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Introduce ObjectMapperValueToTree Refaster rule #1938

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Merged
Stephan202 merged 2 commits into from
Nov 15, 2025
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Introduce ObjectMapperValueToTree Refaster rule #1938

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Introduce `ObjectMapperValueToTree` refaster rule
Oct 30, 2025
7ab6dbe
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Stephan202 Oct 31, 2025
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5 changes: 5 additions & 0 deletions error-prone-contrib/pom.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,11 @@
<artifactId>jackson-annotations</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
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@Stephan202 Stephan202 Oct 31, 2025

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We should omit this one from the runtime classpath:

Suggested change
<artifactId>jackson-core</artifactId>
<artifactId>jackson-core</artifactId>
<scope>provided</scope>

<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
Expand Down
18 changes: 18 additions & 0 deletions error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/JacksonRules.java
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Original file line number Diff line number Diff line change
@@ -1,6 +1,8 @@
package tech.picnic.errorprone.refasterrules;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.errorprone.refaster.Refaster;
import com.google.errorprone.refaster.annotation.AfterTemplate;
import com.google.errorprone.refaster.annotation.BeforeTemplate;
Expand Down Expand Up @@ -45,4 +47,20 @@ Optional<JsonNode> after(JsonNode node, String fieldName) {
return node.optional(fieldName);
}
}

/**
* Prefer {@link ObjectMapper#valueToTree(Object)} over more contrived and less efficient
* alternatives.
*/
static final class ObjectMapperValueToTree {
@BeforeTemplate
JsonNode before(ObjectMapper objectMapper, Object object) throws JsonProcessingException {
return objectMapper.readTree(objectMapper.writeValueAsString(object));
}

@AfterTemplate
JsonNode after(ObjectMapper objectMapper, Object object) {
return objectMapper.valueToTree(object);
}
}
}
6 changes: 6 additions & 0 deletions ...ontrib/src/test/resources/tech/picnic/errorprone/refasterrules/JacksonRulesTestInput.java
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Original file line number Diff line number Diff line change
@@ -1,6 +1,8 @@
package tech.picnic.errorprone.refasterrules;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.NullNode;
import com.google.common.collect.ImmutableSet;
import java.util.Optional;
Expand All @@ -22,4 +24,8 @@ ImmutableSet<Optional<JsonNode>> testJsonNodeOptionalString() {
Optional.of(NullNode.getInstance().get("baz")),
Optional.ofNullable(NullNode.getInstance().get("qux")));
}

JsonNode testObjectMapperValueToTree() throws JsonProcessingException {
return new ObjectMapper().readTree(new ObjectMapper().writeValueAsString("foo"));
}
}
6 changes: 6 additions & 0 deletions ...ntrib/src/test/resources/tech/picnic/errorprone/refasterrules/JacksonRulesTestOutput.java
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Original file line number Diff line number Diff line change
@@ -1,6 +1,8 @@
package tech.picnic.errorprone.refasterrules;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.NullNode;
import com.google.common.collect.ImmutableSet;
import java.util.Optional;
Expand All @@ -22,4 +24,8 @@ ImmutableSet<Optional<JsonNode>> testJsonNodeOptionalString() {
NullNode.getInstance().optional("baz"),
NullNode.getInstance().optional("qux"));
}

JsonNode testObjectMapperValueToTree() throws JsonProcessingException {
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@mohamedsamehsalah mohamedsamehsalah Oct 30, 2025

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Not sure how we usually do this, but I am keeping this throws statement for the diff; ObjectMapper#valueToTree does not throw this exception.

return new ObjectMapper().valueToTree("foo");
}
}