Javascript Filtering on Null Values

Question

I am filtering this list

[
 {
 appLearningItemId: 67
 catalogues: (2) [ {id: 1041, value: "New Catalog"},
                   {id: 1058, value: "Test"}]
 categories: (3) [{id: 1, value: "Soft Skills"},
                  {id: 3, value: "Non-technical"},
                  {id: 5, value: "Induction"}]
 code: "CCE0013"
 suppliers: (3) [{id: 1, value: "Company XYZ Ltd"},
                 {id: 2, value: "test c2"},
                 {id: 17, value: "new company"} ]
 title: "07 Values & Beliefs"
 type: {id: 11377, value: "Elearning"}
 }, ... * 682 items
]

with this object and filter

const filters = {
        type: 'Elearning',
        catalog: 1041,
        category: 1,
        supplier: 1
      }
      let advancedFilteredLearningItems = this.originalLearningItems.filter(obj => obj.type.value == filters.type 
       && obj.catalogues.some( catalogs => catalogs.id == filters.catalog)
       && obj.categories.some( category => category.id == filters.category)
       && obj.suppliers.some(supplier => supplier.id === filters.supplier));
       console.log(advancedFilteredLearningItems)

which works great. Sometimes the filter object will have a null value in some or up to 3 of the values eg:

const filters = {
            type: 'Elearning',
            catalog: null,
            category: 1,
            supplier: null
          }

how do I edit the filter code to not filter on null items so in this case I get back all E-learning items with a category of 1? Currently the filter code is looking for null values but I just want to omit it from the filter completely.

rhavelka · Accepted Answer · 2021-03-03 15:37:24Z

1

Would adding a null check to all of your filters work? So if it is null you return true because you want all of the catalogs before it? This isn't the most efficient solution, but it should get you to where you need.

const filters = {
    type: 'Elearning',
    catalog: 1041,
    category: null,
    supplier: null
}
let advancedFilteredLearningItems = this.originalLearningItems.filter(obj => 
   (filters.type != null ? obj.type.value == filters.type : true)
   && obj.catalogues.some(catalogs => filters.catalog != null ? catalogs.id == filters.catalog : true)
   && obj.categories.some(category => filters.category != null ? category.id == filters.category : true)
   && obj.suppliers.some(supplier => filters.supplier != null ? supplier.id === filters.supplier : true));
console.log(advancedFilteredLearningItems)

EDIT: A more efficient solution is to not loop through your catalogues if there is no filter. This can be done by adding an extra function

let advancedFilteredLearningItems = this.originalLearningItems.filter(obj => 
   (filters.type != null ? obj.type.value == filters.type : true)
   && this.filterItems(filters.catalog, obj.catalogs)
   && this.filterItems(filters.categories, obj.categories)
   && this.filterItems(filters.supplier , obj.suppliers)
console.log(advancedFilteredLearningItems)

// new function
filterItems(filter, array) {
    if (filter == null) {
        return true;
    }
    return array.some(item => item.id == filter);
}

EDIT 2: In case you don't want to add a new function, this should be as efficient as my first edit

let advancedFilteredLearningItems = this.originalLearningItems.filter(obj => 
      (filters.type       == null || obj.type.value == filters.type)
   && (filters.catalog    == null || obj.catalogues.some(catalogs => catalogs.id == filters.catalog))
   && (filters.categories == null || obj.categories.some(category => category.id == filters.category))
   && (filters.supplier   == null || obj.suppliers.some(supplier => supplier.id == filters.supplier))
);

edited Mar 3, 2021 at 15:37

answered Mar 3, 2021 at 15:04

rhavelka

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6 Comments

rhavelka Over a year ago

If the first one didn't work, then I don't think the second one is going to work... I will keep looking into it

rhavelka Over a year ago

@Bwizard I updated my code. I needed some return values in my function

Bwizard Over a year ago

Works perfectly, thank you v.much. If I could double upVote I would!

pilchard Over a year ago

You can replace the ternary operators with ORs (filters.type === null || obj.type.value == filters.type)

rhavelka Over a year ago

@pilchard that is a good point. I updated my second edit to reflect that

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