provider.ts

 getInput(documents, crop_data) {
    let crop = crop_data.crop;
    let inputs = {
      'title': crop,
      'src': this.global.imageUrl+crop_data.src,
      category: []
    };

    let actual_documents = [];
    for (let document of documents) {
      if(document.crops.constructor==Array){
        if (this.global.contains(document.crops, crop)) {
          actual_documents.push(document);
        }
      }
    }

    for (let doc of actual_documents) {
      let category_exists: boolean = false;
      let category_index: string;
      for (let index in inputs.category) {
        if (doc.category === inputs.category[index].name) {
          category_exists = true;
          category_index = index;
        }
      }
      if (category_exists == false) {
        inputs.category.push({
          name: doc.category,
          values: [
            {
              "name": doc.name,
              "src": this.global.imageUrl+doc.photo_url,
              "supplier": doc.supplier,
              "price": doc.price,
              "unit": doc.unit,
              "quantity": doc.quantity,
              "desc":doc.description
            }
          ]
        })
      } else {
        inputs.category[category_index].values.push({
          "name": doc.name,
          "src":this.global.imageUrl+doc.photo_url,
          "supplier": doc.supplier,
          "price": doc.price,
          "unit": doc.unit,
          "quantity": doc.quantity,
          "desc":doc.description
        })
      }
    }

    return inputs;
  }