Issued, Price Per Share		$ 1.50
Proceeds from Issuance or Sale of Equity, Total		$ 25,996,254
Number of Shares per Unit Issued		1
Number of Warrants per Unit		0.5
Class of Warrant or Right Outstanding, Issued		9,571,929