This is a followup of my question at How to create a rule to combine the terms of 2 fields to create a new term and store it in a 3rd field?.
How can I prevent that each time a node is viewed, it creates duplicate taxonomy terms, as shown in this example:
Any suggestions?
I'm assuming you're using a rule that looks similar (equal?) to the rule in the accepted answer in that related question, which looks like so:
{ "rules_improved_combination_of_taxonomy_terms" : {
"LABEL" : "Improved combination of taxonomy terms",
"PLUGIN" : "reaction rule",
"OWNER" : "rules",
"REQUIRES" : [ "rules" ],
"ON" : { "node_view--article" : { "bundle" : "article" } },
"DO" : [
{ "drupal_message" : { "message" : "[node:field-a][node:field-b]" } },
{ "variable_add" : {
"USING" : { "type" : "text", "value" : "[node:field-a][node:field-b]" },
"PROVIDE" : { "variable_added" : { "variable_added" : "Added variable" } }
}
},
{ "entity_create" : {
"USING" : {
"type" : "taxonomy_term",
"param_name" : "[variable-added:value]",
"param_vocabulary" : "tags"
},
"PROVIDE" : { "entity_created" : { "entity_created" : "Created entity" } }
}
},
{ "entity_save" : { "data" : [ "entity-created" ], "immediate" : "1" } },
{ "data_set" : { "data" : [ "node:field-c" ], "value" : [ "entity-created" ] } },
{ "entity_save" : { "data" : [ "node:field-c" ], "immediate" : "1" } }
]
}
}
The above rule does not perform any verification if the term [node:field-a][node:field-b] (= the value that gets stored in "field C") already exists. Instead each time the Rules Actions are triggered (ie each time "an Article is viewed"), it unconditionally creates that term (which may already exist) another time. So that is why you get all those duplicate terms (like helloworld in your example).
The solution (fix) for that is that you add some extra logic in your rule to only perform the 3rd (= entity_create) and 4th (= entity_save of the created term) Rules Action so that those 2 Rules Actions are only performed if the term does not exist yet.
There are basically 2 solutions/approaches to implement such exta logic:
The advantage of the first solution is that the entire logic is contained in a single Rule, though (disadvantage) it requires yet another module.
With either of both solutions, you basically improve this rule with something like "If the term for field C does not exist yet, then let's quickly create it now, so that we can use that term as the value for field C".
Easy enough, no? ... All you need to know is how to actually perform a check in Rules to verify "If that term is already contained in the list of terms of your taxonomy".
Below is a possible solution using Conditional Rules. The improved rule looks like so:
{ "rules_combine_taxonomy_terms_without_creating_duplicates" : {
"LABEL" : "Combine taxonomy terms without creating duplicates",
"PLUGIN" : "reaction rule",
"OWNER" : "rules",
"REQUIRES" : [ "rules", "rules_conditional" ],
"ON" : { "node_view--article" : { "bundle" : "article" } },
"DO" : [
{ "drupal_message" : { "message" : "Value of term for field C will be set to: \u003Cstrong\u003E[node:field-a][node:field-b]\u003C\/strong\u003E." } },
{ "variable_add" : {
"USING" : { "type" : "text", "value" : "[node:field-a][node:field-b]" },
"PROVIDE" : { "variable_added" : { "combined_term" : "Combined Term" } }
}
},
{ "entity_query" : {
"USING" : {
"type" : "taxonomy_term",
"property" : "vocabulary",
"value" : [ "node:field-a:vocabulary" ]
},
"PROVIDE" : { "entity_fetched" : { "existing_terms" : "Existing Terms" } }
}
},
{ "variable_add" : {
"USING" : { "type" : "boolean", "value" : "0" },
"PROVIDE" : { "variable_added" : { "new_term_exist" : "New term exists" } }
}
},
{ "LOOP" : {
"USING" : { "list" : [ "existing-terms" ] },
"ITEM" : { "current_term" : "Current term" },
"DO" : [
{ "CONDITIONAL" : [
{
"IF" : { "text_matches" : { "text" : [ "current-term:name" ], "match" : "[combined-term:value]" } },
"DO" : [
{ "data_set" : { "data" : [ "new-term-exist" ], "value" : "1" } },
{ "data_set" : { "data" : [ "node:field-c" ], "value" : [ "current-term" ] } },
{ "drupal_message" : { "message" : "Term \u003Cstrong\u003E[node:field-a][node:field-b]\u003C\/strong\u003E already exists (no need to create it now)." } }
]
}
]
}
]
}
},
{ "CONDITIONAL" : [
{
"IF" : { "data_is" : { "data" : [ "new-term-exist" ], "value" : "0" } },
"DO" : [
{ "entity_create" : {
"USING" : {
"type" : "taxonomy_term",
"param_name" : "[combined-term:value]",
"param_vocabulary" : "tags"
},
"PROVIDE" : { "entity_created" : { "term_created" : "Created term" } }
}
},
{ "entity_save" : { "data" : [ "term-created" ], "immediate" : "1" } },
{ "data_set" : { "data" : [ "node:field-c" ], "value" : [ "term-created" ] } },
{ "drupal_message" : { "message" : "Term \u003Cstrong\u003E[node:field-a][node:field-b]\u003C\/strong\u003E did not yet exist and was created just now." } }
]
}
]
},
{ "entity_save" : { "data" : [ "node:field-c" ], "immediate" : "1" } },
{ "drupal_message" : { "message" : "\u003Cstrong\u003ENote\u003C\/strong\u003E: After updating field A or B, a page refresh is needed to actually SEE a value of field C = \u003Cstrong\u003E[node:field-a][node:field-b]\u003C\/strong\u003E." } }
]
}
}
Even though it's not an obvious rule to digest (I think), it mostly does these things:
entity_query to create a list of existing terms (stored in existing_terms), for the vocabulary used in Field A (as per the node:field-a:vocabulary in that entity_query). So the assumption is that Field A and Field C use the same vocabulary (there are no details about that in the question). If that's not the case, just replace that vocabulary with whatever fits, or maybe just hardcode it.new_term_exist, which verifies if the term to be saved in Field C already exists.However, there is 1 minor detail to be aware of, as detailed in the message of the very last Rules Action ... For anybody interested in addressing that (to make that message obsolete), please post an extra answer and feel free to use this rule here to start from.
Note: even though, in theory, you should also be able to use Rules Components instead of Conditional Rules (refer to the answer to "What's the alternative to using the Conditional Rules module?" for more details on that), the key challenge with that is that you run in a tough-to-debug issue when passing values to such Rules Components, in the cases where the value of Field C is still blank (eg when creating a new node).
PS: Q: How do you eat an elephant? A: 1 bite at a time ... (though there is only 1 bite left of it now).
I think the Rules condition, URL Alias Exists is perfect for this scenario if put into two rules, one for yes and one for no. Taxonomy terms will have an alias once created so it's easy to check if /taxonomy_vocabulary/[A][B] exists before doing anything with C.
When the node is created or updated, the rules check for A and B added together to see if that AB taxonomy term already exists since every taxonomy term has an alias. If it already exists (yes), the rule fetches it and uses it and if not (no), it creates it.
For example, the first time a node is created or updated with A: New and B: York, "/cities/newyork" wouldn't exist so we create it. The next time we use A: New and B: York, the rule finds the existing term and fetches it.
The below assumes a single-language taxonomy vocabulary. The nodes can be multi-lingual.
PSUEDO-RULES
Rule 1 - Taxonomy C exists
Events: Node is saved / Node is updated
Condition: URL Alias Exists > Use replacement patterns to join A and B in Value field
eg. taxonomy/[a][b]
Action: Create variable > [a][b]
Action: Fetch Entity by Property > Taxonomy Term > Name > Created Variable
Action: Set Data Value > C: Fetched Entity:0
Rule 2 - Taxonomy C doesn't exist yet
Events: Node is saved / Node is updated
Condition: NOT URL Alias Exists > Use replacement patterns to join A and B in Value field
Action: Create entity > Taxonomy Term > "AB" using replacement patterns
(not the drop-down list!)
Action: Set Data Value > C: Created Entity
Rules exports
To test these rules, you'll need a Drupal install with Articles, Tags and no Pathauto messing with the urls.
Add three term reference fields to Article for the Tags Vocabulary.
Machine Names
field_tax_tags_a
field_tax_tags_b
field_tax_tags_c
Rule 1 - AB Term exists so fetch it
{ "rules_exists" : {
"LABEL" : "Exists",
"PLUGIN" : "reaction rule",
"OWNER" : "rules",
"REQUIRES" : [ "rules", "path" ],
"ON" : {
"node_insert--article" : { "bundle" : "article" },
"node_update--article" : { "bundle" : "article" }
},
"IF" : [
{ "path_alias_exists" : { "alias" : "tags\/[node:field-tax-tags-a][node:field-tax-tags-b]" } }
],
"DO" : [
{ "variable_add" : {
"USING" : {
"type" : "text",
"value" : "[node:field-tax-tags-a][node:field-tax-tags-b]"
},
"PROVIDE" : { "variable_added" : { "variable_added" : "Added variable" } }
}
},
{ "entity_query" : {
"USING" : {
"type" : "taxonomy_term",
"property" : "name",
"value" : [ "variable-added" ],
"limit" : "1"
},
"PROVIDE" : { "entity_fetched" : { "entity_fetched" : "Fetched entity" } }
}
},
{ "data_set" : { "data" : [ "node:field-tax-tags-c" ], "value" : [ "entity-fetched:0" ] } }
]
}
}
Rule 2 - AB Term doesn't exist so create it
{ "rules_doesn_t_exist" : {
"LABEL" : "Doesn\u0027t exist",
"PLUGIN" : "reaction rule",
"OWNER" : "rules",
"REQUIRES" : [ "rules", "path" ],
"ON" : {
"node_insert--article" : { "bundle" : "article" },
"node_update--article" : { "bundle" : "article" }
},
"IF" : [
{ "NOT path_alias_exists" : { "alias" : "tags\/[node:field-tax-tags-a][node:field-tax-tags-b]" } }
],
"DO" : [
{ "entity_create" : {
"USING" : {
"type" : "taxonomy_term",
"param_name" : "[node:field-tax-tags-a][node:field-tax-tags-b]",
"param_vocabulary" : "tags"
},
"PROVIDE" : { "entity_created" : { "entity_created" : "Created entity" } }
}
},
{ "data_set" : { "data" : [ "node:field-tax-tags-c" ], "value" : [ "entity-created" ] } }
]
}
}
After that, create and edit some articles only using A and B. C matches and instead of duplicating, will fetch the existing term.
