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

Native query for Contains Operator using Like Keyword :

#	Issue	Notes	Decisions
1	Which keyword to use ? Do we want case sensitivity or not? Do we follow the Xpath contains or do we become specific?	like %en% ilike %En% like 'en'	27 Mar 2023 As per discussion , with Toine Siebelink , community call like keyword would has consistency which support case sensitive attribute values. Need to discuss with stakeholders. 29 Mar 2023 As per discussion in community call , decided to go with like keyword more consistent support case sensitivity.

#

Json Data

CPS-PATH Syntax

Output

1

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

Json data

{
   "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

{
 "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

1

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

Json Response

{
 "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

{
 "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
}

3

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

Json Response

{
 "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

{
 "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

Implementation of Contains Operator

1.Update antlr parser to recognize this pattern
2.Implement required (native) query
3.Add Integration tests for
a.filter on string leaf-value
b.filter on Integer leaf-value
4.Update documentation
5.demo to team

Limitations

1. contains condition is case sensitive.
2. Only leaves can be used, leaf-list are not supported.
3. Only string and integer values are supported, boolean and float values are not supported.
4. When empty value is passed with contains it returns all the nodes that has given leaf element.