¶ Using Regular Expressions
¶ Basic Information
Regular expressions are basically used in two main scenarios:
- You get some value in a response JSON node, but before you can write it to the Business Central database, you need to make some changes to the data. (e.g. trim title from the beginning of person name, delete all letters and leave only numbers, etc.).
- You are exporting some field value from Business Central, but you need to make some changes to the data in the final JSON, before sending it to an API service.
Regular expressions are now supported only for the response body. Adding the feature to the request is planned.
Regular expressions are a really strong tool for text manipulation. You can find a basic guideline at https://regexone.com or a nice tool for testing your regular expressions at https://regex101.com.
¶ Response Regular Expression Example
Let's say your API returns the following JSON:
{
"id": 3,
"no": "10000",
"name": "The Cannon Group PLC",
"address": "192 Market Square",
"city": "Birmingham",
"countryCode": "GB",
"phones": []
}
But there's a catch: someone entered Great Britain with the UK country code in your Business Central database and it's not easy to change that now. Of course, if you try to save the GB code into a Customer record and the country does not exist, the operation ends with an error.
Regular expressions to the rescue! Select your operation from the list and open the response body schema. Then select the countryCode node and open the node Details:
Now fill in the regular expression search and replace patterns to following fields:
- Response Regex Pattern – The pattern you are looking for. This one is really simple – you are looking for a
"GB"string – but regular expression patterns can be really complex, too. - If there is a match, it will be replaced with the value of Response Replace Pattern field.
So if in this example the API returns country code US, nothing happens, because there is no match with the search regex pattern. But before RESTwithUS attempts to save the data into Business Central, every GB country code is changed to UK.
Let's have a bit more advanced example. Say you want to get the house number from theaddress node and save it to some variable for further use. In such case select the address node in the response and open the node Details again. Then have a look at Variables tab:
- Variable Name - The name of the variable where you want to save the regular expression output.
- Variable Regex Pattern - Pattern
"^[^\d]*(\d+)[^\d]*$"will save the numbers from the string to a match group – it's this part of expression:"(\d+)"and"\d"is a shorcut for any number. - Variable Replace Pattern - You need to replace the whole string with the first match group that contains the house number, and the syntax for that is
"$1".
After you run the operation, you can check the results in Batch Entries. As you can see, there is a new line with the variable houseNumber and it contains the house number cut from the address:
