breezejs: issue with FetchFromLocalCache strategy when using Skip

Question

Consider the following code :

 function search(filter) {
            var query = breeze.EntityQuery
                .from("Mandates").skip(offset).take(pageSize).inlineCount(true);


            if (queryParamCache[cacheObj] > 0) {
                query = query.using(breeze.FetchStrategy.FromLocalCache);
            } else {

                query = query.using(breeze.FetchStrategy.FromServer);
            }

            return manager.executeQuery(query.using(service)).then(function (result) {

                return result;
            });
        }

queryParamCache is used as a flag to find out if the query results are already in cache.

Now, if I call this method and set offset to 120 in order to skip the first 12 pages (10 records per page), a call is made to the server and results are displayed.

Then, I make the same call for page 13, which works, and I go back to page 12. This time records are fetched from the cache, which is what I want.

But in breezejs code, in the function executeQueryLocally, the following code is executed:

 var skipCount = query.skipCount;
    if (skipCount) {
        result = result.slice(skipCount);
    }

skipCount is set to 120, but obviously this just deletes everything in the array, since I only had 20 records (page 12 and page 13).

Is this not a bug ? Or did I miss something ?

Jay Traband Jay Traband · Accepted Answer · 2013-06-10T19:19:46

You didn't miss anything, and this is NOT a bug.

It's just that if breeze is executing a local query then all it has to work with is the data in the local query cache. With that constraint, breeze is returning exactly the correct answer. Basically, a local query is simply a query against the local cache, so if the local cache contains 40 records and you tell it to skip 120 and give you the next 10, then no records will be returned.

In general, if you want to use a query with 'skip' against the local cache, then you must understand the restrictions. i.e. either bring all of the data into the cache or remove the 'skip' or insure that the 'to be skipped' records are already in the cache.

breezejs: issue with FetchFromLocalCache strategy when using Skip

1 Answers