The matches() query matches the data from a JSON file with a given condition (in the form of a regular expression) and returns the results accordingly. It will return a blank value if the condition does not match with the data in the file.

Syntax

The syntax of TinyDB matches() is as follows −

db.search(Query().field.matches(regular expression))

Here, field represents the part of data that we want to access. Query() is the object created of our JSON table named student.

Let”s understand how it works with the help of a couple of examples. We will use the same student database that we have used in all the previous chapters.

Example 1

Let”s see how we can use matches() for full item search.

from tinydb import Query
student = Query()
db.search(student.st_name.matches(''[aZ]*''))

This query will fetch all the rows −

[
   {
      "roll_number":1,
      "st_name":"elen",
      "mark":250,
      "subject":"TinyDB",
      "address":"delhi"
   },
   {
      "roll_number":2,
      "st_name":"Ram",
      "mark":[
         250,
         280
      ],
      "subject":[
         "TinyDB",
         "MySQL"
      ],
      "address":"delhi"
   },
   {
      "roll_number":3,
      "st_name":"kevin",
      "mark":[
         180,
         200
      ],
      "subject":[
         "oracle",
         "sql"
      ],
      "address":"keral"
   },
   {
      "roll_number":4,
      "st_name":"lakan",
      "mark":200,
      "subject":"MySQL",
      "address":"mumbai"
   },
   {
      "roll_number":5,
      "st_name":"karan",
      "mark":275,
      "subject":"TinyDB",
      "address":"benglore"
   }
]

Example 2

Let”s see how we can use matches() for case-sensitive search.

from tinydb import Query
import re
student = Query()
db.search(student.st_name.matches(''ram'', flags=re.IGNORECASE))

This query will fetch the rows where the student name matches the string “ram”. Observe that we have used a flag to ignore the case while matching the strings.

[{
   ''roll_number'': 2,
   ''st_name'': ''Ram'',
   ''mark'': [250, 280],
   ''subject'': [''TinyDB'', ''MySQL''],
   ''address'': ''delhi''
}]

Example 3

Let”s see how we can use matches() for a particular item.

student = Query()
db.search(student.address.matches(''keral''))

This query will fetch the rows where the address matches the string “keral”.

[{''roll_number'': 3, ''st_name'': ''kevin'', ''mark'': [180, 200], ''subject'':
[''oracle'', ''sql''], ''address'': ''keral''}]

Example 4

Let”s see what matches() would return when it does not find a particular item −

student = Query()
db.search(student.address.matches(''Ratlam''))

There are no rows where the “address” field matches the string “Ratlam”, hence it will return a blank value −

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