检查表中的索引是否存在 [英] Check if index in table exist
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问题描述
我有问题;我必须在表格中检查一个字段。
I have problem; I must check in my program one field in table.
if(launchArgs.androidIntent.extras.notification.custom.test_field ~= nil)then...
当这个索引存在时一切正常,但是当它不存在时存在,我收到错误:
and when this index exist everything is ok, but when it isn't exist, I get an error :
Attempt to index field 'notification' (a nil value).
这是可以理解的。如何检查该索引是否存在?
And it is understandable. How check if that index exist?
推荐答案
试试这个
if (launchArgs and launchArgs.androidIntent and launchArgs.androidIntent.extras
and launchArgs.androidIntent.extras.notification and launchArgs.androidIntent.extras.notification.custom
and launchArgs.androidIntent.extras.notification.custom.test_field) then
-- do you stuff
end
此代码将检查每个表是否已设置。
This code will check if each table is set.
如果你确定启动args.androidIntent.extras总是设置你可以这样做
If you're sure launch args.androidIntent.extras is always set you can just do this
if(launchArgs.androidIntent.extras.notification and launchArgs.androidIntent.extras.notification.custom and launchArgs.androidIntent.extras.notification.custom.test_field)then
-- do your stuff
end
或者只是使用这个功能,我在其他答案中发布(在这里也有帮助)
function IndexScan(input,value,case,_type)
if (input and type(input) == 'table') then
if (_type) then
if (type(value) == _type and value == input) then
return true;
end
else
if (type(value) == 'table' and value == input) then
return true;
end
end
for key,object in pairs(input) do
if (case and type(input)=='string' and type(key)=='string') then
if (_type) then
if (value:lower() == key:lower() and type(object)==_type) then
return true;
elseif(type(object)=='table') then
return IndexScan(object,value,case,_type)
end
else
if (value:lower() == key:lower()) then
return true;
elseif(type(object)=='table') then
return IndexScan(object,value,case,_type)
end
end
else
if (_type) then
if (key == value and type(object)==_type) then
return true
elseif(type(object)=='table') then
return IndexScan(object,value,case,_type)
end
else
if (key == value) then
return true
elseif(type(object)=='table') then
return IndexScan(object,value,case,_type)
end
end
end
end
end
return false;
end
-- IndexScan(@param table(table), @param index(string), @param case-sensitive(true/false), @param type (index type, string/boolean/number/table ...))
-- checks if these two indexes were set any where in the launchArgs table and checks their type
if (IndexScan(launchArgs,"notification",false,"table") and IndexScan(launchArgs,"test_field",false,"string")) then
-- do your stuff
end
编辑:
修正了函数中的一些错误。
Fixed some mistake in the function.
编辑:
在作者修正了通知错误后更新了脚本。
Updated the script after the author fixed the Notification typo.
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