DBT macro receives variable as string when dictionary is passed - dbt

Question

I'm new to DBT world and facing a strange issue.
Database - Snowflake.
Attached two test models , one test csv data file and one test macro file.
seed data file : sample_data.csv
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subdimension,datasource,datasource_label,scoring_metric,weight
facebook_impressions,pathmatics_facebook,Pathmatics Facebook,total_year_impressions,5
facebook_engagement,facebook,Facebook,total_year_interactions,2.5
facebook_engagement,facebook,Facebook,interactions_per_post,2.5
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I'm reading data from the seed csv file using call statement and creating a dictionary using fromjson(query_result).
if you look at TEST1 model , this reading data as dictionary is coded there . This dictionary is then passed to the macro scoring and the macro receives it as a dictionary as it should.
Now take a look at TEST2 model. It's the same thing but the only difference is , the reading data as a dictionary format is done through a macro called get_scoring_metrics .
Here TEST2 receives the dictionary from get_scoring_metrics and pass it on to the macro scoring. But this time the macro scoring receives data as a string instead of a dictionary and throws the exception str object has no attribute items. If you compile the models , you will see it.
How is this possible? Both cases I'm using the same code.
I need data in dictionary format for ease of developing a complicated model .
Any solution will be appreciated . Thank you.
MODEL TEST1 (WORKS CORRECTLY)
-- depends_on: {{ ref('sample_data') }}
{%- set datasource = 'facebook' -%}
-- DICTIONARY THAT MAPS METRICS TO THEIR SUB-DIMENSIONS
{%- call statement('scoring_metric_query', fetch_result=True) -%}
SELECT TO_JSON(PARSE_JSON('{'||LISTAGG(diq_subdim,',')||'}')) AS diq_metric
FROM
(
SELECT subdim_name||':'||'['||scoring_metric||']' AS diq_subdim
FROM
(
SELECT '"'||subdimension ||'"' AS subdim_name,
LISTAGG(''''||scoring_metric ||'''' , ',') AS scoring_metric
FROM {{ ref('sample_data') }}
WHERE lower(datasource) = lower('{{ datasource }}')
GROUP BY subdimension
) T1
) T2
{%- endcall -%}
{% if execute %}
{%- set query_result = load_result('scoring_metric_query')['data'][0][0] -%}
{% set metric_dict = fromjson(query_result) %}
{% endif %}
{{
scoring(
datasource = datasource,
metric_dict = metric_dict
)
}}
MODEL TEST2 (Which throws exception during compilation even though I'm using same code as model TEST1)
{%- set datasource = 'facebook' -%}
{%- set metric_dict = get_scoring_metrics(datasource) -%}
{{
scoring(
datasource = datasource,
metric_dict = metric_dict
)
}}
macro scoring
{% macro scoring(datasource, metric_dict={} ) %}
--the query below means nothing. It's just an example to show that when this macro is called from test2.sql model, the metric_dict does not
--work as a dictionary but this macro receives metric_dict as a string (error- str objet has no attribute items).
--But when it's called from test1.sql model it receives metric_dict as a python dictionary.
{% for i , j in metric_dict.items() %}
select {{ i }} , {{ j }}
{% endfor %}
{% endmacro %}
macro get_scoring_metrics
{% macro get_scoring_metrics(datasource) %}
-- DICTIONARY THAT MAPS METRICS TO THEIR SUB-DIMENSIONS
{%- call statement('scoring_metric_query', fetch_result=True) -%}
SELECT TO_JSON(PARSE_JSON('{'||LISTAGG(diq_subdim,',')||'}')) AS diq_metric
FROM
(
SELECT subdim_name||':'||'['||scoring_metric||']' AS diq_subdim
FROM
(
SELECT '"'||subdimension ||'"' AS subdim_name,
LISTAGG(''''||scoring_metric ||'''' , ',') AS scoring_metric
FROM {{ ref('sample_data') }}
WHERE lower(datasource) = lower('{{ datasource }}')
GROUP BY subdimension
) T1
) T2
{%- endcall -%}
{% if execute %}
{%- set query_result = load_result('scoring_metric_query')['data'][0][0] -%}
{% set metric_dict = fromjson(query_result) %}
{{ return(metric_dict) }}
{% endif %}
{% endmacro %}
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