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In addition to = operator to check equality, the following logical operators are defined in MongoEngine.
| ne | not equal to |
| lt | less than |
| lte | less than or equal to |
| gt | greater than |
| gte | greater than or equal to |
| not | negate a standard check, may be used before other operators |
| in | value is in list |
| nin | value is not in list |
| mod | value % x == y, where x and y are two provided values |
| all | every item in list of values provided is in array |
| size | the size of the array is |
| exists | value for field exists |
These operators must be attached to field name with double underscore __.
To use greater than (gt) operator, use the following format −
#using greater than operator
for product in products.objects(price__gt=10000):
print (''ID:'',product.ProductID, ''Name:'',product.Name, ''Price:'',product.price)
Output
ID: 1 Name: Laptop Price: 25000 ID: 2 Name: TV Price: 50000 ID: 5 Name: Printer Price: 12500
The in operator is like Python’s in operator. For name of product matching with names in list, the following code is used −
for product in products.objects(Name__in=[''TV'', ''Printer'']):
print (''ID:'',product.ProductID, ''Name:'',product.Name, ''Price:'',product.price)
Output
ID: 2 Name: TV Price: 50000 ID: 5 Name: Printer Price: 12500
You can use following operators as shortcut for regex expressions for applying filter to queries −
| exact | string field exactly matches value |
| iexact | string field exactly matches value (case insensitive) |
| contains | string field contains value |
| icontains | string field contains value (case insensitive) |
| startswith | string field starts with value |
| istartswith | string field starts with value (case insensitive) |
| endswith | string field ends with value |
| iendswith | string field ends with value (case insensitive) |
| match | performs an $elemMatch so you can match an entire document within an array |
For example, the following code prints product details for name containing ‘o’ in name −
for product in products.objects(Name__contains=''o''):
print (''ID:'',product.ProductID, ''Name:'',product.Name, ''Price:'',product.price)
Output
ID: 1 Name: Laptop Price: 25000 ID: 3 Name: Router Price: 2000
In another example of string query, the following code displays name ending with ‘er’−
for product in products.objects(Name__endswith=''er''):
print (''ID:'',product.ProductID, ''Name:'',product.Name, ''Price:'',product.price)
Output
ID: 3 Name: Router Price: 2000 ID: 4 Name: Scanner Price: 5000 ID: 5 Name: Printer Price: 12500
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