Problem with condition types in the Magento 2 REST API

Question

I'm trying to use the REST API in Magento 2 to get orders created after a certain date. But it seems as though everytime I try to use any condition other than "eq", it fails with the following error message:

{
    "message": "Notice: Array to string conversion in /var/www/html/magento/vendor/magento/framework/Reflection/TypeCaster.php on line 34",
    "trace": "#0 /var/www/html/magento/vendor/magento/framework/Reflection/TypeCaster.php(34): Magento\\Framework\\App\\ErrorHandler->handler(8, 'Array to string...', '/var/www/html/m...', 34, Array)\n#1 /var/www/html/magento/vendor/magento/framework/Reflection/DataObjectProcessor.php(115): Magento\\Framework\\Reflection\\TypeCaster->castValueToType(Array, 'string')\n#2 /var/www/html/magento/vendor/magento/framework/Reflection/DataObjectProcessor.php(107): Magento\\Framework\\Reflection\\DataObjectProcessor->buildOutputDataArray(Object(Magento\\Sales\\Model\\Order\\Payment), '\\Magento\\Sales\\...')\n#3 /var/www/html/magento/vendor/magento/framework/Reflection/DataObjectProcessor.php(113): Magento\\Framework\\Reflection\\DataObjectProcessor->buildOutputDataArray(Object(Magento\\Sales\\Model\\Order), '\\Magento\\Sales\\...')\n#4 /var/www/html/magento/vendor/magento/framework/Webapi/ServiceOutputProcessor.php(107): Magento\\Framework\\Reflection\\DataObjectProcessor->buildOutputDataArray(Object(Magento\\Sales\\Model\\ResourceModel\\Order\\Collection), '\\Magento\\Sales\\...')\n#5 /var/www/html/magento/vendor/magento/framework/Webapi/ServiceOutputProcessor.php(59): Magento\\Framework\\Webapi\\ServiceOutputProcessor->convertValue(Object(Magento\\Sales\\Model\\ResourceModel\\Order\\Collection), '\\Magento\\Sales\\...')\n#6 /var/www/html/magento/vendor/magento/module-webapi/Controller/Rest.php(270): Magento\\Framework\\Webapi\\ServiceOutputProcessor->process(Object(Magento\\Sales\\Model\\ResourceModel\\Order\\Collection), 'Magento\\Sales\\A...', 'getList')\n#7 /var/www/html/magento/vendor/magento/module-webapi/Controller/Rest.php(160): Magento\\Webapi\\Controller\\Rest->processApiRequest()\n#8 /var/www/html/magento/var/generation/Magento/Webapi/Controller/Rest/Interceptor.php(24): Magento\\Webapi\\Controller\\Rest->dispatch(Object(Magento\\Framework\\App\\Request\\Http))\n#9 /var/www/html/magento/vendor/magento/framework/App/Http.php(115): Magento\\Webapi\\Controller\\Rest\\Interceptor->dispatch(Object(Magento\\Framework\\App\\Request\\Http))\n#10 /var/www/html/magento/vendor/magento/framework/App/Bootstrap.php(258): Magento\\Framework\\App\\Http->launch()\n#11 /var/www/html/magento/index.php(39): Magento\\Framework\\App\\Bootstrap->run(Object(Magento\\Framework\\App\\Http))\n#12 {main}"
}

And I've tried to do other conditions and fields, like getting every order with a grand_total greater than 100 (i.e. "gt" and "100") but that fails with the same error message. If I do a regular "eq" condition type, then it works.

Can anyone help me understand what I'm doing wrong? Let me know if I need to clarify my question with more examples or something.

Edit: It seems whenever the order API returns more than one item, this error occurs.

Edit 2: This is the request I'm trying to make: /rest/V1/orders?searchCriteria%5Bfilter_groups%5D%5B0%5D%5Bfilters%5D%5B0%5D%5Bfield%5D=grand_total&searchCriteria%5Bfilter_groups%5D%5B0%5D%5Bfilters%5D%5B0%5D%5Bvalue%5D=80&searchCriteria%5Bfilter_groups%5D%5B0%5D%5Bfilters%5D%5B0%5D%5Bcondition_type%5D=gt&searchCriteria%5Bfilter_groups%5D%5B0%5D%5Bfilters%5D%5B1%5D%5Bfield%5D=grand_total&searchCriteria%5Bfilter_groups%5D%5B0%5D%5Bfilters%5D%5B1%5D%5Bvalue%5D=90&searchCriteria%5Bfilter_groups%5D%5B0%5D%5Bfilters%5D%5B1%5D%5Bcondition_type%5D=lt. It's the built in REST interface, so nothing custom built. To add some context, if I do the exact same request against the invoices endpoint instead, I get the correct results (though invoices instead of orders, naturally).

Answer 1

Probably you are treating an array as a string. Could you paste here the piece of code where you are trying to call the API and working with the results?

Answer 2

I tried your request to the Orders API (changing only the interval of grant_total field) and it worked for me:

with:

http://miomagento.it/rest/V1/orders?searchCriteria[filter_groups][0][filters][0][field]=grand_total&searchCriteria[filter_groups][0][filters][0][value]=10&searchCriteria[filter_groups][0][filters][0][condition_type]=gt&searchCriteria[filter_groups][0][filters][1][field]=grand_total&searchCriteria[filter_groups][0][filters][1][value]=400&searchCriteria[filter_groups][0][filters][1][condition_type]=lt

I got:

<response>
<items>
<item>
<base_currency_code>EUR</base_currency_code>
<base_discount_amount>0</base_discount_amount>
<base_grand_total>15</base_grand_total>
<base_discount_tax_compensation_amount>0</base_discount_tax_compensation_amount>
<base_discount_tax_compensation_invoiced/>
<base_discount_tax_compensation_refunded/>
<base_shipping_amount>5</base_shipping_amount>
<base_shipping_discount_amount>0</base_shipping_discount_amount>
<base_shipping_discount_tax_compensation_amnt/>
<base_shipping_incl_tax>5</base_shipping_incl_tax>
<base_shipping_tax_amount>0</base_shipping_tax_amount>
<base_subtotal>10</base_subtotal>
<base_subtotal_incl_tax>10</base_subtotal_incl_tax>
<base_tax_amount>0</base_tax_amount>
<base_total_due>15</base_total_due>
<base_to_global_rate>1</base_to_global_rate>
<base_to_order_rate>1</base_to_order_rate>
<billing_address_id>2</billing_address_id>
<created_at>2016-05-22 17:22:18</created_at>
<customer_email>[email protected]</customer_email>
<customer_firstname>xxx</customer_firstname>
<customer_group_id>1</customer_group_id>
<customer_id>1</customer_id>
<customer_is_guest>0</customer_is_guest>
<customer_lastname>xxx</customer_lastname>
<customer_note_notify>1</customer_note_notify>
<discount_amount>0</discount_amount>
<email_sent>1</email_sent>
<entity_id>1</entity_id>
<global_currency_code>EUR</global_currency_code>
<grand_total>15</grand_total>
<discount_tax_compensation_amount>0</discount_tax_compensation_amount>
<discount_tax_compensation_invoiced/>
<discount_tax_compensation_refunded/>
<increment_id>000000001</increment_id>
<is_virtual>0</is_virtual>
<order_currency_code>EUR</order_currency_code>
<protect_code>880c63</protect_code>
<quote_id>1</quote_id>
<remote_ip>192.168.1.30</remote_ip>
<shipping_amount>5</shipping_amount>
<shipping_description>Flat Rate - Fixed</shipping_description>
<shipping_discount_amount>0</shipping_discount_amount>
<shipping_discount_tax_compensation_amount>0</shipping_discount_tax_compensation_amount>
<shipping_incl_tax>5</shipping_incl_tax>
<shipping_tax_amount>0</shipping_tax_amount>
<state>new</state>
<status>pending</status>
<store_currency_code>EUR</store_currency_code>
<store_id>1</store_id>
<store_name>Main Website Main Website Store</store_name>
<store_to_base_rate>0</store_to_base_rate>
<store_to_order_rate>0</store_to_order_rate>
<subtotal>10</subtotal>
<subtotal_incl_tax>10</subtotal_incl_tax>
<tax_amount>0</tax_amount>
<total_due>15</total_due>
<total_item_count>1</total_item_count>
<total_qty_ordered>1</total_qty_ordered>
<updated_at>2016-05-22 17:22:20</updated_at>
<weight>7</weight>
<items>
<item>
<amount_refunded>0</amount_refunded>
<base_amount_refunded>0</base_amount_refunded>
<base_discount_amount>0</base_discount_amount>
<base_discount_invoiced>0</base_discount_invoiced>
<base_discount_tax_compensation_amount>0</base_discount_tax_compensation_amount>
<base_discount_tax_compensation_invoiced/>
<base_discount_tax_compensation_refunded/>
<base_original_price>10</base_original_price>
<base_price>10</base_price>
<base_price_incl_tax>10</base_price_incl_tax>
<base_row_invoiced>0</base_row_invoiced>
<base_row_total>10</base_row_total>
<base_row_total_incl_tax>10</base_row_total_incl_tax>
<base_tax_amount>0</base_tax_amount>
<base_tax_invoiced>0</base_tax_invoiced>
<created_at>2016-05-22 17:22:18</created_at>
<discount_amount>0</discount_amount>
<discount_invoiced>0</discount_invoiced>
<discount_percent>0</discount_percent>
<free_shipping>0</free_shipping>
<discount_tax_compensation_amount>0</discount_tax_compensation_amount>
<discount_tax_compensation_canceled/>
<discount_tax_compensation_invoiced/>
<discount_tax_compensation_refunded/>
<is_qty_decimal>0</is_qty_decimal>
<is_virtual>0</is_virtual>
<item_id>1</item_id>
<name>Sedia</name>
<no_discount>0</no_discount>
<order_id>1</order_id>
<original_price>10</original_price>
<price>10</price>
<price_incl_tax>10</price_incl_tax>
<product_id>1</product_id>
<product_type>simple</product_type>
<qty_canceled>0</qty_canceled>
<qty_invoiced>0</qty_invoiced>
<qty_ordered>1</qty_ordered>
<qty_refunded>0</qty_refunded>
<qty_shipped>0</qty_shipped>
<quote_item_id>1</quote_item_id>
<row_invoiced>0</row_invoiced>
<row_total>10</row_total>
<row_total_incl_tax>10</row_total_incl_tax>
<row_weight>7</row_weight>
<sku>Sedia</sku>
<store_id>1</store_id>
<tax_amount>0</tax_amount>
<tax_invoiced>0</tax_invoiced>
<tax_percent>0</tax_percent>
<updated_at>2016-05-22 17:22:18</updated_at>
<weight>7</weight>
</item>
</items>
<billing_address>
<address_type>billing</address_type>
<city>catania</city>
<country_id>IT</country_id>
<email>[email protected]</email>
<entity_id>2</entity_id>
<firstname>xxx</firstname>
<lastname>xxx</lastname>
<parent_id>1</parent_id>
<postcode>95100</postcode>
<street>
<item>via prova</item>
</street>
<telephone>095378244</telephone>
</billing_address>
<payment>
<account_status/>
<additional_information>
<item>Check / Money order</item>
<item/>
<item/>
</additional_information>
<amount_ordered>15</amount_ordered>
<base_amount_ordered>15</base_amount_ordered>
<base_shipping_amount>5</base_shipping_amount>
<cc_last4/>
<entity_id>1</entity_id>
<method>checkmo</method>
<parent_id>1</parent_id>
<shipping_amount>5</shipping_amount>
</payment>
<status_histories/>
<extension_attributes>
<shipping_assignments>
<item>
<shipping>
<address>
<address_type>shipping</address_type>
<city>catania</city>
<country_id>IT</country_id>
<customer_address_id>1</customer_address_id>
<email>[email protected]</email>
<entity_id>3</entity_id>
<firstname>xxx</firstname>
<lastname>xxx</lastname>
<parent_id>2</parent_id>
<postcode>95100</postcode>
<street>
<item>via prova</item>
</street>
<telephone>095378244</telephone>
</address>
<method>flatrate_flatrate</method>
<total>
<base_shipping_amount>100</base_shipping_amount>
<base_shipping_discount_amount>0</base_shipping_discount_amount>
<base_shipping_discount_tax_compensation_amnt/>
<base_shipping_incl_tax>100</base_shipping_incl_tax>
<base_shipping_tax_amount>0</base_shipping_tax_amount>
<shipping_amount>100</shipping_amount>
<shipping_discount_amount>0</shipping_discount_amount>
<shipping_discount_tax_compensation_amount>0</shipping_discount_tax_compensation_amount>
<shipping_incl_tax>100</shipping_incl_tax>
<shipping_tax_amount>0</shipping_tax_amount>
</total>
</shipping>
<items>
<item>
<amount_refunded>0</amount_refunded>
<base_amount_refunded>0</base_amount_refunded>
<base_discount_amount>0</base_discount_amount>
<base_discount_invoiced>0</base_discount_invoiced>
<base_discount_tax_compensation_amount>0</base_discount_tax_compensation_amount>
<base_discount_tax_compensation_invoiced/>
<base_discount_tax_compensation_refunded/>
<base_original_price>10</base_original_price>
<base_price>10</base_price>
<base_price_incl_tax>10</base_price_incl_tax>
<base_row_invoiced>0</base_row_invoiced>
<base_row_total>200</base_row_total>
<base_row_total_incl_tax>200</base_row_total_incl_tax>
<base_tax_amount>0</base_tax_amount>
<base_tax_invoiced>0</base_tax_invoiced>
<created_at>2016-05-22 17:32:09</created_at>
<discount_amount>0</discount_amount>
<discount_invoiced>0</discount_invoiced>
<discount_percent>0</discount_percent>
<free_shipping>0</free_shipping>
<discount_tax_compensation_amount>0</discount_tax_compensation_amount>
<discount_tax_compensation_canceled/>
<discount_tax_compensation_invoiced/>
<discount_tax_compensation_refunded/>
<is_qty_decimal>0</is_qty_decimal>
<is_virtual>0</is_virtual>
<item_id>2</item_id>
<name>Sedia</name>
<no_discount>0</no_discount>
<order_id>2</order_id>
<original_price>10</original_price>
<price>10</price>
<price_incl_tax>10</price_incl_tax>
<product_id>1</product_id>
<product_type>simple</product_type>
<qty_canceled>0</qty_canceled>
<qty_invoiced>0</qty_invoiced>
<qty_ordered>20</qty_ordered>
<qty_refunded>0</qty_refunded>
<qty_shipped>0</qty_shipped>
<quote_item_id>3</quote_item_id>
<row_invoiced>0</row_invoiced>
<row_total>200</row_total>
<row_total_incl_tax>200</row_total_incl_tax>
<row_weight>140</row_weight>
<sku>Sedia</sku>
<store_id>1</store_id>
<tax_amount>0</tax_amount>
<tax_invoiced>0</tax_invoiced>
<tax_percent>0</tax_percent>
<updated_at>2016-05-22 17:32:09</updated_at>
<weight>7</weight>
</item>
</items>
</item>
</shipping_assignments>
</extension_attributes>
</item>
<item>
<base_currency_code>EUR</base_currency_code>
<base_discount_amount>0</base_discount_amount>
<base_grand_total>300</base_grand_total>
<base_discount_tax_compensation_amount>0</base_discount_tax_compensation_amount>
<base_discount_tax_compensation_invoiced/>
<base_discount_tax_compensation_refunded/>
<base_shipping_amount>100</base_shipping_amount>
<base_shipping_discount_amount>0</base_shipping_discount_amount>
<base_shipping_discount_tax_compensation_amnt/>
<base_shipping_incl_tax>100</base_shipping_incl_tax>
<base_shipping_tax_amount>0</base_shipping_tax_amount>
<base_subtotal>200</base_subtotal>
<base_subtotal_incl_tax>200</base_subtotal_incl_tax>
<base_tax_amount>0</base_tax_amount>
<base_total_due>300</base_total_due>
<base_to_global_rate>1</base_to_global_rate>
<base_to_order_rate>1</base_to_order_rate>
<billing_address_id>4</billing_address_id>
<created_at>2016-05-22 17:32:09</created_at>
<customer_email>[email protected]</customer_email>
<customer_firstname>xxx</customer_firstname>
<customer_gender>0</customer_gender>
<customer_group_id>1</customer_group_id>
<customer_id>1</customer_id>
<customer_is_guest>0</customer_is_guest>
<customer_lastname>xxxx</customer_lastname>
<customer_note_notify>1</customer_note_notify>
<discount_amount>0</discount_amount>
<email_sent>1</email_sent>
<entity_id>2</entity_id>
<global_currency_code>EUR</global_currency_code>
<grand_total>300</grand_total>
<discount_tax_compensation_amount>0</discount_tax_compensation_amount>
<discount_tax_compensation_invoiced/>
<discount_tax_compensation_refunded/>
<increment_id>000000002</increment_id>
<is_virtual>0</is_virtual>
<order_currency_code>EUR</order_currency_code>
<protect_code>80fc50</protect_code>
<quote_id>3</quote_id>
<shipping_amount>100</shipping_amount>
<shipping_description>Flat Rate - Fixed</shipping_description>
<shipping_discount_amount>0</shipping_discount_amount>
<shipping_discount_tax_compensation_amount>0</shipping_discount_tax_compensation_amount>
<shipping_incl_tax>100</shipping_incl_tax>
<shipping_tax_amount>0</shipping_tax_amount>
<state>new</state>
<status>pending</status>
<store_currency_code>EUR</store_currency_code>
<store_id>1</store_id>
<store_name>Main Website Main Website Store</store_name>
<store_to_base_rate>0</store_to_base_rate>
<store_to_order_rate>0</store_to_order_rate>
<subtotal>200</subtotal>
<subtotal_incl_tax>200</subtotal_incl_tax>
<tax_amount>0</tax_amount>
<total_due>300</total_due>
<total_item_count>1</total_item_count>
<total_qty_ordered>20</total_qty_ordered>
<updated_at>2016-05-22 17:32:12</updated_at>
<weight>140</weight>
<items>
<item>
<amount_refunded>0</amount_refunded>
<base_amount_refunded>0</base_amount_refunded>
<base_discount_amount>0</base_discount_amount>
<base_discount_invoiced>0</base_discount_invoiced>
<base_discount_tax_compensation_amount>0</base_discount_tax_compensation_amount>
<base_discount_tax_compensation_invoiced/>
<base_discount_tax_compensation_refunded/>
<base_original_price>10</base_original_price>
<base_price>10</base_price>
<base_price_incl_tax>10</base_price_incl_tax>
<base_row_invoiced>0</base_row_invoiced>
<base_row_total>200</base_row_total>
<base_row_total_incl_tax>200</base_row_total_incl_tax>
<base_tax_amount>0</base_tax_amount>
<base_tax_invoiced>0</base_tax_invoiced>
<created_at>2016-05-22 17:32:09</created_at>
<discount_amount>0</discount_amount>
<discount_invoiced>0</discount_invoiced>
<discount_percent>0</discount_percent>
<free_shipping>0</free_shipping>
<discount_tax_compensation_amount>0</discount_tax_compensation_amount>
<discount_tax_compensation_canceled/>
<discount_tax_compensation_invoiced/>
<discount_tax_compensation_refunded/>
<is_qty_decimal>0</is_qty_decimal>
<is_virtual>0</is_virtual>
<item_id>2</item_id>
<name>Sedia</name>
<no_discount>0</no_discount>
<order_id>2</order_id>
<original_price>10</original_price>
<price>10</price>
<price_incl_tax>10</price_incl_tax>
<product_id>1</product_id>
<product_type>simple</product_type>
<qty_canceled>0</qty_canceled>
<qty_invoiced>0</qty_invoiced>
<qty_ordered>20</qty_ordered>
<qty_refunded>0</qty_refunded>
<qty_shipped>0</qty_shipped>
<quote_item_id>3</quote_item_id>
<row_invoiced>0</row_invoiced>
<row_total>200</row_total>
<row_total_incl_tax>200</row_total_incl_tax>
<row_weight>140</row_weight>
<sku>Sedia</sku>
<store_id>1</store_id>
<tax_amount>0</tax_amount>
<tax_invoiced>0</tax_invoiced>
<tax_percent>0</tax_percent>
<updated_at>2016-05-22 17:32:09</updated_at>
<weight>7</weight>
</item>
</items>
<billing_address>
<address_type>billing</address_type>
<city>catania</city>
<country_id>IT</country_id>
<customer_address_id>1</customer_address_id>
<email>[email protected]</email>
<entity_id>4</entity_id>
<firstname>xxx</firstname>
<lastname>xxx</lastname>
<parent_id>2</parent_id>
<postcode>95100</postcode>
<street>
<item>via prova</item>
</street>
<telephone>095378244</telephone>
</billing_address>
<payment>
<account_status/>
<additional_information>
<item>Check / Money order</item>
<item/>
<item/>
</additional_information>
<amount_ordered>300</amount_ordered>
<base_amount_ordered>300</base_amount_ordered>
<base_shipping_amount>100</base_shipping_amount>
<cc_exp_year>0</cc_exp_year>
<cc_last4/>
<cc_ss_start_month>0</cc_ss_start_month>
<cc_ss_start_year>0</cc_ss_start_year>
<entity_id>2</entity_id>
<method>checkmo</method>
<parent_id>2</parent_id>
<shipping_amount>100</shipping_amount>
</payment>
<status_histories/>
<extension_attributes>
<shipping_assignments>
<item>
<shipping>
<address>
<address_type>shipping</address_type>
<city>catania</city>
<country_id>IT</country_id>
<customer_address_id>1</customer_address_id>
<email>[email protected]</email>
<entity_id>3</entity_id>
<firstname>xxx</firstname>
<lastname>xxx</lastname>
<parent_id>2</parent_id>
<postcode>95100</postcode>
<street>
<item>via prova</item>
</street>
<telephone>095378244</telephone>
</address>
<method>flatrate_flatrate</method>
<total>
<base_shipping_amount>100</base_shipping_amount>
<base_shipping_discount_amount>0</base_shipping_discount_amount>
<base_shipping_discount_tax_compensation_amnt/>
<base_shipping_incl_tax>100</base_shipping_incl_tax>
<base_shipping_tax_amount>0</base_shipping_tax_amount>
<shipping_amount>100</shipping_amount>
<shipping_discount_amount>0</shipping_discount_amount>
<shipping_discount_tax_compensation_amount>0</shipping_discount_tax_compensation_amount>
<shipping_incl_tax>100</shipping_incl_tax>
<shipping_tax_amount>0</shipping_tax_amount>
</total>
</shipping>
<items>
<item>
<amount_refunded>0</amount_refunded>
<base_amount_refunded>0</base_amount_refunded>
<base_discount_amount>0</base_discount_amount>
<base_discount_invoiced>0</base_discount_invoiced>
<base_discount_tax_compensation_amount>0</base_discount_tax_compensation_amount>
<base_discount_tax_compensation_invoiced/>
<base_discount_tax_compensation_refunded/>
<base_original_price>10</base_original_price>
<base_price>10</base_price>
<base_price_incl_tax>10</base_price_incl_tax>
<base_row_invoiced>0</base_row_invoiced>
<base_row_total>200</base_row_total>
<base_row_total_incl_tax>200</base_row_total_incl_tax>
<base_tax_amount>0</base_tax_amount>
<base_tax_invoiced>0</base_tax_invoiced>
<created_at>2016-05-22 17:32:09</created_at>
<discount_amount>0</discount_amount>
<discount_invoiced>0</discount_invoiced>
<discount_percent>0</discount_percent>
<free_shipping>0</free_shipping>
<discount_tax_compensation_amount>0</discount_tax_compensation_amount>
<discount_tax_compensation_canceled/>
<discount_tax_compensation_invoiced/>
<discount_tax_compensation_refunded/>
<is_qty_decimal>0</is_qty_decimal>
<is_virtual>0</is_virtual>
<item_id>2</item_id>
<name>Sedia</name>
<no_discount>0</no_discount>
<order_id>2</order_id>
<original_price>10</original_price>
<price>10</price>
<price_incl_tax>10</price_incl_tax>
<product_id>1</product_id>
<product_type>simple</product_type>
<qty_canceled>0</qty_canceled>
<qty_invoiced>0</qty_invoiced>
<qty_ordered>20</qty_ordered>
<qty_refunded>0</qty_refunded>
<qty_shipped>0</qty_shipped>
<quote_item_id>3</quote_item_id>
<row_invoiced>0</row_invoiced>
<row_total>200</row_total>
<row_total_incl_tax>200</row_total_incl_tax>
<row_weight>140</row_weight>
<sku>Sedia</sku>
<store_id>1</store_id>
<tax_amount>0</tax_amount>
<tax_invoiced>0</tax_invoiced>
<tax_percent>0</tax_percent>
<updated_at>2016-05-22 17:32:09</updated_at>
<weight>7</weight>
</item>
</items>
</item>
</shipping_assignments>
</extension_attributes>
</item>
</items>
<search_criteria/>
<total_count>2</total_count>
</response>

I tried with magento 2.0.5 clean installation with php 7.0.4. I tried also with more than one customer with orders created and it worked.

Is it possible that you did some fix to core that impact with api? Try to rename vendor folder and redo a clean installation. Otherwise this problem could be somehow generated by data.