Compound Index filtering question

[Andrew Holbrook]

Hi,

Just discovered your library today after futzing around the past 2 weeks with another IndexedDB library with confusing (and often outdated) documentation.  Great work!

I have a dataset that is structured like so:

Animal | NumberOfLegs | FurColor

Is there a way to create a single compound index, for example [Animal + NumberOfLegs + FurColor] where I can filter only by 1 or two of those, eg.

db.data.where('[Animal+NumberOfLegs+FurColor]').equals([null,'4','brown']) or 

db.data.where('[Animal+NumberOfLegs+FurColor]').equals(['spiders,'8',null])

Otherwise, I assume I can make combinations of indices, but the number or indices will add up quickly.

Thanks!

Drew

[David Fahlander]

Hi!

You can always do queries on the leading keys (using where('[Animal+NumberOfLegs+FurColor]').between(["Horse",4, ""], ["Monkey", 2, '\uffff'])) but if you want to search on trailing keys you need to index them separately. Mapping your specific example to an implementation, you would write:

db.version(x).stores({

    data: 'Id, [Animal+NumberOfLegs+FurColor], [NumberOfLegs+FurColor]'

});

// Your sample: db.data.where('[Animal+NumberOfLegs+FurColor]').equals([null,'4','brown']) would instead be:

db.data.where('[NumberOfLegs+FurColor]').equals(['4','brown'])

// Your sample: db.data.where('[Animal+NumberOfLegs+FurColor]').equals(['spiders,'8',null]) would instead be:

db.data.where('[Animal+NumberOfLegs+FurColor]').between(['spiders', 8, ''], ['spiders', 8, '\uffff'])

[Andrew Holbrook]

Thanks, David!

[Andrew Holbrook]

To tag onto this, is there an equivalent "startsWith" compound index command?  Using the example below (getting all 8 legged spiders whose color starts with "b"), would it be:

db.data.where('[Animal+NumberOfLegs+FurColor]').between(['spiders', 8, 'b'], ['spiders', 8, '\uffff'])

Thanks!

[Andrew Holbrook]

And to answer my own question, yes.

[David Fahlander]

Yes, but replace "\uffff" with "b\uffff".

[vali....@gmail.com]

Hi David,
Thanks for your help with quick responses. Even i got into some trouble like same as Andrew. This is what i'm trying to do.

login ='jh...@gmail.com';
time = new Date().getTime();
lowerBound = [login,0,'file-transfer'];
upperBound = [login,time,'file-transfer'];
transcriptIndex = "[login+dateInMilliseconds+label]";
db.chatTranscripts.where(transcriptIndex).between(lowerBound,upperBound).reverse().toArray(function(data){
console.log(data);

}).catch(function(error){
console.error(error);
});

But the query is giving all objects with the current index. Basically i was trying to implement filters. Please help me with this and let me know if any further information needed.

[raymon...@gmail.com]

On Tuesday, May 26, 2015 at 9:49:44 PM UTC-5, Andrew Holbrook wrote:
> Hi,
>
>
> Just discovered your library today after futzing around the past 2 weeks with another IndexedDB library with confusing (and often outdated) documentation.  Great work!
>

I'm trying to get this too. I've got "people" objects and I want to index on first and last name:

myDb.version(1).stores({
employees:"++id,&email,[name.first+name.last]"
});

I've got a person in the db, aaron boyd, and if I search for a/b like so:

myDb.employees.where("[name.first+name.last]").startsWithIgnoreCase([fName,lName]).each(function(emp) {
console.log('found match '+emp.name.first);
});

I'd expect to find it. Shouldn't that work?

[Raymond Camden]

So I realize my where should not have [ ] in it. But removing it didn't help.

[Raymond Camden]

Ok so I was wrong, [] was required. :)

So I can make this work:

    myDb.employees.where("[name.first+name.last]").equals([fName,lName]).each(function(emp) {
        console.log('eq found match '+emp.name.first);
    });   

but not a startsWithIgnoreCase example.

[Raymond Camden]

And as an aside, I also tried storing first name and last name in the
'root' of my object to see if that would help, but it did not.

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Email : raymon...@gmail.com
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[David Fahlander]

Unfortunately, startsWith () and startsWithIgnoreCase () cannot be used with arrays / compound keys but requires a string as its single argument.

You could use the between () operator but then it would only be able to compare case sensitively. (Similar to earlier question in this thread.)

[David Fahlander]

@vali, to answer your question, you would have to index like this :

"[login+label+dateInMilliseconds]"

Instead of :

"[login+dateInMilliseconds+label]"

And then query accordingly. Otherwise ask labels for that login may be returned

[Raymond Camden]

Fair enough - is that documented?

[Vali Shah]

Hi David, 
  Thanks a lot. That solution worked. I made a mistake while configuring index.