How to access previous key/value pair in ng-repeat?

Question

My AngularJs app reads a json file having key/value pairs. The key/value pairs are generated by a java program using HashMap.

I am trying to generate HTML using ng-repeat directive in AngularJs in the following manner.

<li ng-repeat="(line, lineContents) in errorsFromLogFile">
    {{line}} - {{lineContents}} 
</li>

I also want to access the previous (key / value) pair.

Gone through these stackoverflow links How to obtain previous item in ng-repeat, Compare values inside ng-repeat and tried to access the previous key as

{{ errorsFromLogFile[$index-1].line }}

but it gives nothing. How to access previous key/value in this case?

The json file looks like this

- errorsFromLogFile: {
     7308: "/tmp/cct7oRJm.s:2099392: Warning: .stabs: description field '11668' too big, try a different debug format",
     7309: "/tmp/cct7oRJm.s:2099393: Warning: .stabs: description field '120d3' too big, try a different debug format",
     7310: "/tmp/cct7oRJm.s:2099394: Warning: .stabs: description field '128a6' too big, try a different debug format",
     7311: "/tmp/cct7oRJm.s:2099395: Warning: .stabs: description field '13046' too big, try a different debug format",
     7312: "/tmp/cct7oRJm.s:2099396: Warning: .stabs: description field '1386c' too big, try a different debug format",
   }

if you are not using any filter on ng-repeat then you could easily get the track of past record using `errorsFromLogFile[$index-1] == errorsFromLogFile[$index]` — Pankaj Parkar, Aug 27 '15 at 17:44
Here http://plnkr.co/edit/G1CSS7g99TrrmemhH9Tt?p=preview everything works fine. — Diana R, Aug 27 '15 at 17:48
@PankajParkar This works for arrays not objects. The json returned is an object map. — r_k, Aug 28 '15 at 11:57
@DianaR errorsFromLogFile is an array of objects so it works. But will not work for object map. — r_k, Aug 28 '15 at 11:58
Oh. than this changes the solution. Here is a working one: http://plnkr.co/edit/wGIBxWNIm6Z0MoDH1Xys?p=preview — Diana R, Aug 28 '15 at 12:57

PSL · Accepted Answer · 2015-08-27T18:02:50.527

1

You may have to use internal property $$prevSibling which gives the previous sibling scope and in this case previous scope created by ng-repeat. This is because you are using an object map and not Array. errorsFromLogFile[$index-1] will not work in array of objects because it just means that you are trying to access value of property index from the array, i.e errorsFromLogFile[0], errorsFromLogFile[1] etc.

i.e {{$$prevSibling.line}} and {{$$prevSibling.lineContents}} which should work, but is not advisable to use private properties on scope.

Another better suggestion is to convert it to array of objects and just have regular ng-repeat iteration syntax and get the previous item using the index.

edited Aug 27 '15 at 18:02

answered Aug 27 '15 at 17:57

PSL

123,204
21
253
243

Thanks. This solves the issue. Since I am using object map not Array, and accessing keys in a serial fashion is not possible [Access first property of an object](http://stackoverflow.com/questions/983267/access-the-first-property-of-an-object). Now I get all the keys _(lines)_ from the object _(errorsFromLogFile)_ and use **ng-repeat** over it. – r_k Aug 28 '15 at 12:03

How to access previous key/value pair in ng-repeat?

1 Answers1