Everlive Filtering Query with Optional Multiple Conditions

[David Weinberg]

Hi,

Sorry if this has been asked before, I did try searching first but didn't find anything.

I am creating a filter for a list screen. The contains a number of fields, currently 7, that the user may or may not assign a value too. For each filter field given a value, the data should be filtered to only show the matching records.

The app is NativeScript Angular . I tried the code below but only one where() is respected. I need to chain more than one together as an AND. I see in the docs the syntax for this is to do filter.where().eq("Field1", "Value1").eq("Field2", "Value2")... but how do I best do this in the case where I need Field 1, 3 and 5 without creating very verbose code to cover every combination of the 7.

getFilter () {

    let filter = this._provider.newQuery;

    if (this._priorityFilter) {
        filter.where().eq("Priority", this._priorityFilter);
    }
    if (this._jobTypeFilter) {
        filter.where().eq("JobType", this._jobTypeFilter);
    }
    if (this._statusFilter) {
        filter.where().eq("Status", this._statusFilter);
    }
    if (this._referredToFilter) {
        filter.where().eq("ReferredTo", this._referredToFilter);
    }

    return filter;

}

 

Thanks in advance,

David

[Martin]

Hi David,

When constructing the Everlive query, once you end the method chaining (by adding a semicolon ";") you would not be able to add additional clauses to the same where().and().eq() filter so it is normal that only one where().eq() clause is respected.

When executing the request, the Everlive Query would construct a JSON object and add it as a filter to the request. In your use case when you want to add multiple filters based on conditions, it would be better to construct this JSON object filter yourself and pass it to the request as a filter. The code would look like this:

var el = new Everlive('your-app-id');
var data = el.data('collection-name-here');

var filter = {};

if (this._priorityFilter) {
    filter.Priority = this._priorityFilter;
}
if (this._jobTypeFilter) {
    filter.JobType = this._jobTypeFilter;
}
if (this._statusFilter) {
    filter.Status = this._statusFilter;
}
if (this._referredToFilter) {
    filter.ReferredTo = this._referredToFilter;
}

data.get(filter)
    .then(data => console.log(data))
    .catch(error => console.log(data));

The created filter is a JSON object like this (all key-value pairs are looked as if they were in an AND clause):

{
    "Priority": "_priorityFilter-value",
    "JobType": "_jobTypeFilter-value",
    "Status": "_statusFilter-value",
    "ReferredTo": "_referredToFilter-value"
}

If you would like to create a more sophisticated filter (using or() and different than eq() expressions), please refer to the documentation here. For instance, the same results as the above could also be assembled like this:

var el = new Everlive('your-app-id');
var data = el.data('collection-name-here');

var filter = { "$and": [] };

if (this._priorityFilter) {
    filter["$and"].push({ "Priority": { "$eq": this._priorityFilter } });
}
if (this._jobTypeFilter) {
    filter["$and"].push({ "JobType": { "$eq": this._jobTypeFilter } });
}
if (this._statusFilter) {
    filter["$and"].push({ "Status": { "$eq": this._statusFilter } });
}
if (this._referredToFilter) {
    filter["$and"].push({ "ReferredTo": { "$eq": this._referredToFilter } });
}

data.get(filter)
    .then(data => console.log(data))
    .catch(error => console.log(data));

The created filter would look like this:

{
    "$and": [
        { "Priority": { "$eq": "_priorityFilter-value" } },
        { "JobType": { "$eq": "_jobTypeFilter-value" } },
        { "Status": { "$eq": "_statusFilter-value" } },
        { "ReferredTo": { "$eq": "_referredToFilter-value" } }
    ]
}

Let me know if this has helped.

Regards,
Martin
Progress Telerik

 

 

[David Weinberg]

Hi Martin,

Thanks, that is working perfectly. 

David