Example Of How To Create Joined View Use The API For Python
Introduction
Hosted joined views are a powerful feature in ArcGIS that allow you to combine data from multiple sources into a single view. This can be particularly useful for creating complex analyses or visualizations that require data from multiple tables or feature layers. In this article, we will explore how to create hosted joined views using the ArcGIS API for Python.
Understanding the ArcGIS API for Python
Before we dive into the code, it's essential to understand the ArcGIS API for Python and its various components. The API provides a set of classes and methods that allow you to interact with ArcGIS services, including feature layers, tables, and views. In this example, we will be using the ViewManager
class to create a hosted joined view.
Creating a Hosted Joined View
To create a hosted joined view, you will need to have a feature layer and a related table. The feature layer should have a relationship with the related table, which can be established by creating a relationship class in the feature layer's properties.
Here is an example of how to create a hosted joined view using the ViewManager
class:
from arcgis.gis import GIS
from arcgis.features import FeatureLayer, FeatureLayerCollection, Table
from arcgis.gis._impl._dataclasses._viewdc import JoinType
# Initialize the GIS object
gis = GIS("https://www.arcgis.com", "username", "password")
# Search for the feature layer and related table
flc_item = gis.content.search(rf"id:<hfl_itemid>", item_type="Feature Service")[0]
flc = FeatureLayerCollection(flc_item.url)
tbl = Table(flc_item.url + r"/" + str(rel['relatedTableId']))
# Create a hosted joined view
view_item = flc.view_manager.create_join_layer(
join_name=rf"{rel['name']} test joined view",
target_join_fields=["FeatureGUID"],
join=tbl,
join_fields=["GlobalID"],
join_type=JoinType.INNER,
include_geometry=True,
owner=gis.users.me
)
print(rf"Created joined view for relationship: {rel['name']}")
Using Private Classes to Access the _JoinType Enumeration
As you may have noticed, the JoinType
enumeration is a private class that is not directly accessible. To access this enumeration, you will need to use the arcgis.gis._impl._dataclasses._viewdc
module, which contains the private classes.
Here is an example of how to use the private classes to access the JoinType
enumeration:
from arcgis.gis._impl._dataclasses._viewdc import JoinType
Common Errors and Solutions
When creating hosted joined views, you may encounter various errors. Here are some common errors and their solutions:
- Error:
AttributeError: 'FeatureLayerCollection' object has no attribute 'view_manager'
- Solution: Make sure that you have initialized the
FeatureLayerCollection
object correctly and that it has aview_manager
attribute. - Error:
AttributeError: 'Table' object has no attribute 'relatedTableId'
- Solution: Make sure that you have initialized the
Table
object correctly and that it has arelatedTableId
attribute. - Error:
TypeError: 'str' object is not callable
- Solution: Make sure that you have not assigned a string value to a variable that is meant to be a function.
Conclusion
Creating hosted joined views using the ArcGIS API for Python can be a powerful way to combine data from multiple sources into a single view. By understanding the ArcGIS API for Python and its various components, you can create complex analyses or visualizations that require data from multiple tables or feature layers. In this article, we have explored how to create hosted joined views using the ViewManager
class and how to use private classes to access the JoinType
enumeration. We have also discussed common errors and their solutions to help you troubleshoot any issues that you may encounter.
Example Use Case
Here is an example use case for creating a hosted joined view:
# Initialize the GIS object
gis = GIS("https://www.arcgis.com", "username", "password")
# Search for the feature layer and related table
flc_item = gis.content.search(rf"id:<hfl_itemid>", item_type="Feature Service")[0]
flc = FeatureLayerCollection(flc_item.url)
tbl = Table(flc_item.url + r"/" + str(rel['relatedTableId']))
# Create a hosted joined view
view_item = flc.view_manager.create_join_layer(
join_name=rf"{rel['name']} test joined view",
target_join_fields=["FeatureGUID"],
join=tbl,
join_fields=["GlobalID"],
join_type=JoinType.INNER,
include_geometry=True,
owner=gis.users.me
)
print(rf"Created joined view for relationship: {rel['name']}")
This example creates a hosted joined view between a feature layer and its related table. The ViewManager
class is used to create the joined view, and the JoinType
enumeration is used to specify the type of join to perform.
Best Practices
Here are some best practices to keep in mind when creating hosted joined views:
- Use the
ViewManager
class to create joined views: TheViewManager
class provides a convenient way to create joined views and manage their properties. - Use the
JoinType
enumeration to specify the type of join: TheJoinType
enumeration provides a set of predefined join types that can be used to specify the type of join to perform. - Include geometry in the joined view: Including geometry in the joined view can be useful for creating visualizations that require spatial data.
- Use the
owner
parameter to specify the owner of the joined view: Theowner
parameter can be used to specify the owner of the joined view, which can be useful for managing access to the view.
Q: What is a hosted joined view?
A: A hosted joined view is a type of view that combines data from multiple sources into a single view. It allows you to create complex analyses or visualizations that require data from multiple tables or feature layers.
Q: What is the ArcGIS API for Python?
A: The ArcGIS API for Python is a set of classes and methods that allow you to interact with ArcGIS services, including feature layers, tables, and views. It provides a convenient way to create and manage hosted joined views.
Q: How do I create a hosted joined view using the ArcGIS API for Python?
A: To create a hosted joined view, you will need to have a feature layer and a related table. The feature layer should have a relationship with the related table, which can be established by creating a relationship class in the feature layer's properties. You can then use the ViewManager
class to create the joined view.
Q: What is the ViewManager
class?
A: The ViewManager
class is a part of the ArcGIS API for Python that provides a convenient way to create and manage hosted joined views. It allows you to specify the type of join to perform, include geometry in the view, and specify the owner of the view.
Q: What is the JoinType
enumeration?
A: The JoinType
enumeration is a set of predefined join types that can be used to specify the type of join to perform. It includes types such as INNER, LEFT, RIGHT, and FULL OUTER.
Q: How do I specify the type of join to perform?
A: To specify the type of join to perform, you can use the JoinType
enumeration. For example, you can use JoinType.INNER
to perform an inner join.
Q: Can I include geometry in the joined view?
A: Yes, you can include geometry in the joined view by setting the include_geometry
parameter to True
.
Q: How do I specify the owner of the joined view?
A: To specify the owner of the joined view, you can use the owner
parameter. This can be useful for managing access to the view.
Q: What are some common errors and solutions when creating hosted joined views?
A: Some common errors and solutions when creating hosted joined views include:
AttributeError: 'FeatureLayerCollection' object has no attribute 'view_manager'
: Make sure that you have initialized theFeatureLayerCollection
object correctly and that it has aview_manager
attribute.AttributeError: 'Table' object has no attribute 'relatedTableId'
: Make sure that you have initialized theTable
object correctly and that it has arelatedTableId
attribute.TypeError: 'str' object is not callable
: Make sure that you have not assigned a string value to a variable that is meant to be a function.
Q: What are some best practices for creating hosted joined views?
A: Some best practices for creating hosted joined views include:
- Using the
ViewManager
class to create joined views - Using the
JoinType
enumeration to specify the type of join - Including geometry in the joined view
- Using the
owner
parameter to specify the owner of the view
By following these best practices and understanding the ArcGIS API for Python, you can create hosted joined views that are efficient, scalable, and easy to manage.