// Build a restriction from the two dates in the console
var restriction = new Ab.view.Restriction();
restriction.addClause('wr.date_requested', form.date_requested.from, '>=');
restriction.addClause('wr.date_requested', form.date_requested.to, '<=');

// Get all of the work request records within the restriction
var wrRecords = View.dataSources.get('wrDS').getRecords(restriction);

var blDS = View.dataSources.get('blDS');

// Loop over each record
for (var i = 0; i < wrRecords.length; i++) {
    var wrRec = wrRecords[i];

    // Do stuff with wrRec here

    // Build a restriction from the bl_id in each work request record
    var blId = wrRec.getValue('wr.bl_id');
    var blRes = new Ab.view.Restriction();
    blRes.addClause('bl.bl_id', blId);

    // Get all of the building records with that bl_id
    // NOTE: OBVIOUSLY, THIS IS DUMB AND CONTRIVED.
    // (Honestly, I can't remember right now if you need to do
    // blDS.clearRestrictions() :shrug:)
    var blRecords = blDS.getRecords(blRes);

    // Loop over each building record
    for (var j = 0; j < blRecords.length; j++) {
        var blRec = blRecords[j];

        // Do work here
    }
}

// Initially just as above
var restriction = new Ab.view.Restriction();
restriction.addClause('wr.date_requested', form.date_requested.from, '>=');
restriction.addClause('wr.date_requested', form.date_requested.to, '<=');

var wrRecords = View.dataSources.get('wrDS').getRecords(restriction);

// Here, we loop over the retrieved wr records and grab just the bl_id.
var blIds = wrRecords.map(function(rec) {
    return rec.getValue('wr.bl_id');
});

// Restriction.addClause can take in an array, and will "correctly" format the
// elements for the datasource field, wrapping the whole thing in `()`. If you
// don't trust Archibus to handle that correctly, a simple
//     var blIdRes = "('" + blIds.join("', '") + "')";
// will do in a pinch (tho this fucks up if the values you're concating have
// apostrophies in them, lol)

// Also note that this doesn't have to be the only restriction you pass in. If
// necessary, pass in any number of restrictions to this bottom-level dataSource,
// to further refine your search.
var blIdRes = new Ab.view.Restriction();
blIdRes.addClause('bl.bl_id', blIds, 'IN');

// Here we get all records from the bottom-level dataSource that fall under the
// combination of both restrictions. They come back in a potentially massive array
// of DataRecords, which is fine because the trip to the database is the actual
// source of the slow downs.
var tempRecords = View.dataSources.get('blDS').getRecords(blIdRes);

// One issue I've not mentioned yet is that these records will come back in *an*
// order, but without any information related to the totals of each subquery or any
// easy way to select within each having already fetched them. To solve this, we
// construct a plain javascript object (a dictionary) and use the different
// subquery elements (those individual items in the blIds array above) to act as
// the key to an array of the records from the bottom-level query.
var allBlRecords = {};
tempRecords.forEach(function(record, idx) {
    var key = record.getValue('wr.bl_id');
    if (key in allBlRecords) {
        allBlRecords[key].push(record);
    } else {
        allBlRecords[key] = [record];
    }
});

// Now we can enter our actual work for-loop, but this time with all information
// we need generated up front.
for (var i = 0; i < wrRecords.length; i++) {
    var wrRec = wrRecords[i];

    // Do stuff with wrRec here like before, but really cool stuff this time.

    // Notice here that all we're doing is retreiving an array of records from
    // a plain javascript object. This is an incredibly fast operation for any
    // browser (even IE 9 handles this faster than a database hit).
    var blRecords = allBlRecords[wrRec.getValue('wr.bl_id')];

    // Loop over each building record
    for (var j = 0; j < blRecords.length; j++) {
        var blRec = blRecords[j];

        // Do work here
    }
}