CPS-1272 Support for contains in cps-path

we would like to bring support for contains operator in cps-path.

contains() is a method in XPath expression. It is used when the value of any attribute changes dynamically, below are the examples,

Reference

CPS-1272

Issues & decisions

#

Json Data

CPS-PATH Syntax

Output

1

Below is the sample data ,
 Here  are ways  to use contains keyword :

Json data Click here to expand

{
"test:bookstore":{
"bookstore-name": "Chapters",
"categories": [
{
"code": "01",
"name": "SciFi",
"books": [
{
"authors": [
"Iain M. Banks"
],
"lang": "english",
"price": "895",
"pub_year": "1994",
"title": "Feersum Endjinn"
}
]
},
{
"name": "kids",
"code": "02",
"books": [
{
"authors": [
"Philip Pullman"
],
"lang": "Science",
"price": "699",
"pub_year": "1995",
"title": "The Golden Compass"
}
]
}
]
}
}

<cps-path>(contains'[@leafname,'<string-value>']')

Examples

```
//books[contains(@lang,'en')
```
```
//books[contains(@pub_year,'99')
```

Json Response Click here to expand

{
"lang": "en",
"price": 895,
"title": "Feersum Endjinn",
"authors": [
"Iain M. Banks"
],
"pub_year":1994
}
{
"lang": "en",
"price": 699,
"title": "The Golden Compass",
"authors": [
"Philip Pullman"
],
"pub_year":1995
}

Native Query for contains keyword

1.Using LIKE Keyword :

Like operator is used to match specified matching pattern. It has two signs :

% : Matches any sequence of character, the character size may be 0 or more.

_ : Matches any single character.

Query

Output

Decision

1

cpsdb=# SELECT * FROM FRAGMENT WHERE anchor_id = 4 and attributes->>'lang' like '%en%';

Json Response Click here to expand..

{
"lang": "en",
"price": 699,
"title": "The Golden Compass",
"authors": [
"Philip Pullman"
],
"pub_year":1995
}
{
"lang": "english",
"price": 895,
"title": "Feersum Endjinn",
"authors": [
"Iain M. Banks"
],
"pub_year":1994
}

2

cpsdb=# SELECT * FROM FRAGMENT WHERE anchor_id = 4 and attributes->>'lang' ilike '%En%';

Json Response Click here to expand

{
"lang": "en",
"price": 699,
"title": "The Golden Compass",
"authors": [
"Philip Pullman"
],
"pub_year":1995
}
{
"lang": "English",
"price": 895,
"title": "Feersum Endjinn",
"authors": [
"Iain M. Banks"
],
"pub_year":1994
}

27 Mar 2023 As per discussion , with Toine Siebelink Contains Xpath is case sensitive , So ilike keyword would be suitable to implement the contains query which support case sensitive attribute values

3

cpsdb=# SELECT * FROM FRAGMENT WHERE anchor_id = 4 and attributes->>'lang' like 'en';

Json Response Click here to expand

{
"lang": "en",
"price": 699,
"title": "The Golden Compass",
"authors": [
"Philip Pullman"
],
"pub_year":1995
}

2.Using SIMILAR TO Regular Expression Keyword :

The only difference between like and similar to is to pattern matches the given string. It is similar to LIKE, except that it interprets the pattern using the SQL standard's definition of a regular expression

SIMILAR TO supports these pattern-matching metacharacters borrowed from POSIX regular expressions:

| denotes alternation (either of two alternatives).
* denotes repetition of the previous item zero or more times.
+ denotes repetition of the previous item one or more times.
? denotes repetition of the previous item zero or one time.
{m} denotes repetition of the previous item exactly m times.
{m,} denotes repetition of the previous item m or more times.
{m,n} denotes repetition of the previous item at least m and not more than n times.
Parentheses () can be used to group items into a single logical item.
A bracket expression [...] specifies a character class, just as in POSIX regular expressions.

#	Query	Output
1	*cpsdb=# SELECT FROM FRAGMENT WHERE anchor_id = 3 and attributes->>'pub_year'similar to '%(94\|95)%';**	Json Response Click here to expand { "lang": "en", "price": 699, "title": "The Golden Compass", "authors": [ "Philip Pullman" ], "pub_year":1995 } { "lang": "english", "price": 895, "title": "Feersum Endjinn", "authors": [ "Iain M. Banks" ], "pub_year":1994 }

Performance wise : As we are not making much changes for query , the performance is similar to existing query will not effect much