Java Projection.isFieldRequiredToEvaluateProjection方法代码示例

import com.redhat.lightblue.query.Projection; //导入方法依赖的package包/类
/**
 * Returns a list of the field names that are needed for the operation to be
 * successful.
 * @param md - {@link EntityMetadata}.
 * @param projection - (optional) {@link Projection}.
 * @param query - (optional) {@link QueryExpression}.
 * @param sort - (optional) {@link Sort}.
 * @return list of field names.
 */
private Set<Path> gatherRequiredFields(EntityMetadata md,
        Projection projection, QueryExpression query, Sort sort) {
    Set<Path> paths = new HashSet<>();

    FieldCursor cursor = md.getFieldCursor();
    while (cursor.next()) {
        Path node = cursor.getCurrentPath();
        String fieldName = node.getLast();

        if (((projection != null) && projection.isFieldRequiredToEvaluateProjection(node))
                || ((query != null) && query.isRequired(node))
                || ((sort != null) && sort.isRequired(node))) {
            if (PredefinedFields.isFieldAnArrayCount(fieldName, md.getFields())) {
                /*
                 * Handles the case of an array count field, which will not actually exist in
                 * the ldap entity.
                 */
                paths.add(node.mutableCopy().setLast(PredefinedFields.createArrayFieldNameFromCountField(fieldName)).immutableCopy());
            }
            else {
                paths.add(node);
            }
        }
    }

    return paths;
}
 

import com.redhat.lightblue.query.Projection; //导入方法依赖的package包/类
/**
 * Returns all the fields required to evaluate the given projection, query,
 * and sort
 *
 * @param md Entity metadata
 * @param p Projection
 * @param q Query
 * @param s Sort
 *
 * All arguments are optional. The returned set contains the fields required
 * to evaluate all the non-null expressions
 */
public static Set<Path> getRequiredFields(EntityMetadata md,
                                          Projection p,
                                          QueryExpression q,
                                          Sort s) {
    Set<Path> fields = new HashSet<>();
    FieldCursor cursor = md.getFieldCursor();
    // skipPrefix will be set to the root of a subtree that needs to be skipped.
    // If it is non-null, all fields with a prefix 'skipPrefix' will be skipped.
    Path skipPrefix = null;
    if (cursor.next()) {
        boolean done = false;
        do {
            Path field = cursor.getCurrentPath();
            if (skipPrefix != null) {
                if (!field.matchingDescendant(skipPrefix)) {
                    skipPrefix = null;
                }
            }
            if (skipPrefix == null) {
                FieldTreeNode node = cursor.getCurrentNode();
                LOGGER.debug("Checking if {} is included ({})", field, node);
                if (node instanceof ResolvedReferenceField
                        || node instanceof ReferenceField) {
                    skipPrefix = field;
                } else {
                    if ((node instanceof ObjectField)
                            || (node instanceof ArrayField && ((ArrayField) node).getElement() instanceof ObjectArrayElement)
                            || (node instanceof ArrayElement)) {
                        // include its member fields
                    } else if ((p != null && p.isFieldRequiredToEvaluateProjection(field))
                            || (q != null && q.isRequired(field))
                            || (s != null && s.isRequired(field))) {
                        LOGGER.debug("{}: required", field);
                        fields.add(field);
                    } else {
                        LOGGER.debug("{}: not required", field);
                    }
                    done = !cursor.next();
                }
            } else {
                done = !cursor.next();
            }
        } while (!done);
    }
    return fields;
}
 

import com.redhat.lightblue.query.Projection; //导入方法依赖的package包/类
/**
 * Returns the fields included based on the requested projection and
 * reference field projection
 */
public static Set<Path> getIncludedFieldsOfEntityForProjection(ExecutionBlock block,
                                                               CompositeMetadata root,
                                                               Projection requestProjection) {
    Set<Path> fields = new HashSet<>();
    // What is the path prefix for this entity?
    CompositeMetadata md = block.getMetadata();
    Path entityPath = md.getEntityPath();
    Path globalPrefix = entityPath.isEmpty() ? Path.EMPTY : new Path(entityPath, Path.ANYPATH);
    // entityPath is either empty, meaning this is the root, or a path to a reference field
    // If entityPath is not empty, then find the projection in the reference field
    ResolvedReferenceField reference = block.getReference();
    Projection localProjection;
    if (reference != null) {
        localProjection = reference.getReferenceField().getProjection();
    } else {
        localProjection = null;
    }
    FieldCursor cursor = md.getFieldCursor();
    Path skipPrefix = null;
    Path globalField;
    while (cursor.next()) {
        Path localField = cursor.getCurrentPath();
        globalField = globalPrefix.isEmpty() ? localField : new Path(globalPrefix, localField);
        FieldTreeNode node = cursor.getCurrentNode();
        if (skipPrefix != null) {
            if (!localField.matchingDescendant(skipPrefix)) {
                skipPrefix = null;
            }
        }
        if (skipPrefix == null) {
            if (node instanceof ResolvedReferenceField
                    || node instanceof ReferenceField) {
                skipPrefix = localField;
            } else if ((node instanceof ObjectField)
                    || (node instanceof ArrayField && ((ArrayField) node).getElement() instanceof ObjectArrayElement)
                    || (node instanceof ArrayElement)) {
                // include its member fields
            } else if(node instanceof ArrayField && ((ArrayField) node).getElement() instanceof SimpleArrayElement) {
                fields.add(new Path(localField,Path.ANYPATH));
            } else {
                if (localProjection != null && localProjection.isFieldRequiredToEvaluateProjection(localField)) {
                    LOGGER.debug("{}: required", localField);
                    fields.add(localField);
                }
                if (requestProjection != null && requestProjection.isFieldRequiredToEvaluateProjection(globalField)) {
                    LOGGER.debug("{}: required", localField);
                    fields.add(localField);
                }
            }
        }
    }
    return fields;
}